Bike won't start

[jkv45]

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.

[FvnnyL3tt3r1ng]

Originally Posted by jkv45

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.

[The_big_dill]

Originally Posted by FvnnyL3tt3r1ng

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?

[Rollingmenace]

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

[jkv45]

Originally Posted by FvnnyL3tt3r1ng

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.

[FvnnyL3tt3r1ng]

Originally Posted by The_big_dill

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.....

[FvnnyL3tt3r1ng]

Originally Posted by Rollingmenace

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.

[The_big_dill]

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.
Posted via Mobile Device

[Rollingmenace]

Originally Posted by FvnnyL3tt3r1ng

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

[The_big_dill]

Originally Posted by Rollingmenace

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.

[Felipe the Ant]

Originally Posted by The_big_dill

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

[FvnnyL3tt3r1ng]

Originally Posted by Felipe the Ant

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.

[FvnnyL3tt3r1ng]

Originally Posted by Felipe the Ant

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.

[The_big_dill]

Originally Posted by FvnnyL3tt3r1ng

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.

[FvnnyL3tt3r1ng]

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.

[Felipe the Ant]

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

[FvnnyL3tt3r1ng]

Originally Posted by Felipe the Ant

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.

[Felipe the Ant]

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

[Felipe the Ant]

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

[alex.s]

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...

[FvnnyL3tt3r1ng]

Originally Posted by alex.s

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 #$%^^

[Motofool]

Originally Posted by FvnnyL3tt3r1ng

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.

[FvnnyL3tt3r1ng]

Originally Posted by Motofool

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.

[FvnnyL3tt3r1ng]

Originally Posted by Motofool

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.

[Motofool]

Originally Posted by FvnnyL3tt3r1ng

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.



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."

[Felipe the Ant]

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

[quarterliter]

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.

[FvnnyL3tt3r1ng]

Originally Posted by Felipe the Ant

+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.

[Felipe the Ant]

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?

[FvnnyL3tt3r1ng]

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...

[Felipe the Ant]

You have a spark to ignite it

[FvnnyL3tt3r1ng]

Originally Posted by Felipe the Ant

You have a spark to ignite it

Tomorrow, possibly Monday.

[quarterliter]

I'm not convinced you tested the compression correctly.

[quarterliter]

Did you test it with the throttle wide open?

[FvnnyL3tt3r1ng]

Originally Posted by quarterliter

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.

[The_big_dill]

Originally Posted by FvnnyL3tt3r1ng

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.
Posted via Mobile Device

[quarterliter]

Yes I think there was some diagnosis error. The ridiculously low reading backs up my theory

[FvnnyL3tt3r1ng]

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.

[quarterliter]

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

[FvnnyL3tt3r1ng]

Originally Posted by quarterliter

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.