Can anyone help me out? I recently replaced the tranny again, got some work done to the head, and put it back together. Well the compression was way down, like 90lbs........that is all. It also had a rattle (hard to tell exactly where from) thought might be piston slapping.


So I just put in an 11:1 piston (.020 over) and there is still the rattle present.

Could this be the one-way starter gear? Could it be the cam? or what?

I thought about taking the one-way off and running it to see if it got rid of the rattle, but I don't know for sure if that will work since it goes behind the stator(will it work)?

 

Definitely find that rattle. I have heard of a few people whos one-ways have come loose or even sheered the bolts off, I would definitely check it out as an option. It could be the cam chain if the adjuster isnt working properly, it could be the water pump or even a broke clutch basket.


Why did your tranny go a second time? was it 2002+?

 

Are you saying you added a .020 piston into a cylinder that has not been properly bored? Did you get the balancer lined up perfect....it can be tricky. The head work could be causing problems.....what kind of head work was it?

 

The incompetent shop that did the warranty work repaced the tranny twice, both times putting the crappy 2001 gears back in it. The third time I took it apart myself and found 2001 gears and threw a fit and they (either yamaha or the shop)(they wouldn't tell me who was footing the bill) gave me more new parts, this time I made sure they were 2002 gears.

Now I just gotta find the rattle........

 

LOL....they won't tell you who was paying for repairs? Sounds like 1 of the flunkies screwed something up. You are on your 4th set of gears? Has the shift forks been replaced? What about my last post where I asked about a bore job? Was it done?

 

first, a .020 piston will not fit into a stock bore.

It was bored and honed properly by a machine shop(with the piston and box/instructions in hand)

I have had the head ported, valves ground and seats(?) recut.

The rattle was present before I took it apart to replace the tranny this last time, and yes I have the balancer lined up correctly. I believe, I went along with the factory service manual that I have. I also turned the motor over many many times by hand to make sure that nothing was binding up, and it wasn't.

It is really hard to tell where the noise is coming from.

Can I take off the one-way and run it? (I know I would have to pull start it)...????

 

yeah, the shift forks were replaced each time the tranny was(at least they said they were) But I know they were this time for sure, because I put everything in myself, everything except crank, and counter balancer and rod bearings? could these be the problem? I talked to a couple of shops and they said no way the bearing were bad yet, the noise also sounded(by description) to them like piston slap?

I am stumped.................

 

What is the compression now? The shop might have over bored it a little too much. Does it only make the sound in neutral? Mine makes a slight rattling noise in neutral and then quits when I put it in gear, even when its just setting there. It has done it since it was new. I have been told it is normal and is the cam chain. Nothing has broken yet! knock on wood

 

I put it back together initially with the stock piston and rings, this is when the compression was only 90lbs. Now it is like 150lbs.

No, not just in neutral, just about anytime, rev it up and let off the gas is when it is most noticeable.

 

Check your springs on your pipe. One of mine broke and i had a rattle like noise when i reved it.