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Discussion Starter #1
a friend of mine built a 450 smr motor over the winter
falicon worked the crank (welded/polished/maybe knife edged)
high comp piston
some head porting
pretty much the basics
stock bore/stroke


problem
motor is blowing a LOT of oil out of the crankase breather, from what i understand it blows so much that it fills the catch can to a certain point (maybe 1/4 full) then starts blowing it out of the catch can all over the bike.
last season the crankcase breather was plumbed to the carb and burned, but he re-routed it to the catch can
i havent seen it myself, gonna go look at it monday, but does anyone have any ideas before i go check it out
 

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RFS engines are sensitive to oil level.......I forgot where it was, but I read an article on proper oil fill.......cold, it should barely hit the bottom of the sight window....

I've had clutch problems and oil leaks from to much crank pressure if I run too much.....
 

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yup, sounds like too much oil, long wheelies can also result in coil coming back out the breather
 

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Discussion Starter #5
oil level is definitely out, that was the first thing we tried, ran it low, like significantly lower than is "normal"
anything else?
it just seems like rediculous crankcase pressure is being built up, cant figure out why
 

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Maybe a broken ring? did you do a leak down test?
Just grabbin' straws here.
 

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You should take off the clutch cover and see if the right cank seal has popped out, when this happens everything feels normal but there is ridiculous pumping out of the breather. If you run very long like that though, the seal 'spring' can come off and get chewed up inside the tranny.
 
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