Im back with a ZZR 250 (Wont idle right and stall)

[juliusmichaelhonrada]

Its been 7 months , i sold my old 1987 GPX250-RII and bought a 2 stroke YAMAHA RX 135cc i love the power i feel like its more powerful than the gpx almost like 18 horses and very light.

Now i am back with a ZZR-250 my brother bought one cheap 25,000 pesos(around $500) , this time everything looks good i cant see any rust on the bike.

Things we had done:
1.Adjusted the timing(which is surprising because it was perfected by the P.O)
2 Adjusted the valve clearance(too tight 0.002 inch for the intake and 0.003 for the exhaust)
3.Replaced the floats (which is different) TOOK the floats from an old carb(EX250) and adjusted the height to 17mm.
4. Cleaned the Spark plugs (there was oil in the threads but not in the combustion chamber)


The bike starts off cold nice , it idles quite high around 2000 , then later it will drop to 1200-1400 , a 1 micron adjust of the idle adjuster and it will rise to 2000 , or sometimes when you blip the throttle , it will stay at 2000 then drop suddenly to 1200-1400 which you will need to catch or the engine will die.

When hot at around 3/4 temp gauge , the bike will run , but any input on the throttle has no effect on the engine rpm , it just stays at 1000-1200rpm so low that sometimes the oil light blinks and the scary sound of a LUGGING bike its like rattling the insides , if you let go of the throttle the engine dies, i tried using choke at full choke it will die but lesser than that uhm no effect.

My next test will be spraying gasoline directly in the mouth of the carburetor when it stalls at 3/4 temp range , that way i can isolate the problem or rule out the fuel delivery issues sadly it will be next week because im very busy now with school and work, im surprised that my old GPX250-RII will run better even though it looks junk, dies on 1 cylinder and had only 1 carburetor it still manage 120kph , this thing wont even run 50kph

Remember this?

Link to original page on YouTube.

Bike:



Theres my yamaha rx 135 , 2 stroke monster


Timing :





CARBURATION:






Spark plugs:
Left is cylinder #1 right is Cylinder #2



P.S
I also want to know why is there a coolant tube going to the float bowls , and why arent there any overflow pipe in the float bowl

[Motofool]

I believe that you should verify that there is a constant flow of fuel into the bowls when vacuum is applied to the petcock.
You don't mention whether you have cleaned all the passages of the carburetors.
There is no coolant hose going to the bowls.

[Mohawk]

As per above check fuel. The ZZR has a prime position on the fuel tap turn it half way so the vane is vertical. This let's fuel flow without a vacuum. Next check the carb diaphragms, if the throttle plate turns when you add throttle the vacuum should lift the slides. As you have pods it's easy to check if the slides are lifting.

If that's OK, then check the jets & air screw position.

Have fun.

[juliusmichaelhonrada]

Originally Posted by Motofool

I believe that you should verify that there is a constant flow of fuel into the bowls when vacuum is applied to the petcock.
You don't mention whether you have cleaned all the passages of the carburetors.
There is no coolant hose going to the bowls.

I will check it tomorrow morning , the carb is so clean its like new or something the only faulty part was the incompatible floats and it was corrected by replacing them from an old carb of an ex250.

There is coolant hoses going from the radiator tube that goes under the carb then goes directly to the coolant tube in the head




additional information:
The P.O said the issue of this bike was the connecting rod bearings that was causing all of this chaos , its hard to believe because the engine runs quietly not even a chain or a piston slap, seems like the P.O was getting ripped off by his mechanic

[Mohawk]

Those are the carb heater hoses, fitted to Euro & any "cool weather" climate sales versions they stop carb icing in cool damp or foggy conditions.

Having experienced carb icing on a Suzuki DRZ400 in cold fog, they are a good idea, if you live in a warm dry climate, you can try using a hose to linke the circuit bypassing the carbs with a straight piece of hose. The cooler the intake charge to a point the better !

Which one of those floats is the new one ? The one in the left of picture looks like mine, but mine are clear so you can tell if they leak !

[juliusmichaelhonrada]

The new float looks like this , it came from an ex250 carb, i didnt took a picture, i will do tomorrow we will tear up the carb again and clean the idle circuits , i will also get the bowls from the ex250 carb that has the overflow pipe and no coolant hoses mounting points.


Just 30 mins ago , we tested the ninja to the point of the redline on the temp gauge it refuses to start now, when i sprayed gas on it 2 sec later there is smoke coming out of the diaphragm slide ,i dont know if its vaporize fuel i touched the carb mouth and it wasnt hot, weird we didnt get the stalling "wont respond to throttle" this time , and the slides are good it comes up and comes down at the same time, the rpm's are slow to rise , like blip half throttle to idle and its only just 4k-5k rpm, it barely goes past 9k , cant even reach the 14k redline it seems impossible even at IDLE ,GEAR ON NEUTRAL AT WOT

I WILL TAKE A VIDEO

[juliusmichaelhonrada]

Cleaned the idle circuit , bike will start easily now , air screw 2.5 turns out.

EX250F VS ZZR250 CARBURETOR the dirty one is the ex250f , the clean one is the zzr250


*THE FLOATS ON THAT EX250F CAME FROM THE CARB OF THE ZZR250 WHEN WE BOUGHT THIS BIKE , CLEARLY ITS NOT STOCK*|

We just took the ex250f floats now its all stock with no modifications. I can say i had ruled out the carbs in the equation of why this bike wont run right eh?

I dont know what is wrong , theres fuel in the bowl , theres spark.

Video:

Bike starts easily , wont respond to throttle 1/8 , 1/4 1/2 , 3/4 OR WOT , NOTHING ! Let go of the throttle and it dies(ah now thats a response).

Link to original page on YouTube.

[Mohawk]

Are you sure the throttle cables are attached ? Are you sure the butterfly is opening when you twist the throttle ? One of two things should happen when you open the throttle. One the engine will Rev or at least attempt to, Two the engine will die. As neither is happening, that implies that the slides are NOT rising. Please check that the slides are fitted the correct way round, that means the hole in the bottom by the needle is towards the engine side they can be fitted back to front !

Next check the the slides do work, no tears in the diaphragms & no leaks around the carb tops. I use a hoover to prove this. Take the carbs off, use something to hold the butterfly in the open position. Then hold a running hoover or vacuum cleaner nozzle to the engine side of the carb, you should be able to watch the slides rise. Also ensure the needles are properly fitted to the slides.

[juliusmichaelhonrada]

IMPORTANT NOTE:
It doesnt happen all the time , at first it will rev and respond , later on it wont , ITS UNPREDICTABLE, BUT 1 THING HAS HAPPENED TO ME TWICE THAT MIGHT GIVE SOME CLUE when i was testing the bike zzr 250 have steering radius so small compared to small bikes , i have to stop then push the back bike a bit to do a complete U turn when exiting that u turn and i sometimes miss the clutch and engine will lug then this happens no throttle response even at WOT , let go and it dies, wait some time then the bike was fine again.

I am sure everything is in order , the slide works , the butterfly valve opens.

The diaphragm looks good except for 1 tear in the outer edge which i see has no way of affecting its operation and btw the slide cant be fitted the other way around theres only 1 way to fit it tested it and it comes up and comes down at the same time and when putting the cover on there is still rubber that seals it so theres no way it could leak there.

I have another spare diaphragm from the ex250f but the hole in the bottom slide is smaller,when we tested its operation the slide on the ex250f comes down slower than the zzr250, i am not certain about what will be the effects of putting the ex250f diaphragm on the zzr250 because theres nothing in the internet that shows that information.

Teared diaphragm:

Good diaphragm:





I have never seen anything like this in my life , this problem is so unusual theres not even anything about it in the internet

[Mohawk]

OK so the engine should die when you he throttle is opened & to much air gets in. That's not happening so the air flow is NOT increasing ! Can you confirm the carbs are able to supply fuel via the main jet ? Fill with fuel, then blow in the carb vent tube which is located between the carbs, fuel should pour out of the main jet !

[Mohawk]

I can't see the carb vent tube in your pictures !

[juliusmichaelhonrada]

yeah it does , bowls are also always full , the vent pipe is in the middle hidden , there is no hose connected there , it might not be necessary but for the sake of testing we will put a hose and do that blow test sometimes in the future, i have work and school in monday until saturday

[juliusmichaelhonrada]

after we cleaned that idle circuit and installed a smaller more restrictive 45 degree angled pod filters , it would idle now at 1300 , only small fluctuations now from 1300-1500 , huge improvement

[juliusmichaelhonrada]

We did every test on the carb, fuel flows through the circuits and jets when i blow on the vent hole.

After 4 spark plug checks . it is wet with oil we cant be wrong the smell , its new oil , P.O said he did an oil change before it was sold to us.
Spark plug electrodes is wet with oil but theres no smoke in the exhaust.

So we decided that we will tear this engine down in sunday , any tips , thoughts , ideas on what to look for and specialty techniques on removing or assembling something will be appreciated specially on the valve springs?

[Z1R rider]

One of mine had set for a long time (years I'd guess) before I got it, it ran but was down on power compared to the rest of the 250's in our pack. When I tore it down I found the the cylinders had HUGE rust pits on about 1/4 of their surface, it's amazing it ran as good as it did! Also make sure the rings are not stuck in the ringlands, especially the oil rings.

[Motofool]

Originally Posted by juliusmichaelhonrada

.............
So we decided that we will tear this engine down in sunday , any tips , thoughts , ideas on what to look for and specialty techniques on removing or assembling something will be appreciated specially on the valve springs?........

Before full surgery, I would do a compression and a leak down test with the cover of the valves removed.

Here is how:
http://www.dansmc.com/compression_test.htm

http://www.dansmc.com/leakdown.htm

Even if you don't have the gauges and adapters, a rough test could reveal leaky rings or valve's seals/guides, even a perforated piston.

[juliusmichaelhonrada]

Lower connecting rod bearing on the left cylinder is fcked, I cant believe this is possible , the engine is so quiet and theres no smoke in the exhaust

Link to original page on YouTube.

[juliusmichaelhonrada]

As of now we are still struggling to remove the flywheel , our tool didnt work the jaws just slip and we also dont have the socket for the clutch basket btw anyone knows the size?





Head assembly:


Block assembly:






Pistons:







Head gasket:

Base gasket:

[juliusmichaelhonrada]

What does a connecting rod bearing failure do to an engine?
Does it cause low compression?
Oil to the cylinders?

I guess the piston didn't hit the valves because the spark plug tang would be compressed and there will be 0 gap , but that never happened to the 4 spark plug checks we did only oil was present most of the time.

ALSO, when we removed the 7 bolts that connects the head to the base , there is a very foul odor like hydrogen sulfide/rotten eggs, i dont know what the f, was that , and also poking around the oil holes in the base, on the left cylinder holes the oil smells like rotten eggs , while the oil in the right cylinder smells good(new oil) , can anybody shed some light theories , anything , i want to understand the mechanics completely

[Motofool]

Originally Posted by juliusmichaelhonrada

What does a connecting rod bearing failure do to an engine?
Does it cause low compression?
Oil to the cylinders?

I guess the piston didn't hit the valves because the spark plug tang would be compressed and there will be 0 gap , but that never happened to the 4 spark plug checks we did only oil was present most of the time.

ALSO, when we removed the 7 bolts that connects the head to the base , there is a very foul odor like hydrogen sulfide/rotten eggs, i dont know what the f, was that , and also poking around the oil holes in the base, on the left cylinder holes the oil smells like rotten eggs , while the oil in the right cylinder smells good(new oil) , can anybody shed some light theories , anything , i want to understand the mechanics completely

It does nothing else than destroying the bearing and having metal particles going everywhere they can and over-heating the oil.

It causes low compression because the compression ratio is reduced.

https://en.wikipedia.org/wiki/Compression_ratio

It does not cause oil to the cylinders; you still have to determine what was causing that (oil rings or/and guides/seals of valves).

It should not have caused damage to the valves.

The smell comes from oxidation caused by the extreme temperature/friction/hammering pressure that develop around the damaged bearing once it loses its hydrostatic lubrication.

http://www.machinerylubrication.com/...analysis-tool-

https://en.wikipedia.org/wiki/Fluid_bearing

[Triple Jim]

Man, that's a lot of big end bearing play from the failure. You're lucky the piston didn't hit something. I had an outboard motor's big end bearing fail and the first symptom was the spark plug gap mysteriously closing itself.

[Mohawk]

That left piston was hitting the cylinder as indicated by the witness marks (the shiny areas) on head & piston. The rotten egg smell will be the shell bearing over heating, the oil being different per side would indicate an oil blockage to the left side. The amount of play may indicate the whole shell bearing is gone & its running rod on crank, so the crank may be toast.

[juliusmichaelhonrada]

So we found out that you can split the engine without removing the magneto and the clutch basket because the case has the split horizontally not vertically...

we destroyed 1 leg of the clutch basket and still the nut didnt came out we will TIG weld it.

CON ROD WITH THE DESTROYED BEARING:









DAMAGED PLAIN BEARING:









CRANKSHAFT:





PINK PAINT?


NO OIL FILTER ON THE BIKE!:



ONLY ran 11,429 KM ?



QUESTION IS I HAVE BIKES THAT HAVE CLOCKED WELL OVER 35,000 km+ but there was never any need to replace the connecting rod bearings? Can anyone tell me what went wrong from the above pics , is it lack of oil? dirt? or a combination of both exacerbated by the lack of OIL FILTER?

Most of all , what are the parts that we need to buy in order to do a solid rebuilt engine?
How do we rebuild this engine? any measurements on those bearing ? clearances? etc
We need some guidance , we dont want to buy good new bearings than 2 days later we need to tear down the engine again?

[juliusmichaelhonrada]

Found 1 intake valve on CYL #1(offending cylinder with the damaged bearing) is hard to get in and out of the head assembly could be bent .


Anyone can help me find out the part # for the bearings on my bike ? my crankshaft has the pink mark on it and my connecting rod has the white mark but i havent seen any color marks in the con rod bearings?

+ I HAVE MONEY NOW AND I AM MORE THAN WILLING TO SPEND IT BECAUSE THIS ZZR250 LOOKS SEXY!



+ E JUST BOUGHT A NEW 11MM SOCKET WITH 1/2 DRIVE , AND WE REMOVED THE OTHER CON ROD WITH THE GOOD BEARINGS FOUND A MARK ON THE LOWER CON ROD BEARINGS WITH THE GOOD BEARINGS IT WAS COLOR BLACK


+ My new theory is that the bearing got destroyed because of mis assembly or improper torque because i was able to remove the rod nut with a 1/4 drive ratchet while the other con rod nut needed a 1/2 drive ratchet and a lot of force to finally come off we tried removing it with the 1/4 drive and the square drive of our ratchet got twisted

[Motofool]

All that mess was caused only by deficient lubrication of those bearings.
It could be a number of reasons, but no filter was a terrible thing to do to that engine.
The loose nuts are the result of the hammering and vibrations.
You will need a repair manual and a torque wrench to do it properly.

[juliusmichaelhonrada]

Originally Posted by Motofool

All that mess was caused only by deficient lubrication of those bearings.
It could be a number of reasons, but no filter was a terrible thing to do to that engine.
The loose nuts are the result of the hammering and vibrations.
You will need a repair manual and a torque wrench to do it properly.

Thank you for the reply
Do have a copy of the repair manual ?
Were planning to buy another engine then take the parts , crankshaft , valves and clutch assembly to fix this engine.
Yeah we will buy a torque wrench too

[Motofool]

I do not have one, but you can find in the Internet one PDF to download for the pre-2008 Ninja 250.
You will have to replace many expensive parts, and still have to solve the smoking problem and flush all the lubrication conducts.
A whole replacement engine may be a more economic solution.

[juliusmichaelhonrada]

Originally Posted by Motofool

I do not have one, but you can find in the Internet one PDF to download for the pre-2008 Ninja 250.
You will have to replace many expensive parts, and still have to solve the smoking problem and flush all the lubrication conducts.
A whole replacement engine may be a more economic solution.

Thanks, but our bike have complete title/papers its rare to find a gray market bike with complete title/papers , most of them are smuggled , smuggled engines are cheap actually some one right now is offering us 7,000 pesos for a whole engine or around $140 also came from a running zzr250 but without a title/paper prolly smuggled its very cheap because these bikes are illegal they can never be registered .

We can swap the top crankcase with the engine # side to the running engine , or we can swap ng internal parts

[Triple Jim]

Be careful about swapping 1/2 of a crankcase. Some cases are machined as an assembly, so swapping one half could result in misalignment. I have no idea how these 250s were made.

[juliusmichaelhonrada]

Originally Posted by Triple Jim

Be careful about swapping 1/2 of a crankcase. Some cases are machined as an assembly, so swapping one half could result in misalignment. I have no idea how these 250s were made.

Yeah i heard about that color coding on the bearings and not all are machined at the same specs , that will suck for sure

[juliusmichaelhonrada]

found out that the crankpin with the bad bearings is 1mm lower than the service limit of 29.97mm measured using a good ol vernier caliper.

Found a machinist who can fabricate me a bearing , what do you think guys ? Is it feasible to just create a thicker bearing , then polish the crankpin and the conrod surface , then make sure the new bearing will have the clearances that is within the service manual specs?

[Triple Jim]

Crank pin to bearing clearance is critical. The manual says the clearance should be around 0.02mm, or in the neighborhood of 0.001" (one thousandth of an inch). The service limit is 0.08mm or about 0.003". I wouldn't bother with a repair unless it included grinding the crank pin on a crankshaft grinder to bring the surface back to cylindrical. Otherwise that clearance will be all over the place, not a uniform 0.02mm.

I know your situation is not the same as mine because of your location and shipping costs, but in my case I'd either buy a used crankshaft in good condition (eBay, etc.) or a $500-$600 used engine. Maybe someone here has a parts engine and can make you a deal on a crankshaft. Shipping of a crank by US Postal Service can't be too terrible... I regularly ship a set of three 2-stroke expansion chambers overseas for around $120, and they're in a 12" x 12" x 48" box that weighs around 24 lbs.

[Motofool]

Originally Posted by juliusmichaelhonrada

.....Found a machinist who can fabricate me a bearing , what do you think guys ? Is it feasible to just create a thicker bearing , then polish the crankpin and the conrod surface , then make sure the new bearing will have the clearances that is within the service manual specs?

The idea seems to be good, but there are some problems with that, besides what Triple Jim has explained above.

The useful surfaces of the crankshafts are hardened via superficial heat treatment (does not go too deep) and then are finished to final dimension in a cylindrical grinder (because the surface is too hard to cut and requires a finish that is as smooth as possible).

Your crankshaft went through an uncontrolled heat treatment while the bearing heated up to make the oil boil.

That area could be too brittle now and could fracture in use.
If you can cut it in a lathe, it is too soft.
Even if you find a cylindrical grinder of proper dimensions, the surface may not be hard enough for long time service.

https://en.wikipedia.org/wiki/Heat_t...tion_hardening

https://en.wikipedia.org/wiki/Grinding_machine

https://en.wikipedia.org/wiki/Plain_bearing

The connecting rod would need a steel split ring that is solidly anchored (in order to prevent axial movement after installation) to the aluminum of the rod, in order to accommodate the shell of the bearing.

Finally, you may introduce vibration and balance problems.

Save your money for a crankshaft, new or used in good condition.
These engines were assembled in your area; maybe you can find one locally.

[juliusmichaelhonrada]

Originally Posted by Motofool

The idea seems to be good, but there are some problems with that, besides what Triple Jim has explained above.

The useful surfaces of the crankshafts are hardened via superficial heat treatment (does not go too deep) and then are finished to final dimension in a cylindrical grinder (because the surface is too hard to cut and requires a finish that is as smooth as possible).

Your crankshaft went through an uncontrolled heat treatment while the bearing heated up to make the oil boil.

That area could be too brittle now and could fracture in use.
If you can cut it in a lathe, it is too soft.
Even if you find a cylindrical grinder of proper dimensions, the surface may not be hard enough for long time service.

https://en.wikipedia.org/wiki/Heat_t...tion_hardening

https://en.wikipedia.org/wiki/Grinding_machine

https://en.wikipedia.org/wiki/Plain_bearing

The connecting rod would need a steel split ring that is solidly anchored (in order to prevent axial movement after installation) to the aluminum of the rod, in order to accommodate the shell of the bearing.

Finally, you may introduce vibration and balance problems.

Save your money for a crankshaft, new or used in good condition.
These engines were assembled in your area; maybe you can find one locally.

I see, there is a Kawasaki assembly plant here , a brand new crankshaft cost about $400(20,000 peso) which is absurd considering that we got this bike for around $500(25,000 peso), i guess the best thing to do is buy that cheap engine.

The plan is to use that already running engine then we will just replace the top crankcase because we need the engine # to register it.

If the bearings with the different color coding have all the same outside diameter specs and the only difference is their inner diameter , then a simple swapping of all crankcase bearings is enough to fix it? I don't have any information regarding that matter.

Or how about we just erase the Engine # to that already running engine and etch the number of our engine?

[Triple Jim]

Originally Posted by juliusmichaelhonrada

Or how about we just erase the Engine # to that already running engine and etch the number of our engine?

That sounds like the best idea to me, although I'd never encourage any activity that's against local laws. Metal stamps probably produce a result that looks better than etching.

[ck.mecha]

Find a parts fiche for the ZZR250 and get the kawasaki part number for the crank. Then go find the parts fiche for the pregen EX250 and compare the part number. I can venture to bet they are the same, and EX250 cranks in decent condition can be found all day for under $150

[Mohawk]

So the crankcases are machined as one piece, so never mix two halves. If you use the existing case to keep the serial number & a replacement crank, remember you will probably have to replace the main bearing shells too, to ensure the crank has the correct clearances.

The old crank is toast the big end journal is shot, but I believe the crank is pressed up, so it may be simpler to get the crank rebuilt with a new big end journal pin. But I'd plastic gauge those main bearing anyway after the amount of contaminants found in the crankcase.

The main caus would appear to be over Rev on down change, causing piston to valve contact & initial bigend overload, that was compounded by the lack of an oil filter.
Good luck with the rebuild.

[juliusmichaelhonrada]

Originally Posted by Triple Jim

Crank pin to bearing clearance is critical. The manual says the clearance should be around 0.02mm, or in the neighborhood of 0.001" (one thousandth of an inch). The service limit is 0.08mm or about 0.003". I wouldn't bother with a repair unless it included grinding the crank pin on a crankshaft grinder to bring the surface back to cylindrical. Otherwise that clearance will be all over the place, not a uniform 0.02mm.

I know your situation is not the same as mine because of your location and shipping costs, but in my case I'd either buy a used crankshaft in good condition (eBay, etc.) or a $500-$600 used engine. Maybe someone here has a parts engine and can make you a deal on a crankshaft. Shipping of a crank by US Postal Service can't be too terrible... I regularly ship a set of three 2-stroke expansion chambers overseas for around $120, and they're in a 12" x 12" x 48" box that weighs around 24 lbs.

Where can i see your expansion chambers?

[juliusmichaelhonrada]

Originally Posted by Mohawk

So the crankcases are machined as one piece, so never mix two halves. If you use the existing case to keep the serial number & a replacement crank, remember you will probably have to replace the main bearing shells too, to ensure the crank has the correct clearances.

The old crank is toast the big end journal is shot, but I believe the crank is pressed up, so it may be simpler to get the crank rebuilt with a new big end journal pin. But I'd plastic gauge those main bearing anyway after the amount of contaminants found in the crankcase.

The main caus would appear to be over Rev on down change, causing piston to valve contact & initial bigend overload, that was compounded by the lack of an oil filter.
Good luck with the rebuild.

How can i confirm that the crankpin is just pressed , it doesnt look like my 2 stroke crankpin that has its other end visible in the other side of the crankshaft? This will give us many other solutions if we might not find a good engine...

My brother found another engine its an Eliminator 250 engine it looks like all the same except the primary drive gear ratio is different and the cam profiles?

[Triple Jim]

Originally Posted by juliusmichaelhonrada

Where can i see your expansion chambers?

Chambers: www.lakeserv.net/chambers
Electronics: www.lakeserv.net