Ive noticed a clattering, just above idle. Ive seen a couple of threads that referred to the balancer key. Did it make a noise first? It doesnt seem to come from that side of the engine. But that doesnt mean anything though. Id really love any input on this, this noise is a little unsettling. If anybody has any experience with piston rattle on these bikes Id like to hear about it. It seems to run fine, but the rattle seems either new or more noticable now.


is the bike in motion ?


That can't be a good sound. This may sound like a silly question, but are you sure it's not chain slap (have you had the 4-stroke long enough to notice the chain slap)?

Sitting still, just slightly reving the engine off idle to approx 3500 rpm im guessing.

Sir thump, ya I know about the chain slap, I got a TM design works buffer and guide. Chain slap now heard by other riders and spectators, Senators Congressmen and women, I dont think anybody hasnt heard my chain slappin now. Contemplating, taking that thing off.

Man oh man

Not Sure Pal, I have not noticed that with mine, Why I asked if in motion, mine was chain slap and the Rear sproket was coming loose.

But Then Again I am pretty tone deaf ask my Wife


ShawnMC : This is just a guess but could it be loose valves? When was the last time they were checked?

If it's loud and sounds to be coming from the bottom half of the motor then I would take take each case cover off (starting with the right side) and look for things like a loose clutch inner hub or basket, loose flywheel, etc... At least that's the best starting point that I can think of.. If it's coming from the top or top left side of the motor then check things like the cam chain tension, valves, etc.. I hope this helps, let us know what you find when you figure it out!


Shot in the dark but maybe the Waterpump may be going south.

Dead seriuos about this, Take a long neck Screw driver, place the flat head side on the suspect noise area (I.E. Waterpump Housing) place your Holding thump on the round end of the Screw driver Place your ear on your Thump. This acts like a cheap stethiscope and it works. You should be able to pin point the noise location with this.

I am not kidding it is a very old trick I learned. Hey it beats getting guesses from a forum :)

PS ya the bike needs to be running and you may need someone to twist the grip to 3500 off idle to pick up the noise best

[ April 02, 2002: Message edited by: EgoAhole ]

Hi Shawn, After replacing 3 keys, I'd bet that is the problem. Just remove the right side case and check the slop in the drive gear from the crank to the CB. If you replace it, I'd make one (they last longer than stock) and make darn sure you tighten the bolt that holds the gears to the crank very well. The screwdriver trick that was mentioned is a bit misleading because to me the sound is like a loose timing chain, but it is very pronounced if you put the screwdriver to the clutch cover to listen. It should make noise at all times. Hope this helps.


Strange part is, it only does it at a certain rpm. If I rev it harder, it goes away, when its idling, its not overly noisy. I guess Im going to have to tear into it.

It's probably the CB key (a common problem on the '00). Clattering is a good way to describe the sound, and the sound can change a bit with different RPM's, but it depends on how much slop you have.

When I replaced it the second time, I tried to wedge something between the gear teeth so I could get a little torque on the nut, but the CB gear teeth look fragile, so I didn't force too much.

If it loosens again, I'll try using air tools to tighten it (after installing a new key and washer).

[ April 02, 2002: Message edited by: holeshot ]

thanks holeshot, Ill give that a look tonight. I hope, I hope, I hope thats all it is.

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