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Discussion Starter #1
Hello all,
I have an 89 FZR600 with 20k miles. It is a recent purchase and was fine when I aquired it. Two days after purchase, It was warming up and coming down from a rev i heard a sharp rattle, that sounded like a bearing or a timing chain. The noise did not repeat, and I was optimistic it would not return, and it never did.

However, it was ridden lightly for a few miles, parked, and the next day refused to start. Finally fired up but was running HORRIBLY and smoking horribly as well. [a white or gray smoke - it was dark out]. I could gas it all i wanted to but it would not rev at all for me. Finally it died and would not start again. The plugs looked good. Fearing the worst, I pulled the tank and airbox and cranked it with my hands over the carbs - three sucked and one felt like it was blowing out - to me this sounded like a broken timing chain and bent valves at best. SO, without an end for my compression checker small enough, I held my fingers over the holes, and yes it had compression. How much? Couldnt tell ya.

SO, I pulled the engine out and pulled the head. To my dismay, the heads were intact, valves were in good condition, and the timing chain looked good and showed no wear. Everything looked as good as a normal 20k mi engine should, except everything was COVERED in very thick carbon buildup. However the valves were still seated correctly. The rings look alright but not perfect. Cylinders are 99% free of scratches and there is little/no play in pistons. Carbs are very clean. I have pics if that may help...

I would rather not tear into the bottom end because, despite the one-time rattle, it doesnt sound like a bottom end problem.
Any thoughts?
Pete

PS: I trust the previous owner in saying that it has not had any previous problems. This IS a new development. Thanks!
 

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Oh yeah by the way...The carbon buildup and the smoke is probably from your engine running to rich on fuel.The excess fuel will not allow it to burn very well causing it to shut off on you.You will probably have to adjust the screws on the carbs to get it to stop running rich,or else you will probably have to get some new jetting.You will probably either have to scrape the carbon builup out yourself or use some kind of fuel additive to do it for you.I'm not sure what the rattle was you were talking about but hopefully it was just a one time deal and nothing serious.
 

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Knuckle Dragger
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Is the inside of the engine case was covered with carbon or the gas path was covered? (Gas Path= Intake through exhaust).

When you said three carbs sucked and one blew...I'm thinking stuck intake valve...just one. (Is this the 20 valve Genises engine?) I'd lay 90% odds on a stuck valve....bent, broken valve spring, debris fouling the operation, etc.

Are the cam lobes good all the way around? Although I really doubt this is a cam issue...it takes quite a bit of unlubricated operation before you wipe a cam flat....and you would be finding oil on the oil drain magnet.

Let us know more.

Blue Skies,
JJ
 

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Discussion Starter #5 (Edited)
I will post pics later tonight.

The carbon buildup was only in the combustion chamber [less cylinder walls], and out [exahsut etc]. The cams look like brand new as do the timing chain and gears. Yeah its the genesis engine with a buncha valves. :p I was told when purchased it has a Stage3 jet kit. If this is what caused the carbon buildup, how do people run different jettings without suffering the same problems?

I dropped the pan with plans to tear into the bottom end, and discovered there was virtually no grime in the pan, but to my displeasure there was a tooth from a gear. It is too big to be from a timing gear and it is not from the main drive gear [?] on the crank. This leads me to believe I would otherwise be having trans issues SHORTLY. I believe I may be investing in a used engine and taking my good ol sweet time on this rebuild.

Thanks so far, guys!
Pete
 

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second chimp in space
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vocallyeargasmic said:
^Gas can cause smoke?
yep, black smoke. Though it's not as obvious as water vapor on a cold day or anything. Unless it's really bad...
 

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Discussion Starter #10
Airmotive said:
Is the inside of the engine case was covered with carbon or the gas path was covered? (Gas Path= Intake through exhaust).

When you said three carbs sucked and one blew...I'm thinking stuck intake valve...just one. (Is this the 20 valve Genises engine?) I'd lay 90% odds on a stuck valve....bent, broken valve spring, debris fouling the operation, etc.

Are the cam lobes good all the way around? Although I really doubt this is a cam issue...it takes quite a bit of unlubricated operation before you wipe a cam flat....and you would be finding oil on the oil drain magnet.

Let us know more.

Blue Skies,
JJ
the problem i have with that diagnosis is that the engine refused to start before i tore it apart. i would assume that it would at least try and start if a valve or two werent functioning...
pete
 

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Knuckle Dragger
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vocallyeargasmic said:
the problem i have with that diagnosis is that the engine refused to start before i tore it apart. i would assume that it would at least try and start if a valve or two werent functioning...
pete
Yeah, that's a good point. I think you're right.

I'm interested to see where that tooth came from.

(A quick note: I'm not a motorcycle mechanic by trade, I take care of jet engines. I just enjoy troubleshooting and making runners out of non-runners)

That is a very sooted engine. Did he have an eftermarket exhaust on it? I know a lot of people will hop up their bikes, but when it's time to sell it they put as much of the OEM stuff back on it. If the original owner put a pipe on it and did the requisite re-jetting, then put the stock (or even another, cheaper aftermarket) pipe back on, it would cause a very rich mixture. That still wouldn't explain the blowing out the #3 carb. (Except in a truely extreme case called "carbon jacking". This is where carbon slowly builds up under a moving part (such as a valve), eventually preventing the part from functioning. However, I've never seen this on a motorcycle engine before.

On a seperate note, it's good to see someone who's note afraid to roll up their sleeves and tear into an engine. That attitude is rapidly becomming the exception rather than the rule.
 

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Gents
Dynojet kits run very rich andthe problem is that folks that install them have no idea what they are doing...This is an example of a very rich jetted engine
I agree that carbon under the valve will stop it from running and I have seen this in a couple of bikes, surprisingly enough, with Dynojet kits...
I would clean it up, put it together take it to a proper dyno room and have it jetted
The stage three kits ate the worst as they are jetted WAY too fat and remove the airbox which upsets the resonance on the intake side of the engine, complete ruining the drivability of the bike
All in the intrest of gaining that last fraction of a HP at full throttle
Go have it jetted properly. It'll be cheaper in the long run and you'll be happier with the bike in the end
Jim
 

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Discussion Starter #13
Yes, it has a Cobra F1s Can on it. I have no problem cleaning the carbon off of the head and pistons, getting a seal kit and putting it back together - HOWEVER - I am leary as to whether or not this will solve my problem; keeping in mind the engine would not run before I disassembled it.

Should i remove the valves/springs/etc and inspect them?
Pete
 

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Discussion Starter #14
BTW: I am looking for another engine to drop in while I am working on this one. Having just bought the bike, im ancy to get out on it! :-D So it would be nice to be able to take my time rebuilding this one - so if anyone has/knows of an FZR600 engine at a reasonable price, I would be greatful! THANKS!

Pete
 

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vocallyeargasmic said:
Yes, it has a Cobra F1s Can on it. I have no problem cleaning the carbon off of the head and pistons, getting a seal kit and putting it back together - HOWEVER - I am leary as to whether or not this will solve my problem; keeping in mind the engine would not run before I disassembled it.

Should i remove the valves/springs/etc and inspect them?
Pete
You might want to consider looking at the valves.I would also look into the tranny to see where that tooth came from...I'm guessing it is the transmission where it came from anyways.
 

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second chimp in space
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Did you completely rule out the plugs? It happened to me that the short ride after buying it fouled them enough that it didn't want to start later. They weren't exactly pristine to start with. They looked ok (very close to yours), but when I tested them they didn't spark. Looking at how much carbon you have on there, I'd be surprised if the plugs were totally clean.

If you have another bike you can test your plugs with that'd be nice. Maybe someone who knows more about wiring could tell you how to hook your coils up if you don't have another bike. I wouldn't use a car because it seems those produce a much stronger current (stronger spark over a larger gap, at least on my car). And look at the difference between your plugs and new ones.
 

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Discussion Starter #17
before tearing down the engine I grounded each plug one by one to the frame, and yes, they were sparking perfectly.

I pulled uppart the upper and lower crankcases and to my joy...
NOTHING! Dah... clean as a whistle. My father keeps telling me that it most likely wouldnt jump out at me, [the problem] but I am still getting discouraged. I did a quick check of the trans gears and still have not found a home for the *extra* tooth. It was late, I will check more tomorrow.

Also on the agenda tomorrow is to pull the rotating assembly out and examine it. I am frusterated because it's begining to seem like tearing into the engine wasnt worth it. Sure I can still put it back together, but I am aware that I will then have a fully assembled but still nonfunctional engine. Unless something catastrophic happened to the crank, I cannot imagine what else I could find that would cause such problems.

Durrr...
pete
 

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second chimp in space
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So you're only tearing into the bottom to find the gear with the missing tooth, right? I really don't see how anything could be wrong down there and show the symptoms you had, like good compression and such. Maybe the timing chain skipped a tooth? Does the cam chain tensioner work? I'm not sure how reliably you can test it now, though.

Good luck!
 

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Discussion Starter #19
I am checking the bearings and the crank from that suspicious rattle i encountered. No point in fixing the problem just to bust my crank or throw a rod in a couple hundred miles...

Yes, the cam tensioner was still good before i tore down. No, the engine did not jump time - 1 + 4 were at TDC like they should have been when the timing marks were lined up.

Pete
 
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