My 2000 has developed a bit of smoke on the decel. First thing that come to mind was the rings. What kind of reading should I be getting for compression?

 

I'm not sure on compression. You can do a search and probably find it. If it smokes on decel, it's most likely valve guides or seals. Crankcase vacuum is high when the throttle is closed and will draw oil in thru the guides. You might want to check your crankcase vent. Mine is located under the seat. Make sure it's clean.

 

Yea what he said...lol No seriously it is not likely thast it's the rings. more likely it's the valve seats or guides. You may also look at valve adjustment, it could be too loose.......

 

I was curious also on compression and did a search. Didn't really come up with an exact answer. There is a compression release that should be disabled by removing the valve cover. I saw readings of 125psi all the way to 245 psi with high perf pistons and cams. So there you go, I still have no answer.

 

Thanks guys, I'll check the breather. It did strike me as funny that it started so quickly.

Will the valve guides rob power?

 

compression reading on stock motor without disabling the compression realease mechanism on the exhaust cam will yield around 120psi.
but the best way to detect is with a leak-down test kit. small leaks that do not cause much to compression numbers can be identified with this method. a local bike shop can assist, and an experienced guy can help determine the source of the leak - i.e. piston rings or valve seals.

worn piston rings also cause excessive crankcase pressure, the breather relieves the inherent positive crankcase pressure that is caused by downward piston travel, and piston ring blowby will cause excessive amounts of oil to be burped out of the breather tube. check the tube for signs of this along with your smoke. but keep in mind a little oil from the breather is common due to the silly mounting position of the breather barb so low on the stator cover.

but are you sure the smoke is from oil? it could be from excessive unburnt fuel from a rich mixture that can also be enhanced by worn muffler packing over the years, or a worn/dirty/stuck carb float valve allowing overfilling of the bowl which in turn causes overly rich fuel/air mix. just throwing out more ideas...

 

I had been fighting a rich mixture problem and finally got that fixed and then this popped up. I'm pretty certain it's oil smoke. Our last ride was a muddy one and I haven't been on it for a few weeks and between the smole and it feeling sluggish, it got me a little concerned.

 

when i did a compression check on mine last year with the lever activated I got 180 lbs, then last winter i had new valves put in my head cause my intakes were burnt and the endgap in my rings were 1.2 mm really worn out, someone at tvi told me that a good motor with the lever activated should be around 225 lbs roughly, I have not tested mine yet as it runs awesome but I will have a leakdown test done this winter, just my .02 cents

 

oh yeah there is a bunch of past threads about the subject, dont be afraid to dig around

 

i got about 130psi without disabling the compression realease mechanism