03 YZ450F motor noise/rattle

I dis-agree with grayracer, the marks should be spot on, maybe the bloke you bought it off tried to adjust the valves and one of the cams is out, also be sure to torque the cam caps to specific measurements and in correct order (study your manual), also when your tightening the cam caps up be sure to check that the camshaft doesn't lock up by turning the camshaft over with each torque of the cam cap bolts, if this doesn't help a bit of $$$ towards your local bike shop is cheap insurance!

I dis-agree with grayracer, the marks should be spot on, ...
You're free to disagree if you like, but maybe since this timing mark isn't perfect, you can tell me where you'd rather put it. The red dots are your alternative choices:

camcopy.jpg

....does the tensioner always need to be replaced? i was thinking i could run it through the test specified in the manual and if it checks out OK, reuse it. is this acceptable?
The tensioners on the '03-'05 are very robust, and if it passes the test, I would probably reuse it. They aren't very expensive, though. If you're in doubt fork over the $40 or so for a new one.

Note that the cam in the picture appears very slightly retarded. This could be a result of wear in the cam chain, and the slight wear traces along the top/outer sides of the chain plates suggest the need to inspect your chain guides. They rarely need replacement, but you may want to look.

Regarding your loss of power under a load, see if this fits:

http://www.thumpertalk.com/forum/showthread.php?p=7451949#post7451949

in that photo it doesn't show the relation between the exhaust and intake cam, are they out by the same degrees? I don't mean to be obvious but is the cam chain fully tensioned when you check the marks?

what would thumpertalk be without high-performance four-strokes!

in that photo it doesn't show the relation between the exhaust and intake cam, are they out by the same degrees? I don't mean to be obvious but is the cam chain fully tensioned when you check the marks?

No, and yes. However, the answer to the first question is not always necessarily yes or no. In this particular case, the intake appears to be nearly perfect.

Now, since you say the marks should be spot on, what's your solution?

Judging by this photo taken at TDC:

http://c4.ac-images.myspacecdn.com/i...16399352eb.jpg

It looks like your exhaust cam is slightly retarded (i.e. opening and closing a little late). I heard of a guy actually slipping the cam gear. Since it is pressed onto the camshaft I guess it's possible if you ride it hard enough, or if it is not properly pressed in the first place... But the result is a bit of slack in the timing chain, which you can't see in the picture. Perhaps a new timing chain is in order.

Judging by this photo taken at TDC:

http://c4.ac-images.myspacecdn.com/i...16399352eb.jpg

It looks like your exhaust cam is slightly retarded (i.e. opening and closing a little late). I heard of a guy actually slipping the cam gear. Since it is pressed onto the camshaft I guess it's possible if you ride it hard enough, or if it is not properly pressed in the first place... But the result is a bit of slack in the timing chain, which you can't see in the picture. Perhaps a new timing chain is in order.

At the age of this bike, it's certainly time for a cam chain, and that could very well be what is making the timing mark on the exhaust cam appear retarded, due to the extra length of the chain run from the crank up to the cam. However, once the chain is fixed, and the cams rotate forward 2-3 degrees, the mark on the intake is going to appear to be wrong, advanced by that same amount. Then what? The cams are only adjustable in one tooth increments. Because of that, the marks need only be precise enough to get the right tooth lined up, so no more effort than that is put into stamping them.

As to the question of cam gears slipping on the camshafts, it does happen, but that leaves the cam gears looking like they are properly aligned, so this can be very difficult to spot unless the view of the lobes from the right ends of the cams changes dramatically. If you suspect it, look under the cam caps for signs of galling and seizure.

Judging by this photo taken at TDC:

http://c4.ac-images.myspacecdn.com/i...16399352eb.jpg

It looks like your exhaust cam is slightly retarded (i.e. opening and closing a little late). I heard of a guy actually slipping the cam gear. Since it is pressed onto the camshaft I guess it's possible if you ride it hard enough, or if it is not properly pressed in the first place... But the result is a bit of slack in the timing chain, which you can't see in the picture. Perhaps a new timing chain is in order.

A new chain in this particular instance would bring that exaust cam timing mark back even more (assuming the chain was stretched)

and the only way you could tell if the cam gear "Press" has slipped would be to degree the cams.....The gear doesn't change if the cam moves....

did you sort out your rattle noise? i got mine back after having a new cam chain and tensioner and she still making the same noise as yours. so it looks like I'm going to have to pull the head off and check it.. i hope this helps............

did you sort out your rattle noise? i got mine back after having a new cam chain and tensioner and she still making the same noise as yours. so it looks like I'm going to have to pull the head off and check it.. i hope this helps............

Thanks for the info, i was curious to hear how things turned out for you. My new chain came in today and i have to work tomorrow, so i am planning on changing it out on Sunday. While i was at the shop picking up the chain i was talking with a Yamaha mechanic that has an 04, he said the noise was probably coming from the clutch. leoninlux said the same earlier in the thread, he pulled the cover on his and it was toast. I am going to install the chain anyway its cheap enough. i also checked the valves and they were all fine. Good luck ill let you know if my chain does anything to lessen the noise.

Thanks for the info, i was curious to hear how things turned out for you. My new chain came in today and i have to work tomorrow, so i am planning on changing it out on Sunday. While i was at the shop picking up the chain i was talking with a Yamaha mechanic that has an 04, he said the noise was probably coming from the clutch. leoninlux said the same earlier in the thread, he pulled the cover on his and it was toast. I am going to install the chain anyway its cheap enough. i also checked the valves and they were all fine. Good luck ill let you know if my chain does anything to lessen the noise.

ok thanks mate let us how you get on

Well i replaced the cam chain an adjusted the valves it seemed to slightly lessen the noise but did not make it go away. when replacing the chain i noticed that i could move the flywheel slightly left/right and in/out, it is very little movement but its not rock solid. Ive heard of this happening on a guys CRF and he just continued to ride it but am assuming that the crank bearing should be replaced to resolve the movement, or should i just ride the :thumbsup: out of it until im ready to rebuild it, which by the way my check books looking could be a while.

Well i replaced the cam chain an adjusted the valves it seemed to slightly lessen the noise but did not make it go away. when replacing the chain i noticed that i could move the flywheel slightly left/right and in/out, it is very little movement but its not rock solid. Ive heard of this happening on a guys CRF and he just continued to ride it but am assuming that the crank bearing should be replaced to resolve the movement, or should i just ride the :banana: out of it until im ready to rebuild it, which by the way my check books looking could be a while.

hi mate my bike got the same noise like i said earlier i also changed the chain and checked the valves and mine still makes the same noise, my local mechanic has said to ride it and it should be OK untill it gets a lot worse. but like your self im still worried about it

You shouldn't have ANY side to side movement on your Flywheel/crank-axle.......and really not any in and out as far as that goes...

That would account for all the noise...It must have a worn-out crank bearing..Start the bike up and put a long screw driver or stethoscope on the case nearest the main bearing and if that bearing is bad you will definitely hear it....

if it is the bearing what will happen if i continue to ride it?

It may likely seize the crank shortly if you continue to ride it. I dont have alot of experience working on bikes, but with cars/trucks and farm equitment I do. I wouldnt ride it, Id be bringing it to a shop.

That thing is loud, mine is really quiet comprared to yours....

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