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gasgasser

01 yzf426 front end rattle

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Just had the top end rebuilt but no it's developed a rattle from what sounds like the front top of the motor. Anyone got any ideas what it might be?

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If you still have a manual compression release, check it to see if it has free travel, and be sure the return spring on the lever at the head is still there.

If you had an aftermarket piston installed, the noise could be piston slap.

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yep agreed... cam chain tensioner and cam chain need replaced, and piston slap are the most likely what you need to focus on. Its sometimes really hard to diagnose where a sound is actually coming from, as the vibrations can fool you.

Back in 2000, I had a 1998 400f which developed a strange whining sound when it was reved up, much like a street rod car with a double cam chain. Took everything apart, never could figure it out.. .sold it.

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If you still have a manual compression release, check it to see if it has free travel, and be sure the return spring on the lever at the head is still there.

If you had an aftermarket piston installed, the noise could be piston slap.

Yeah I do have a manual comp release, and it's smooth and even with the cable disconnected it rattles.

Not sure if it's piston slap as it really rattles like a bag of spanners, not knocks. And it all seems to be comming fron the top area of the motor.

Any other sudjestions to check would be welcome

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Any luck bro... finding whats wrong ? what did you replace in the head ?

Nah, haven't had a chance to pull it down yet, and not sure where to look.

It's had a new piston and re-shimmed valves.

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Ok bit of an update, the new piston is a genuine one.

I think the cam chain adjuster was wound/forced up tight, I let it seat itself and the rattle is better.

I'm told the cam chain is new, so I'm guessing that the cam chain guides could be worn, does that sound right or stupid??

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Ok bit of an update, the new piston is a genuine one.

I think the cam chain adjuster was wound/forced up tight, I let it seat itself and the rattle is better.

I'm told the cam chain is new, so I'm guessing that the cam chain guides could be worn, does that sound right or stupid??

Typically the guides don't wear much. Mine are original with about 800 hours.

I would check your valves and see if ones a little loose. Sometimes shops set them a little loose since the valves tighten up.

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Typically the guides don't wear much. Mine are original with about 800 hours.

I would check your valves and see if ones a little loose. Sometimes shops set them a little loose since the valves tighten up.

Nah valves are bang on in spec, didi them myself, and checked 3 or 4 times since. Don't think valves would play a part as the noise is becomes worse if the cam chain adjuster is wound on to make the chain tighter.

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what about something weird like a frozen link in the cam chain ...or possibly the wrong chain..worn camgear teeth...did they replace the chain ? or was it on the bike when you got it ?

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