Two strange noises, can't figure them out

[lbo]

I wish I had wave files as it would be easier then trying to explain.

The first noise is a definite "pst pst pst pst" like an air leak that changes with speed/RPM. Not necessarily RPM's because the noise is there off throttle too, but it seems like RPM's because it gets faster and louder as I go faster even though RPM's are about the same. Although after 40MPH it gets louder and much faster. I had an old exhaust gasket that after I dremeled a little bigger it went away. But then the gasket leaked, so I just put a new gasket on and now it's back. So I really think it's exhaust related but haven't a clue where. My silencer (technigas type r pipe) was leaking grease/oil after I recently repacked it... I just took it apart, cleaned it again. Noise is still there and it was there before I re-packed the silencer and changed and modified my gasket. None of those things fixed it, it just got back to worse after I put a new gasket on. Maybe a tire? Rear tire is a new Michelin pilot sport so I doubt it.

The other noise sounds like it's coming from the CVT. It sounds like something spinning and it's cadence? changes from cha cha cha slow to cha cha cha fast and then chaaaaaaaa and it goes away. The cha cha cha starts at about 20MPH and goes to chaaaaaaaaa at about 40, after 40 or so it's gone.

Did I explain it well enough? Any ideas?

[90GTVert]

The first noise, that sounds like some sort of air/exhaust... check over the whole exhaust, replace the gasket if necessary. If visual inspection finds nothing, on a day with little wind or in a more enclosed area (with ventilation of course) feel around the exhaust while it's running. Of course don't burn yourself by touching it, but you should be able to feel the air escaping from somewhere if you have a leak. The fan sometimes makes it hard to tell in that area.

Checking tire pressures should tell you instantly if it's a leak there. I've never heard a tire pressure leak pulse though, and certainly not when sitting still.

If it were an intake related leak, I would expect a loss of performance/driveability.

The CVT noise... I had a bearing go bad and cause something I think is similar to what you describe. There's a bearing in mine in the CVT cover that the primary drive shaft uses for support basicly. It made a grinding noise. Best bet is to pull the cover and have a good look around. You should be able to tell if a bearing is going bad because they stiffen up, feel coarse or rough, sometimes completely sieze.

[Karl]

Ibo, that first one sounds like an exhaust leak to me, too. Could you double up on the gaskets and see if that works?

Or could it be an intake leak? Check the boots to and from the carb?

The second one. Does it sound like it could be the CVT belt rubbing the tranny case? Is it a metallic sound?

Karl

[lbo]

Thanks for the replies.

I have replaced the main exhaust gasket. The noise was minimal but there, then I opened up the gasket with a dremel because it looked restrictive and smaller then the inner diameter of my pipe. The noise went away but I dremeled too much and it had a leak. (oil around the flange and header) I bought a new gasket, installed it, and the noise came back stronger. The gasket between the pipe and silencer is worn though, and my silencer did leak. Maybe the noise is coming from the silencer, even though it's as sealed as I can get it? I could use a new gasket for this matching. It's just as loud or louder as before I messed with the old exhaust gasket. It almost seems as though it's pulse is correlated with the speed though not the RPM's. At WOT and top speed it's a very rapid sound.

The CVT area noise sounds like something is spinning/rubbing, then it picks up it cadence or speed as I accelerate, then goes away. Almost like something is spinning slowly and as this spin picks up in speed it goes away... make sense? Sometimes it will come back (after it goes away) while I am still accelerating and then go away again.

You mention a bearing going bad.... hmmm. The inside of my variator back plate shows a little bit of grease, very little, coating it ever so slightly. The kind of grease that is minimal but spread out from centrifical force originating in the center hole of the backplate. The seal behind the variator around the crank shaft "looks" ok as it's not ripped/torn or shows any leakage. I can turn the engine over with my hand and it feels smooth.

EDIT: Oh and I thought it might be the belt. Just installed a new belt no change. Will need to look at the carb and intake, although I notice no degradation in performance. The new exhaust gasket did help with acceleration though.

[90GTVert]

If you don't have a new gasket around for the pipe/silencer you can try smearing a thin coating of copper rtv on the old gasket assuming it is basicly intact (you'll have to clean it off when you get a new gasket though). You may be able to just use copper rtv with no other gasket for a good seal. Copper rtv can seal a turbo to a header with that amount of heat, so you should be OK if you wanted to use that method. You can also find gasket material in sheets at some parts stores if you don't wanna wait for one to be shipped, though Continental Cycles may have some around.

The grease around your variator is prob just from the shaft the variator is on. It is often greased.

When I was talking about the bearing going bad and feeling rough, youd put your finger inthe center and apply some pressure. Then turn your finger. You would prob never feel the resistance of the bearing I'm talking about by cranking the engine. I don't think I have a pic of the one I'm talking about, lemme look.

[90GTVert]

The bearing I was talking about would be in the CVT cover, but the shaft with the arrow is what actaully rides in the bearing. It's like a support system. Sorry, I didn't have any pics of the inside of my CVT cover.