[SOLVED]Engine break-in....stalling...overheating?

just wondering if u can somehow prove that u are starving for fuel when hot ? how about measureing the fuel in the bowl cold, then again hot? or take the float bowl off when its hot to see if fuel flows from the seat?

just wondering if u can somehow prove that u are starving for fuel when hot ?

Yes that's a possibility now, maybe i'm not starving fuel and just overheating !

With the new settings ran very great in this morning (around 62F) then ran like crap now (around 95F sunny like hell) but it's wayyyyy better on idle.

In overall what i think is engine is simply too hot because when it wanted to die at a red light , pulled the choke half-way and omg 4-5k idle with no sputtering!

Anyway choke attempt was a good idea... it gave me a clue!


I think i must continue to increase jets!

regards,
laurent

hocbj23 wrote: I was getting fuel boil off at air temps over 90% on my KZ1000, and the beginnings of vapor lock. I lined the outside of my tank next to the engine with heat reflective tape(similar to NASA type material)and put double thickness around the petcock.No more issues.U said your cylinder head temp was 300 plus degrees on hot days?That sounds way hot.I have a temp gauge on my head and it rarely gets over 190 degrees.Oil coolers do work in stop and go traffic,just not as effective.I have a big Satrab cooler and my oil temp on very hot days is 210-220 degrees.I think the 10% ethanol is causing a lot of heat related issues for air and water cooled engines-JMO.bj

JC whitney has a fuel line insulator kit for 20 bucks

+1, didnt I say something about fuel boiling off a week ago ????/

JC whitney has a fuel line insulator kit for 20 bucks

+1, didnt I say something about fuel boiling off a week ago ????/

Fuel is boiling because of the very hot head temp...i guess that if i continue to increase jet size without making it lazy with overly rich, engine temperature will continue to drop and idle might be stable at red lights.

I made the same thing as JC whitney but bigger and more insulation oh yeah and no cost

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As soon a i will find out what happen to Z1Enterprises , sent 2 e-mails about the package which they supposed shipped same day +1 day (ordered last sunday)... normally with fedex max 2 days from NY to QC. No answer yet since friday AM... very weird.

Waiting my main jets impatiently!:laugh:

Anyway i will update the thread when I've changed the main jets and made (hopefully) progress in the problem!.


regards,
laurent

Okay here an update for the stalling issue...

Looks like its the fuel level that is not right...

www.kzrider.com/forum/3-carburetor/46394...arburetor-fuel-level

Dear Carbs expert ,

My gpz is giving me nightmares lately (more info on engine section, anyway)

Set the fuel level to 3mm on bench (at level), did a 1 hour test drive bike ok no stalling at red lights...happy i go to work then 10 hours after when its time to leave start the bike on the choke very hard to start had to pull the throttle and it looks like only 2 cylinders was running...

Managed to make it less worse and ran to home carefuly...

I decided to check the fuel level on bike (bike at level of course!) omg carb #2 fuel is too high by half inch and carb #3 too low by nearly half-inch too!

Double checked before on bench fuel level was optimal (No i didn't raise the tubing ) !


What's going on there ... are these BS34's cursed ?

Does not having a center stand play a role in there ? (cannot because of the headers)

My bike is always on side (except when checked the fuel level put it straight), do this upset floats?

regards,
laurent

In fact did the fuel level on bike straight not on bench and its better... start without pulling throttle and choke is right!

The bike still idle rough but maybe i suspect bad carb sync or idle not set correctly...

I think my tachometer is playing on me :ohmy: ... and depending at the angle you look it could be 1100 rpm or 1300 rpm...

With the digital infrared tachometer I've ordered on ebay i could put the nail in this hypothesis.

As for the carb sync, do the removal and re-installation often upset carb sync ?

Do pilot mixture play a role in the carb de-sync?

How often you sync your carbs guy, for me it's been 3-4 times since last month.
Trying for perfection, very hard to align everything!
I know I'm in the tolerance zone (from FSM) but want a perfect stable , continuous , non-oscillating, no rattle idle!

regards,
laurent

EDIT:

Would it help if i post a video of the idle issue i'm experiencing ?

Anytime I remove the carbs and re-install, I have to re-sync. They are not far off, but enough that a re-sync is a good idea. Back when I was doing o2 sensor based jetting changes, I had to re-sync up to 3 or 4 times a day. I got it down to a pretty good scinece by then so it went fast.

Theoretically, airscrew adjustments would alter the sync since it's air that is bypassing the throttle, but I haven't noticed it make much difference in the usual 1/4 turn range that I'm adjusting. I'm not sure what would happen with a mixture screw, but I don't think I ever noticed them make much difference on sync (especially since they should all be set close to the same anyway).

Thanks loud for the reply !

One more question... when in traffic... the idle is around 1200 rpm then after few seconds if i don't touch the throttle it will drop to 800-900 rpm and start to oscilliate to 800 - 1200 - 800 in a 5 seconds interval... if i give a tiny squeeze (1/32th) on the throttle it will go to normal idle (around 1200 rpm again could be 1100 my tach look unprecise) then after 20-30 secs drop again to 800 ... if i raise my idle with the screw to 1100-1200 when its at 800 rpm when i move the idle would be at 1500 rpm (way too high)...

At least it wont die like previously, rattle (cam chain or primary) like hell but at least it stay running!


Whats the prob doctor? :laugh:

regards,
laurent

Man that is weird.

If it was my bike oscillating like that, I would try to rule out the ignition timing.
I would warm up the bike, then fix the advancer with rubber bands or something to make sure the weights are not moving at idle. Then idle it and see if it does the same thing. If there is no change, then I guess it's carbs or vac leak I'd be looking at next (I realize you probably already looked for that til you were blue in the face ).

ELCouz wrote: Thanks loud for the reply !

One more question... when in traffic... the idle is around 1200 rpm then after few seconds if i don't touch the throttle it will drop to 800-900 rpm and start to oscilliate to 800 - 1200 - 800 in a 5 seconds interval... if i give a tiny squeeze (1/32th) on the throttle it will go to normal idle (around 1200 rpm again could be 1100 my tach look unprecise) then after 20-30 secs drop again to 800 ... if i raise my idle with the screw to 1100-1200 when its at 800 rpm when i move the idle would be at 1500 rpm (way too high)...

At least it wont die like previously, rattle (cam chain or primary) like hell but at least it stay run


Whats the prob doctor? :laugh:

regards,
laurent

ur throttle cable is binding, lube it

If it was my bike oscillating like that, I would try to rule out the ignition timing.
I would warm up the bike, then fix the advancer with rubber bands or something to make sure the weights are not moving at idle. Then idle it and see if it does the same thing.

Nobody mentioned that before, its possible! If spring are weaks advancer may play with timing...

Also where to check with the timing light? (never used a timing light , yeah i'm noooob :silly: :laugh: )

I have a KZ550 83 engine lying around... do you think it will fit [timing advancer, both transistorized] on my gpz 750 82? Same specs same advance ?

If there is no change, then I guess it's carbs or vac leak I'd be looking at next (I realize you probably already looked for that til you were blue in the face

I hope not, i've been crazy on the checking lately ... new intake boots, new airbox boots ... fun with wd-40...

Could a bad diaphragm in the carbs cause loss of vacuum (checked thought) ?
Is there a part i must look for my Mikuni BS34.. like o-ring somewhere that might create a vacuum leak...

Choke ... cough... enricher system could leak vacuum?

Its the only stuff i didn't check for leaks... because i'm not sure what section of a carb is exposed to vacuum!

ur throttle cable is binding, lube it

Highly unlikely, since its doing it without throttle cable installed but since i'm desperate ... oh yeah i'm lubing it!:laugh:

thanks guys!!!!

regards
laurent

whatever

Dumb question, I know, but are the vacuum caps on the carb holders? (there was a guy on this site a while back who didn't know they were needed) Ed