Hate to start another thread on this but I drove it home one night and the next morning it wouldn't start or bump start.

I heard some strange noises coming from the starter and I thought the timing chain may have skipped but I just confirmed it is timed correctly.

Spark is good on both sides.

Not sure if the valve clearances was ever done on this engine because I bought it used w/ ~14k miles on it.

Carbs haven't been *thoroughly* cleaned in a while but I would expect it to bump start at least but it won't.

Rate of fuel flow is fine.

Starter cranks fine.

Battery is charged.

Throttle cable is attached correctly.

Have you tried spraying starter fluid in the intake?

Hate to start another thread on this but I drove it home one night and the next morning it wouldn't start or bump start.

I heard some strange noises coming from the starter and I thought the timing chain may have skipped but I just confirmed it is timed correctly.

Spark is good on both sides.

Not sure if the valve clearances was ever done on this engine because I bought it used w/ ~14k miles on it.

Carbs haven't been *thoroughly* cleaned in a while but I would expect it to bump start at least but it won't.

Rate of fuel flow is fine.

Starter cranks fine.

Battery is charged.

Throttle cable is attached correctly.

Clean the carbs. I think thats the most common issue when the bike doesn't start. Other than that, bad fuel, but i don't really believe that it won't even stumble when you try to turn it on. Besides i assume it was running on the same tank last time it was running and you aren't nearly empty.

You checked everything else that would stop it from at least starting, so give those carbs a cleaning. When i clean them, i like to make sure that if i spray it into 1 hole in the carb, i can see it coming out of another.

I had an unknown issue recently where i checked everything at least 3 times and it still wouldn't start. Using starting fluid and a LOT of cranking (not all at once), i got her running again.

Have you tried spraying starter fluid in the intake?

Do you mean to check for leaks or to get it started?

To get it started. If it pops and turns over than your not getting gas so your carbs are bad or you dont have gas going to them.

Do you mean to check for leaks or to get it started?

If you spray starting fluid straight into the intake (not the air filter), and your engine starts, then that eliminates anything in your engine from being a problem.

If it doesn't start, then it is most likely in your engine.

Cleaning the carbs now.

Anyone know a good solution to getting my pilots out? Theyre stuck inside I've never been able to get both out

Cleaning the carbs now.

Anyone know a good solution to getting my pilots out? Theyre stuck inside I've never been able to get both out

I had the same issue, first time I didn't even clean them.

Second time i was determined.

I don't think mine were taken out since 1987 because they had corrosion on them...

I used a screwdriver i had for decades, before i was born probably, had to file down the sides, but finally got it.

If you live in USA you should have no problem, just take your carb into the store and look for a screw driver that will take out that pilot. Try not to use something with a small blade (for electronics) as you can strip the head of the pilot.

I had the same issue, first time I didn't even clean them.

Second time i was determined.

I don't think mine were taken out since 1987 because they had corrosion on them...

I used a screwdriver i had for decades, before i was born probably, had to file down the sides, but finally got it.

If you live in USA you should have no problem, just take your carb into the store and look for a screw driver that will take out that pilot. Try not to use something with a small blade (for electronics) as you can strip the head of the pilot.

Well I doubt I'd ever use these pilots since I have some one size up I'd been wanting to put in...

Well I doubt I'd ever use these pilots since I have some one size up I'd been wanting to put in...

If you are referring to stripping them then you are only winning half the battle. If you strip them inside and don't manage to take them out, you will have even more trouble extracting them.

Furthermore, I do not see a reason to change out the pilots, they are tuned pretty well. Why would you need more power idling?

If you are referring to stripping them then you are only winning half the battle. If you strip them inside and don't manage to take them out, you will have even more trouble extracting them.

Furthermore, I do not see a reason to change out the pilots, they are tuned pretty well. Why would you need more power idling?

I'm not running stock intake or exhaust. The jet kit provided me with one size of pilots I've never been able to try out.

During removal of the carbs I saw that a vacuum line on top of the carbs was disconnected. I'm not sure if it happened during removal or while driving. It was the bigger of the two that cross over cylinder 1's carb and criss cross..... My petcock is broken so it's passing fuel regardless of whether there is vacuum present or not.

Changed plugs and installed thoroughly cleaned carbs. Biked doesn't start.

Compression test reads less than 60 psi on both cylinders. Only thing I can think of is the valves being out of spec at this point. I bought this engine used at ~14k miles and who knows if the valves were ever done. I'm going to do them later today.

Any ideas other than valve clearances?

Changed plugs and installed thoroughly cleaned carbs. Biked doesn't start.

Compression test reads less than 60 psi on both cylinders. Only thing I can think of is the valves being out of spec at this point. I bought this engine used at ~14k miles and who knows if the valves were ever done. I'm going to do them later today.

Any ideas other than valve clearances?

Did you try spraying starting fluid into the intake? When I had trouble with my engine that eliminated a lot of variables from causing the problem.
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I don't know how much PSI these engines are suppose to run on, but so long as the 2 cylinders have similar values, you should be fine. You can check that the spark timing is good: put something like a long pencil down the plug hole and crank while watching spark plug for firing. When the pencil is somewhere around its peak of motion the spark should fire. Make sure you don't lose what you put down the plug hole and avoid metalic objects, they may scrape your piston head. other than that, I would put on an extenal battery, I had a car battery in my garage and use it to crank a bit faster. Go for a few cycles I went for 10 3 second cycles and eventually got her started. The reason this may be happening is that your fuel may not be flowing from the carbs to the engine, cranking gets everything flowing/moving.
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Tried to bump start it and also hooked it up to car battery and cranked it forever. Haven't tried any starter fluid I'd have to buy some.

What would cause bad spark timing?

The compression minimum I think is somewhere over 160 psi if I'm not mistaken. Last running engine I had read 180 psi on both sides. The thought just occurred to me that maybe my head gasket went.... Guess I should run a leakdown test as well.

You've confirmed the float bowls are full - right?

Just because the petcock is flowing fuel doesn't mean it's getting into the bowls.

Check all of the fuel filters throughout the system.

Confirm the gas is good.

Spraying starter fluid would tell you if it's a fuel issue (as noted by 1/4L).

Got the pilot jet out btw. I had to drill it out a little then get it with a screw extractor.

You've confirmed the float bowls are full - right?

Just because the petcock is flowing fuel doesn't mean it's getting into the bowls.

Check all of the fuel filters throughout the system.

Confirm the gas is good.

Spraying starter fluid would tell you if it's a fuel issue (as noted by 1/4L).

Yeah when I checked for fuel flow I confirmed fuel in the bowls.

Make sure you don't crank for too long at a time, the starter has a lot of current running through it, you can blow your starter. There is a key that locks the flywheel to the stator and if it shears, your spark will not fire at the right time, but this is highely unlikely as was explained to me by n4mwd and motodool. I would guess you have poor compression, but I wouldn't imagine that it won't even start.
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When you were checking timing, did you check that the rockers were in place? Also, why didn't you check clearances while you were in there?

Tighter clearances mean you will have high end power, larger clearances means you will have low end power at the trade off of high end. This means that with larger clearances, you will have an easier time starting the engine.

Valve clearances done, bike still doesn't start. Gonna get some rest and run the leak down test tomorrow. There is a possibility the battery is just low but I did try and bump start it so tomorrow I'll hook it up to a car battery first thing.

When you were checking timing, did you check that the rockers were in place? Also, why didn't you check clearances while you were in there?

I knew the valves were tight because I bought this engine used and who ever does valve clearances?? Decided to take a break and come back to it. I'm guessing it might be my head gasket or one or more of the valves.

I knew the valves were tight because I bought this engine used and who ever does valve clearances?? Decided to take a break and come back to it. I'm guessing it might be my head gasket or one or more of the valves.

You hit the nail on the head with the valve clearance job ;)

I can feel your frustration, i went through a similar process as you, hopefully yours is not serious. Try looking through my thread "Valve adjustment no good" maybe you will get some inspiration or idea of what you can check next.

BTW, i did have the valve cover off at one point when cranking, just to make sure everything was moving properly. It actually started with the cover off, which was quite amusing for a moment.

I got a short clip of my motor running with the valve cover off.anyhoo. If you have that low o compression your motor won't start. Ask me how I know lol

I got a short clip of my motor running with the valve cover off.anyhoo. If you have that low o compression your motor won't start. Ask me how I know lol

I'm taking a guess I warped my head gasket..... I'll know later I guess.

I'm taking a guess I warped my head gasket..... I'll know later I guess.

My case was due to worn rings.

My case was due to worn rings.

Did your bike die while you were riding it? My bike drove fine home but next day wouldn't start.....

Ran a leakdown test and it seems there are no leaks.

I dunno if this is an effective test but I also sprayed soapy water around the head gasket while pushing air in with a compressor and didn't observe any bubbles....

Looks like I may have to rebuild my spare engine real quick and swap the two while I figure out wtf is going on.......arghhh!!!

It's not the safety switch for the kickstand is it? Oh wow 14k on mileage yeah definitely check the valves.

It's not the safety switch for the kickstand is it?

O man I wish!! lol I'll double check just because you brought it up!

O man I wish!! lol I'll double check just because you brought it up!

You try bypassing the starter?

You try bypassing the starter?

Um, guess not? How do you do that?

I've tried bumpstarting it every time but from the sound of it the starter is fine.

Did your bike die while you were riding it? My bike drove fine home but next day wouldn't start.....

Ran a leakdown test and it seems there are no leaks.

I dunno if this is an effective test but I also sprayed soapy water around the head gasket while pushing air in with a compressor and didn't observe any bubbles....

Looks like I may have to rebuild my spare engine real quick and swap the two while I figure out wtf is going on.......arghhh!!!

It happened while i was out at the track. At the end of the day, my bike would not start. I killed the battery and after so many attempts at push started it fired up. Next day, it wouldn't start like previously. I checked compression and was getting numbers similar to yours.

I believe you jump the solenoid with a screwdriver but I would run it by one of the gear heads first or at least research it a bit. If the starter is cranking though it's probably something else.

well check your valves and adjust as needed. Tight valves can give you starting issues.

Already adjusted valves.

Is there any further troubleshooting I can do at this point with engine in place? I'm kind of lost as to where to go from here....

Smell the exhaust while you're cranking, air should come out and it should smell like fuel. Also pull a plug and test for spark, though I feel like you proabably tried that. 60psi sounds awfully low, do you have another gauge you can try or something else to test it on to verify its accuracy? For absolutely nothing happening it sounds like ignition and I think your compression tester is off, you should have SOMETHING with even the worst of vacuum leaks, gummed up carbs, etc. Especially since you just parked it.

Smell the exhaust while you're cranking, air should come out and it should smell like fuel. Also pull a plug and test for spark, though I feel like you proabably tried that. 60psi sounds awfully low, do you have another gauge you can try or something else to test it on to verify its accuracy? For absolutely nothing happening it sounds like ignition and I think your compression tester is off, you should have SOMETHING with even the worst of vacuum leaks, gummed up carbs, etc. Especially since you just parked it.

Wouldn't doubt it but this gauge has read very well in the past so I'm not too suspicious of it.

I guess I should test for spark timing at this point.......

I've also heard of connecting an air hose to your compression tester hose and listening for air hissing to find leaks, maybe regulate it to 60-90psi? At TDC I'd imagine as well

I've also heard of connecting an air hose to your compression tester hose and listening for air hissing to find leaks, maybe regulate it to 60-90psi? At TDC I'd imagine as well

Yeah I did that when I hooked it up to the leakdown tester and I sprayed soapy water all around..........Stumped!!!

Spray some Starter Fluid in the intake (after removing the air filter) or drip some gas directly into the carb throats (use a piece of clear tubing - put into gas and cover the end with your thumb) and see if it pops at all. If it does you have a fuel delivery problem.

If it doesn't, pull a plug or use a Spark Tester to confirm spark. Also confirm the plugs are correct.

Report back.

Spray some Starter Fluid in the intake (after removing the air filter) or drip some gas directly into the carb throats (use a piece of clear tubing - put into gas and cover the end with your thumb) and see if it pops at all. If it does you have a fuel delivery problem.

If it doesn't, pull a plug or use a Spark Tester to confirm spark. Also confirm the plugs are correct.

Report back.

I'm pretty sure there's no fuel delivery problem. I checked the rate of flow prior to disassembling carbs and cleaning them.

Grounded the plugs against the engine.

I'm pretty sure there's no fuel delivery problem. I checked the rate of flow prior to disassembling carbs and cleaning them.

Grounded the plugs against the engine.

Well at this point, you pretty much exhausted your options. I think you should pull off the carbs and spray some starting fluid directly into the intake of the engine. If it doesn't start then there is definitely something wrong with the engine. This is just a sanity check and is an easy way for you to forget about the carbs and concentrate on the engine.

When you checked for timing, did you make sure that you got cylinder 2 TDC with EX and IN level with the head? I thought that i got it at one point, but was wrong because my crank moved, and although the EX and IN were aligned, the 2T was not.

Furthermore, did you check to see WHEN the spark fires?

Ok here's what I would do to check it ... Scrap everything that has been previously done... And don't assume anything ... This is a sure fire way to eliminate any questions about fuel or spark.. It also doesn't hurt to pull gas tank and assure the coils are both hooked up correctly... There is a correct wire polarity on them make sure it's is right
1.. Go buy at least 2 new spark plugs and a can of starting fluid...
2.. Pull air cleaner off and ensure battery charged or run jumpers to car battery
3.. Replace spark plugs with new ones>>> why u ask because in my past experience I've had plugs I knew were fouled fire like normal outside of engine... But fail when under compression
4.. Crack open throttle and spray a fair amount of steerer fluid in each carb throat and crank it over .. Repeat several times to ensure you get enough fuel.. Listen for it to pop or try to start ...
5.. If no fire or start pull plugs and see if there wet if so I would look into possibly something else with engine....
6.. It also never hurts to check battery to motor or chassis ground and also make sure your harness has a good chassis ground as well

I'm pretty sure there's no fuel delivery problem. I checked the rate of flow prior to disassembling carbs and cleaning them.

Grounded the plugs against the engine.
At this point I wouldn't assume anything.

Start over - and confirm everything.

Do as Rollingmenace and I suggested before tearing everything apart.

I'd also get some fresh gas to use for testing before much else.

Judging by the way you described the onset of the issue, I'm not convinced it's a major engine problem at this point.

Well at this point, you pretty much exhausted your options. I think you should pull off the carbs and spray some starting fluid directly into the intake of the engine. If it doesn't start then there is definitely something wrong with the engine. This is just a sanity check and is an easy way for you to forget about the carbs and concentrate on the engine.

When you checked for timing, did you make sure that you got cylinder 2 TDC with EX and IN level with the head? I thought that i got it at one point, but was wrong because my crank moved, and although the EX and IN were aligned, the 2T was not.

Furthermore, did you check to see WHEN the spark fires?

I haven't checked to see when the spark fires that's what I need to do soon.

Yeah I did confirm ex and in were level with head and at 2dc with 33 links in between. Dunno wtf is going on.....

Ok here's what I would do to check it ... Scrap everything that has been previously done... And don't assume anything ... This is a sure fire way to eliminate any questions about fuel or spark.. It also doesn't hurt to pull gas tank and assure the coils are both hooked up correctly... There is a correct wire polarity on them make sure it's is right
1.. Go buy at least 2 new spark plugs and a can of starting fluid...
2.. Pull air cleaner off and ensure battery charged or run jumpers to car battery
3.. Replace spark plugs with new ones>>> why u ask because in my past experience I've had plugs I knew were fouled fire like normal outside of engine... But fail when under compression
4.. Crack open throttle and spray a fair amount of steerer fluid in each carb throat and crank it over .. Repeat several times to ensure you get enough fuel.. Listen for it to pop or try to start ...
5.. If no fire or start pull plugs and see if there wet if so I would look into possibly something else with engine....
6.. It also never hurts to check battery to motor or chassis ground and also make sure your harness has a good chassis ground as well

I'll buy some new plugs that's not a bad idea.

For future reference you can clean fouled plugs. If you have been cranking for a long time, pull out your plugs and check their condition/colour. Do a quick google search on plug conditions and use it to compare.
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I'll buy some new plugs that's not a bad idea.

I've been riding and working on bikes for a long time I've brought many back from the dead lol... If you follow the steps as I laid out for you it should give you a really good indication of problems with the fuel or spark... And I believe your problem is most likely real simple

I've been riding and working on bikes for a long time I've brought many back from the dead lol... If you follow the steps as I laid out for you it should give you a really good indication of problems with the fuel or spark... And I believe your problem is most likely real simple

As sad it is to say, i believe he has low compression, for what ever reason...

Which bring me to another concern, it is weird that both cylinders lost compression... Did both cylinders loose compression simultaneously, or was one low on compression and the other was doing all the work? Did the bike ride different from your other engines?

This could mean that your cylinders are leaking compression between each other. Diagnosing it with soap won't identify it since its not an external area. This would mean a new head gasket.

As sad it is to say, i believe he has low compression, for what ever reason...

Which bring me to another concern, it is weird that both cylinders lost compression... Did both cylinders loose compression simultaneously, or was one low on compression and the other was doing all the work? Did the bike ride different from your other engines?

This could mean that your cylinders are leaking compression between each other. Diagnosing it with soap won't identify it since its not an external area. This would mean a new head gasket.

This is why I suggested the compressed air, it should blow out either the intake or the exhaust of the other cylinder, pcv, head gasket. If there's a leak it has to go somewhere


and you're absolutely sure valve timing is correct? Where are the timing marks? can they move relative to the crank? Sheared key? It seems like the pistons are lagging behind, or you didn't find a leak between the two

This is why I suggested the compressed air, it should blow out either the intake or the exhaust of the other cylinder, pcv, head gasket. If there's a leak it has to go somewhere


and you're absolutely sure valve timing is correct? Where are the timing marks? can they move relative to the crank? Sheared key? It seems like the pistons are lagging behind, or you didn't find a leak between the two

I'm not 100% anymore on the timing so I'll re check it. I bought some starter fluid so I'll try that as well but it seems pointless with low compression.

Once again I'm ready to launch this bike off the pier.

This is why I suggested the compressed air, it should blow out either the intake or the exhaust of the other cylinder, pcv, head gasket. If there's a leak it has to go somewhere


and you're absolutely sure valve timing is correct? Where are the timing marks? can they move relative to the crank? Sheared key? It seems like the pistons are lagging behind, or you didn't find a leak between the two

Is the sheared key in between the alternator and the starter gear somewhere? I can hear the engine cranking like normal it's just not starting.

Is the sheared key in between the alternator and the starter gear somewhere? I can hear the engine cranking like normal it's just not starting.

You have to pull of the stator cover to check.

If you were planning to check timing again, and you confirm that the cams and crank are at the right spot, then you don't have to worry about that key.

Timing is fine.

I've decided I'm going to pull this engine and check the condition of the rings. I know I don't have to pull the engine but it's a lot easier for me that way. In the meantime I think I'm gonna go full speed at assembling this spare engine I already have in my bedroom.

Actually did you check compression again after you adjusted the valves? That could have been another issue not related to the no start. Also if you had bad rings you would hear compressed air blowing out the PCV with my air test

Actually did you check compression again after you adjusted the valves? That could have been another issue not related to the no start. Also if you had bad rings you would hear compressed air blowing out the PCV with my air test

I did not recheck compression right now one of the fittings is stuck inside the spark plug threads from the leak down tester. It usually does get stuck but I've always managed to get it out before.....

I did try to jumpstart and bumpstart it to no avail.

I'll hook up the compressor to it again and listen better. I may have rushed a little. It's just a pain when my compressor kicks on every 5 seconds but I'll relocate it this time.

If you hear no air escape and still have low compression I'd wonder about the seal between the cylinders

Don't do it solely for the Rings though, a leak down will be more accurate. The air is just to give you an idea of where that compression is going off to

would you hear air flowing out the crank vent? the piston definitely gets up above 10:1 from room air pressure, but thats such a tiny volume compared to the total volume in the crank case... the amount of blow by even if it was completely shot rings would be pretty minor... would you even notice it? maybe if you plugged the crank vent with your finger you could feel the additional pressure on it...

would you hear air flowing out the crank vent? the piston definitely gets up above 10:1 from room air pressure, but thats such a tiny volume compared to the total volume in the crank case... the amount of blow by even if it was completely shot rings would be pretty minor... would you even notice it? maybe if you plugged the crank vent with your finger you could feel the additional pressure on it...

I was thinking the breather body would conflict with the flow of air.....

The leak down tester is a little ambiguous because if you increase the psi enough it will test good it seems.....

Stumped... I'll check the warp of the head when I pull the #$%^^

I was thinking the breather body would conflict with the flow of air.....

The leak down tester is a little ambiguous because if you increase the psi enough it will test good it seems.....

Stumped... I'll check the warp of the head when I pull the #$%^^

Hi Justin,

I would fine check the electrical part before you take the engine out and apart.

Rings and valves don't go bad from Sunday to Monday.
One cylinder may have a valve stuck half way open, but not both cylinders at once.
Heads don't warp up without over-heating.

When verifying compression, determining poor sealing of valves against rings is just a tea spoon of oil away.

Do you remember what happened to the bike just before last Sunday?
Refill, fall over, maintenance, rained over, over-heat, etc.?

Check the intensity of the sparks by removing the plugs and inserting a screwdriver into the cable and making a gap of 1/4" from any ground body.
If the there is no spark jumping that big gap, there will not be spark jumping in the plugs at more than 100 psi (even when they happily jump the gap of the electrodes at atmospheric pressure).

Maybe some marginal electrical connection has reached the point of dropping the secondary voltage below the critical point (no sparks at high P).
Same if the voltage in the battery goes below 10.5 or 10 volts during cranking the starter.

It seems to me that tearing this engine apart for visual inspection will not tell you much.

Hi Justin,

Check the intensity of the sparks by removing the plugs and inserting a screwdriver into the cable and making a gap of 1/4" from any ground body.

Maybe some marginal electrical connection has reached the point of dropping the secondary voltage below the critical point (no sparks at high P).
Same if the voltage in the battery goes below 10.5 or 10 volts during cranking the starter.

It seems to me that tearing this engine apart for visual inspection will not tell you much.

Are you saying to insert a screwdriver head first into the cable and observe an arc from the shaft of it?

I didn't know spark could be inhibited by high pressures. Learned something new today.

Hi Justin,

When verifying compression, determining poor sealing of valves against rings is just a tea spoon of oil away.

I did forget to put oil in the cylinders.... There has been no smoke out of the exhaust.

Do you remember what happened to the bike just before last Sunday?
Refill, fall over, maintenance, rained over, over-heat, etc.?

Fall over and over heat are two definite possibilities. I don't have confidence in my thermo switch but I do run a second switch straight to the radiator fan....

It seems to me that tearing this engine apart for visual inspection will not tell you much.

At least I can eliminate any engine issues (in theory) when I put my spare engine in. If it starts then that should tell me something. If not then there is still much left to question.

Are you saying to insert a screwdriver head first into the cable and observe an arc from the shaft of it?

I didn't know spark could be inhibited by high pressures. Learned something new today.

Yes, but keep your fingers from becoming a conductor themselves.

http://www.kesteleyn.net/500/figures/fig%201.20.gif

It is called Paschen's Law: "For a given gas, the voltage is a function only of the product of the pressure and gap length."

http://en.wikipedia.org/wiki/Paschen%27s_law

Copied from:
http://www.dansmc.com/electricaltesting.htm

"When you check for spark, the spark must jump at least 1/4" (.250") or more outside the engine. Just laying the spark plug in the plug cap, on the cylinder head, and getting a spark across a .030" gap is no good. It takes a lot more power to jump a gap under compression in the engine then outside the engine under no compression pressure. Also, if it's electronic ignition, you must spin the engine to at least three or four hundred RPM. Any less and the anti kick back circuitry in the CDI black box kills the spark."

+1 on the gap test/low-voltage. But if you had a problem with a switch you wouldn't have spark at all

My guess is once again that you are not getting fuel or getting too much of it. Are the plugs wet after you crank the engine and attempt to start it? TRY SOME STARTER FLUID TO ISOLATE THE PROBLEM.

+1 on the gap test/low-voltage. But if you had a problem with a switch you wouldn't have spark at all

What switch?

Oh you mean the interlocks? Kickstand switch is fine and I tried starting the bike in neutral so the clutch switch would be irrelevant.

Yeah I'm saying if you had any electrical issues apart from weak spark you wouldn't have spark at all. Also spark shouldn't just go weak overnight, you'd notice it running worse and worse, particularly at high rpm where you have less dwell time. I would expect misfires and severe lack of power leading up to this.

Did you try the starting fluid yet?

i did have loss of power the days leading up to this.

I havent touched my bike today I've been working on my spare.

Not sure why you think starting fluid is going to do anything. The minimum usable compression is 139 psi. Not one of my cylinders have half that...

You have a spark to ignite it

You have a spark to ignite it

Tomorrow, possibly Monday.

I'm not convinced you tested the compression correctly.

Did you test it with the throttle wide open?

I'm not convinced you tested the compression correctly.

What reason do you have to not be convinced? I've run this test many times before. The minimum useable psi is 139. There is something wrong.

What reason do you have to not be convinced? I've run this test many times before. The minimum useable psi is 139. There is something wrong.

What my concern, and I believe quarterliter meant this, is that your diagnostics have a loophole somewhere.

What I mean is that you say you have low compression, but nothing to back it up with, I.e. Leak down test shows nothing, no air leaking from compression, etc.
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Yes I think there was some diagnosis error. The ridiculously low reading backs up my theory

Well I haven't had time to run another leak down test. Remember I said the compressor kept kicking on which made it difficult to hear anything. All I really tested was the valve seating at TDC. I have a new (longer) air hose now so I can relocate my compressor and actually have a good listen. Most likely tomorrow or Wed.

Oh and that all depends if I can get that connector out of the spark plug threads. My usual methods have failed me so far.

I was not talking about a leakdown test but a compression test. What was you procedure for the compression test?

I was not talking about a leakdown test but a compression test. What was you procedure for the compression test?

The same procedure I've used in the past which had shown my compression was good when it was in fact good.

Not what I asked. I'm almost done trying to help you here.

Not what I asked. I'm almost done trying to help you here.

I didn't know you had started. :p

Go ahead swap in another engine. Be my guest just trying to help you. But you have yet to take mine or many others advice. Your reading of less than half the usable value leads me to believe you messed up your testing process. But you maintain that you are correct. At 14k the chances of the compression being that low is almost none.

Go ahead swap in another engine. Be my guest just trying to help you. But you have yet to take mine or many others advice. Your reading of less than half the usable value leads me to believe you messed up your testing process. But you maintain that you are correct. At 14k the chances of the compression being that low is almost none.

Not so. My last engine had spun bearings in the rods at ~19k miles and I have only driven harder since that. I'm just waiting til money comes in to get another bike. I push these engines to their max. Trust me.

You can't tell me a compression test is that difficult. WOT and crank it til the needle tops out. What's so hard about that?

You killed an engine in 19k? What do you do? Run crappy oil, beat it when its cold, or a combination of the two?

Justin, have you done a wet compression test? Put some oil into the spark plug hole and test compression again. It jumps up significantly you have worn rings like I did.

Justin, have you done a wet compression test? Put some oil into the spark plug hole and test compression again. It jumps up significantly you have worn rings like I did.

I can't do any testing right now the connector for the leak down tester is stuck in the cylinder. I plan on putting the spare in though and doing some head maintenance so I can visually see what is going on at that time.

You killed an engine in 19k? What do you do? Run crappy oil, beat it when its cold, or a combination of the two?

I've always ran Mobil1 full synthetic motorcycle oil so you tell me if it's crappy. I've never beat an engine cold but I guess I'm not an expert like you so maybe I've been doing something wrong.

I ride it on one wheel a majority of the time I imagine that has something to do with it.

You are a victim of oil starvation then. Didn't realize you were a "stunter." What made you choose a 250 as your stunt bike?

You are a victim of oil starvation then. Didn't realize you were a "stunter." What made you choose a 250 as your stunt bike?

Didn't know I was so into it when I bought the 250, been too poor to buy anything else. I'll have a 600 in a couple months though so I can be easy on the ninja.

90s 600s can be had cheap around where I live. Might not be a bad choice. Maybe a Honda F2 or F3

I can't do any testing right now the connector for the leak down tester is stuck in the cylinder. I plan on putting the spare in though and doing some head maintenance so I can visually see what is going on at that time.

I have that issue from time to time. What you need to do I'd find a long flat screwdriver and turn it out. Or get some thread lock on and let it harden and remove.

90s 600s can be had cheap around where I live. Might not be a bad choice. Maybe a Honda F2 or F3

^^^That's actually the route I'm going. I'm gonna be able to afford a used one in Dec.

I have that issue from time to time. What you need to do I'd find a long flat screwdriver and turn it out. Or get some thread lock on and let it harden and remove.

Worked like a charm why didn't I think of that?!?

OK, time to rip the head off this engine and see what's going on. I don't have money for new gaskets so it'll just be on hold for a little while after I pull it.

Pulled the head and block off the engine tonight and I see that cylinder one piston was scraping against the cylinder wall leaving marks on the sides of the piston. There was also rust on top of the cylinder. I'm going to be spending some time cleaning this engine up, lapping the valves, replacing the head gasket and putting new rings on and probably a new piston.

27271

Thoughts?

Both engines I have have had issues with clyinder one somewhere. Last engine had spun bearings in rod 1.

It makes sense since it's the last to get fed oil.

I wonder what these markings mean. My last engine didn't have any of these on the pistons....

Parts weren't lining up is my thought, also possibly insufficient lubrication. Could a warped head do that?

Oil starvation/possibly getting some contaminants in the engine from bad air filtration. Something fairly good size. Have you stunted on this specific engine?

Oil starvation/possibly getting some contaminants in the engine from bad air filtration. Something fairly good size. Have you stunted on this specific engine?

Yea. I wonder why compression was low still

A few points.

First off, you can't trust the reading from a Harbor Freight compression tester. Its more important that they are approximately equal.

Second, if the oil filter isn't installed correctly, it will not filter the oil. Contaminants get into the passages and destroy the bearings. Engines can be trashed because the order of parts isn't right and the oil gets through unfiltered.

Cleaned out the cylinders last night and aside from the rust it seems like they had some uneven wear? Especially cylinder one. Am I imagining things and is just some rust caked on or did they actually wear unevenly??

I'd rather not replace the rings if I could avoid it because of costs. It looks like I'll have to hone them a tad bit though.... The engine had about 14k miles on it is that normal.

Justin, you'll need to check for roundness of the bores before you do anything. Best bet is to take it to a machine shop so they can check it and to make sure your head and block is square.

You'll probably need a new set of rings if they damaged/scored.

Justin, you'll need to check for roundness of the bores before you do anything. Best bet is to take it to a machine shop so they can check it and to make sure your head and block is square.

You'll probably need a new set of rings if they damaged/scored.

I got a set of telescoping gauges coming in the mail today

Edit: Actually I just tracked it and it won't be here for a while. Wow harbor freight way to be the slowest online store.

Cut out a gasket for the clutch cover but oil still leaks. Im just going to go buy some gasket maker type stuff from the auto store I'm a little frustrated after cutting out a gasket from paper. Last owner had some grey gasket maker on there and it worked fine but I'll find something less elastic. Can't ride tonight because of this stupid issue.

Cut out a gasket for the clutch cover but oil still leaks. Im just going to go buy some gasket maker type stuff from the auto store I'm a little frustrated after cutting out a gasket from paper. Last owner had some grey gasket maker on there and it worked fine but I'll find something less elastic. Can't ride tonight because of this stupid issue.

What type of gasket paper did you use? Did you get staples or somebody to print it for you?

What type of gasket paper did you use? Did you get staples or somebody to print it for you?

Not exactly sure on the name but I think it was called "gasket paper." It was tan in color.

I traced it and the outline was good but the holes were a pain to cut out. Of course by the pressure relief valve the oil comes out of the cover so I'm just gonna do it the easy way and order gaskets from now on.

Not exactly sure on the name but I think it was called "gasket paper." It was tan in color.

I traced it and the outline was good but the holes were a pain to cut out. Of course by the pressure relief valve the oil comes out of the cover so I'm just gonna do it the easy way and order gaskets from now on.

If you used gasket paper then it should have worked fine if everything lined up. The factory ones are just paper themselves. Were the mating surfaces clean?

To cut the holes, just use a hole puncher.

so what happen? does it run yet?

so what happen? does it run yet?

It runs just had a oil leak from the right cover

It runs just had a oil leak from the right cover

how did you fix it?

There is no mystery about what killed the piston in the picture, or the rust in the cylinder. Oil starvation pure and simple. Oil starvation seized the skirt, lack of oil and overheating destroyed the oil film on the cylinder, and it rusted soon after. I hope your "next" bike has a dry sump oiling system or you will kill it too. Or better yet get a 2 stroke bike and run premix in it.

My creds? I have earned a living as a mechanic and engine builder for 42 years.

There is no mystery about what killed the piston in the picture, or the rust in the cylinder. Oil starvation pure and simple. Oil starvation seized the skirt, lack of oil and overheating destroyed the oil film on the cylinder, and it rusted soon after. I hope your "next" bike has a dry sump oiling system or you will kill it too. Or better yet get a 2 stroke bike and run premix in it.

My creds? I have earned a living as a mechanic and engine builder for 42 years.

Good to know. Can you explain to me what a dry sump system is and are they on a lot of sport bikes?

I'm not sure how the engine became oil starved as the volume was fine. I do believe it was in need of an oil change though. 6000 miles or 6 months as the owners manual states is a little far fetched.

A dry sump engine does not store the oil in the crankcase. As the oil circulates thru the engine and makes its way into the crankcase area, a "scavenge" pump sucks up the oil and returns it into a remote oil tank. The pressure pump sucks the oil from the tank and feeds the engine.

A dry sump system is less affected by stunts such as wheelies.

A 250 Ninja engine is a "wet sump" engine. All the oil lives in the bottom of the engine. If you do a wheelie, the oil goes to the back of the engine. when that happens, the oil pickup (the "screen") loses contact with the oil, and sucks air.

You can't lube a motor with air. Either quit the wheelies, or get a different bike that has a dry sump. A Buell air cooled bike would be a good choice since they have dry sump oiling. But remember if you do a wheelie long enough, ALL motors will starve for oil and fail.

Put new paper gasket on clutch cover. Filled oil. Bike starts up and runs like a champ.

Countdown to next rebuild.

Get a buell blast, they have a dry sump. Fast1057 is right here, its amazing that the ninja will run that long without oil pressure, but its only a matter of time till this happens again. Maybe more catastrophically next time.

Get a buell blast, they have a dry sump. Fast1057 is right here, its amazing that the ninja will run that long without oil pressure, but its only a matter of time till this happens again. Maybe more catastrophically next time.

Yeah lessoned learned here. Don't do wheelies on a 4 stroke 250cc with .01 Hp

Displacement and horsepower are not what caused this engine harm. Any wet sump engine would have experienced the same issue. But for real, a buel blast would be your best bet.

The Ninja 250 isn't going to oil starve during a wheelie because the oil pickup is at the rear of the engine. As long as its got the required 2 quarts in there, it should have no problem. The problem is the opposite - braking. Something like a stoppie is going to starve the engine for oil. Even heavy braking is bad.

Another thing that is VERY bad is after an accident and the bike is on its side, if the engine continues to run, its running without oil. Usually the carbs will flood and stall the engine, but not always.

The Ninja does have a problem with oil frothing at RPM's greater than 7K or so. What happens is that the oil gets splashed around so much that it becomes a bit frothy and then foams out of the oil breather. If its hooked to the airbox then it just gets sucked into the engine and burned. But if its just sitting there with a little pod, then it runs out on the street.

A dry sump system would probably fix that, but IMHO isn't not worth the extra weight on the Ninja. Just don't do stoppies or hard brake any more than absolutely necessary and keep an eye on the oil level.

Justin uses full synthetic oil which can tolerate a second or two of zero pressure without damage. I don't have an explanations for the pistons, but in this engine, the crank bearings are the first to go in a zero oil pressure situation. When the tolerance is measured in microns, it doesn't take much to mess it up.

Displacement and horsepower are not what caused this engine harm. Any wet sump engine would have experienced the same issue. But for real, a buel blast would be your best bet.

What I was getting at is the engine requires more revs for the same hp

I'm not convinced you are correct. That piston looked like it had experienced very high heat caused by oil starvation. I have heard of the oil light coming on during heavy breaking, but I think that the time spent doing a stoppie is relatively small compared to time doing a wheelie. Justin do you do stoppies for extended periods of time?

The oil pickup is in the rear of the engine so a wheelie would cause the pickup to be under more oil and not less.

Like I said, running on its side is the biggest threat - say after a failed wheelie.

Justin was experiencing high engine temps from an unknown cause prior to his rebuild. The engine also had a rolled bearing. I don't know if it was the same cylinder or not. Ironically, the high engine temps forced a rebuild before he damaged his crank. He was definitely quite lucky in that respect.

But because he uses full synthetic oil, I don't believe the problem was positional. I believe that something clogged up an oil passage and that was what did him in.

I have seen other bikes where the oil filter is installed incorrectly which crams debris at high pressure into the bearings and crank passages. I don't know if this was a factor with Justin's bike or not. It could have happened prior to him getting it even if he did everything correctly.

As far as I know, the piston and wrist pin are splash lubricated rather than pressure lubricated. The rods are solid and not hollow like some engines so there is no oil passing through them.

Could be foam related. The KZ-650/700/750 series would fail rod bearings if overfilled even slightly and run hard. I ran a windage tray and a sump baffle in my 810 turbo/nitrous drag bike successfully when others were killing cranks and rods.

Spinning a rod bearing in a stock motor is going to be a lube failure. There "should" be a spray notch in the rod to direct some oil towards the underside of the piston for cooling and lubrication.

Although it is a possibility the cylinder overheated causing it to seize. That will also destroy rod bearings. I built a 740 motor with MTC 13.5 forged pistons once that would tighten up and spin a bearing. Turned out the piston clearance needed to be quite a bit more than was specified. The pistons were "old school" forgings with very little silicon. They really expanded a lot with a 50 horse shot. Once I figured that out and set it up loose, it ran like a raped ape for two full seasons, but eventually broke a skirt from being loose.

I'm not convinced you are correct. That piston looked like it had experienced very high heat caused by oil starvation. I have heard of the oil light coming on during heavy breaking, but I think that the time spent doing a stoppie is relatively small compared to time doing a wheelie. Justin do you do stoppies for extended periods of time?

The brakes on this bike don't stoppie well, so no; not a chance.

In both my engines the issues are in cylinder one. Is it a coincidence that it is last in line to be fed oil in the camshafts? What happens when you overfill anyways?

The brakes on this bike don't stoppie well, so no; not a chance.

In both my engines the issues are in cylinder one. Is it a coincidence that it is last in line to be fed oil in the camshafts? What happens when you overfill anyways?
If the level is high enough the oil will become aerated (foamy/filled with air) and the engine will lose oil pressure.

If the level is high enough the oil will become aerated (foamy/filled with air) and the engine will lose oil pressure.

This is because the crank comes into contact with the oil.

This is because the crank comes into contact with the oil.

ahhh didnt know that