burning oil

hi guys just a quick one i have recently got a ys450f its my first bike of this style as i always ridden road bikes so i don't know much about these at all how there supposed to sound ect.

today i noticed a little blue smoke from the exhaust and you can smell it burning and my engine sounds a little noisey.

also how u check the oil in these is a pain in the arse it docent seem to give me a reading yet i have put oil in.


whilst the bike was running i thought ill put a bit more oil in and see if it quietens the motor down but soon as i took off the oil filler cap it was blowing air is this normal?

What year model?

2003 yz450f grayracer

just wondering if the piston rings have gone and its burning oil but I'm not sure what these are meant to sound like all my road bikes are smooth and quiet this aint so I'm unsure if its a fault or it does sound that way

It is absolutely normal for air to pulse in and out of the filler on any YZ450 while it's running because it opens directly into the crankcase, which is, of course, exposed to the underside of the piston.  It moves 450cc of air around underneath it just like it does on top.


The bike is also a dry sump lube system, so the oil level indicator (dip stick) is in the tank where the oil is stored during operation, in this case, the frame. 


Read up and follow the included links: http://www.thumpertalk.com/topic/746100-first-4-strokehelp-please/#entry7615908


In good health, the bike should show no significant oil consumption over 5-6 hours of run time.  It's likely that yours need rings and possibly valve guide seals.  Figure on replacing the piston as well, and have the cylinder professionally inspected/measured.

thanks for the reply yes if I'm doing the rings I'm going to get it all done piston,rings,valve check and re shim if required are these generaly noise machines?

just watched a few vids seems mines just the same as everyone else. can someone help what piston do i buy do i have to strip it out and measure or can i just buy one then fit at a later date iv noticed theres a,b,c,d what is this? 

New Yamaha.  There's only one size piston: 5TJ-11631-00-00

thanks grayracer

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