87 zilla makes a noise when I accelarate quickly to 3rd gear or higher then ease off the gas a bit the engine seems to CREEK like an old rocking chair, give it a bit of gas it stops ease off again and it CREEKS again. Recently had the engine apart to do some trany work, never did this noise before. Still runs great with nose bleeding accelaration!!! Have wiseco piston. What does this noise? and how can I get rid of it? Is this detonating? Will a cooler spark plug fix the problem? Any help will be appreciated.

87 qzilla
87 qsport

 

I would put money on it being your rear axle bearings. Take a look I believe your will solve your problem

 

I think you're wrong. I had axle bearings fail before and this does not sound like that. This noise is definitaly coming from the engine when it decelerates slowly. I think it might be pinging but I don't know and I don't know how to fix it!!

 

Here is a clue I was just trying to help. It is what it sounded like to me. If you know so much about what it isn't then fix what it IS yourself and don't ask for help in here.:

 

I am a little leary to answer after you flatly told the last guy he was wrong. Considering your explanation, axle bearings and swing-arm pivot area ARE the most likely culprits. And it can sound like it is comming from the engine. The swing-arm bolt goes directly through the engine and can thus translate the noise TO the engine. Next time, rather than telling someone they are wrong, why not simply explain the situation better. It is not easy to diagnose a problem over a forum.

As far as your suggestion, detonation usually occurs the worst under the highest load conditions not when you are decelerating. Decelerating does, however, unload the rear suspension which is another reason to suspect a bearing problem in the rear.

If you are positive that the noise is caused by one or more moving parts inside the engine, it would be helpfull if you explained what you did to it. You mentioned doing some tranny work but what did you change or replace. If I had to venture a guess with the given information, I would say it is in the tranny itself. Other than the gears themselves, all engine parts work and spin the same for any given rpm. Therefore, unless the problem is in the transmission, the creeking should happen in every gear not just 3-5. You may have forgotten a washer at the end of a gear shaft. I did this once a while back and the inside of the case was eaten by a gear. You may want to drain your oil and check for metal particles.

 

It was not my intention to be rude and for that I apologize. I posted the question to get ideas to witch you responded and I thank you. You were both helpful. I took the engine appart to change the case sealant to fix an oil leak and with both your ideas this made me think back when I reinstalled the engine back in the frame that I had a bitch of a time inserting the long swingarm pivot bolt and I may have trashed the fragile bearings inside. I will check them soon. Thanks stormnorm