HELP!!! YZ426F burning oil - what could it be??

nikki

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#1
The '01 YZ 426F has been burning a lot of oil as of lately - and I was wondering if this is normal or if there is a problem?

A few weeks ago - it took a whole quart of oil. After 2 MX races (approx. 1-1.5 hours on the bike in the 70-90 degree weather) it took another 1/4 to 1/3 quart of oil.

We are thinking that maybe a ring is broken or shifted out of place? Not really sure - 4-strokes are pretty new to us. Anyone else have any suggestions of what the problem might be - or is this normal when the weather gets hotter??

The bike is completely stock with about 30-40 hours on it.
 

CRGuy

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#2
Revenge of the two-stroke?
No actually your ring's may have just worn out. Replace the ring's and the piston and you won't be a smokey 4 stroke. When you tear the head off you will need to clean the valve's and port's as well as the pipe to get your maximum flow back. The oil probaly is collecting and you will lose power if you don't clean everything when you put the new piston and ring's in. Sheesh now we sound like two-stroker's with the changing of the piston and ring's LOL.
CRG
 

Mark C.

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#3
Could just be worn or siezed piston rings. If tho the rings look fine then make sure the vavle seals are sealing properly. good luck :)
 
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CRGuy

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#4
Mark C- The oil comes from the crank case not from the valve's. The valve's would have nothing to do with her losing oil. I think that the ring's are really worn and you need a new piston and ring's.
CRG
 
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#5
Nikki - If it's 30-40 race hours then the rings are overdue for a change. Valve seals are also worth looking at. A leakdown test would give you a clearer view of where the problems are, and the overall condition of the engine.
 

Mark C.

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#6
CRGuy- I believe from my experience doing a topend on a XR that the oil spits up from the crankcase to where the cam chain, rockers, valve, etc are at the the top of the head. Rich also mentioned vavle seals. If im wrong then im sorry :eek:
 

CRGuy

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#7
I didn't know that the oil would splash up. I know that the cam chain is there but normaly you won't burn any oil from what I've seen. I have owned a thumper before but never had a problem with losing oil.
CRG
 
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#8
You two guys might want to consider taking a close look at a service manual and see exactly how the oil is pumped through a four-stroke engine. It might clear up some misconceptions. You can learn a surprising amount from READING the service manuals for various types of engines, rather than just using them for a quick reference. They are some of the best books you'll ever own.
 
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#9
Are you sure?

Not trying to be a wise guy but, are you checking the oil after running the bike? You MUST, the oil will drain from the frame into the motor and you'll think, your low on oil.

When you drain the motor are you getting more than 1.8 quarts? You wouldn'
t be the first to overfill the bike due to not checking, after warning.

vetwfo'er
 
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#10
Whoooof, thanks Vet, I was reading down this post praying someone told the poor guy to run the bike before checking the oil. When you say your burning oil is it cause the bike is smoking or becuase the oil level is off the stick? When motor oil burns a qt at a time, there is some smoke and a lovely smell of Cheveys in the air. :) . I agree on reading the book cover to cover. Never mind feeling like a geek cause you read service manuals like a love novel, we are with you man! :cool:
 

SFO

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#11
It takes an evening to pull the top end, including draining a six pack.
Aren't you curious about what's inside?
I had alot of fun pulling mine apart.