I was thinking that you too may have had the nut on the front pulley come loose as a few others have but as I re-read your post you say that pulling in your clutch makes it go away ? Take your clutch cover off and inspect.

 

yeah it's kind of weird. it happens either when I'm just slowing down, or when the clutch is HALFway pulled in, like when I engine brake. I'll check both. BTW - do we have a wet or dry clutch?

 

Wet clucth. Where area is noise coming from?

 

my bike does something similar. it makes a thuding sound and shakes when I engine brake sometimes. could this be from a loose drive belt?

 

I don't know. My belt is as tight as a drum.

 

I can't tell where it's coming from.

 

ok, I just pulled the pulley cover, and everything LOOKS ok. maybe I should check the clutch. Jusa asking, because Idon't have much experience, but what kinds of things should I be looking for?

 

Yes if the noise goes away when you pull in the clutch....its most likely related to your clutch.I would drain the oil and remove the clutch cover.Check the online service manual on the Yamaha-motor website if you have bought a paper copy already.

 

ok, I'll pull it open. Just one thing : could you tell me the torque settings for the bolts? Thanks. BTW - couldn't find a service manual online, yamaha has an owner's manual up, but it's not much use.

 

Have you checked your belt? Maybe there is a rock on it or you might run too much tension. Makes all kinds of strange sounds the slowing down...

 

you know, I looked at the belt and it almost seems TOO tight. do I really need the tools suggested to check the tightness, or can I eyeball it and be ok? Me and the Fiancee took a ride tonight, and decided it couldn't be the clutch. It happened whether or not the clutch was in or out. To me, it feels like a rotating mass that has a relationship with the wheels, so it could be the belt. I didn't see a rock, but I'll double check it.

 

Push down the belt in the middle. You should be able to get 1/2 inch play without having to push really hard.

 

It must be too tight. I put it on the jackstands, and burned the s**t out of my arm, and turned the wheel mself. it made the thump-click sound everytime it got to a certain point. How do I remedy this? BTW - maybe 1/8" movement pushing really hard.

 

Sorry about the online service maual....I saw a manual section on the site and assumed that was what it was now that they offer that cd version.You know what they say about assuming[/emoticons/emotion-2.gif] Sorry about that! If it does it regardless of the clutch then it could just be an issue with the belt? Keep us posted as to what you find.

 

well then its too tight, but sounds like if as you slowly move it and it still makes a noise at a certain point that there is another prob. 1/8" movement on the belt is way too tight though and i've read it can make noise when too tight. when moving it slowly can you hear where the noise comes from? have you checked to make sure nothing is stuck in your pulley (front or rear)

 

Proper drive belt slack, from page 3-47 of the service manual, is as follows:

On the sidestand
6 ~ 8 mm at 4.5 kg
(0.24 ~ 0.31 in at 10 lbs)

On a suitable service stand7 ~ 9 mm at 4.5 kg
(0.28 ~ 0.35 in at 10 lbs)

The level marks of the level window on the lower drive belt cover are in units of 5 mm (0.20 in). Use them as a standard for measuring
the drive belt slack. (Personally, I prefer to use a metric ruler)

Measure the drive belt slack when the engine is cold, and when the drive belt is dry.

The drive belt slack must be checked at the tightest point on the belt (rotate the rear wheel until this is found).

Measure the drive belt slack when the drive belt has been pushed with 4.5 kg (10 lbs) of pressure using a belt tension gauge (available at HD for $20).

 

Ok guys last night I adjusted my belt tension after I was done noise was still there when I spun the wheel backwards so I said forget it since I don't ride that way I won't hear it.. Went on to adjust clutch free play, didn't ride last night but I did today, no noise backing out no knocking when engine braking smooth and quite, put the bike on the stand turned the wheel backwards no sound anymore. thanx guys for the input....