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70cc / pressure blowing out of oil filling dipstick hole ( a lot even at idle )

11K views 9 replies 8 participants last post by  leegreens  
#1 ·
Whats up with that ?
Right side crankshaft seal i suppose ?
Do i need to split the cases to replace that seal and will that seal come with the seal package that dratv sells
 
#3 ·
Blowing air through that transmission vent hole ( using a small hose, obviously ) with the oil filler dipstick unscrewed is a piece of cake, no clog there and dude i'm not talking the is air coming out of that thing when it's running at idle, I'm talking some substantial psi is coming out of that thing. If the engine is hot then fricken hot azz air is coming out of that thing and the oil inside is so hot it's smoking.
Other than this, the motor runs great.............But whats going on with this compression leaking into the gearbox just aint, not, isn't natural
Oh, one more thing, it runs a lot better with the dipstick in rather than taken off, screw it in and tighten it down and the idle is smoother LOL..WTF
 
#7 ·
I had the same thing on my Xmas special. Found a bad head gasket leaking into the timing chain side of the cylinder. There was so much blow by the hose moved on compression stroke. The worn piston is most likely. There will be some air coming from the hose and oil fill just from the piston traveling up and down the cylinder. If the motor is hot then the air will be hot.
You need to take a compression test that will give you the info you need.
 
#8 ·
Thanks all, yep i pulled apart the top end, the piston is shot the hell out and rings were like non existent
I hardly thought that would be the case and I had never done a comprehension check for the same reason, the engine didn't smoke ( exhaust )
In any event I just ordered an 88cc kit from dratv
@fantastic70 ................The hose would move on compression stroke LOL
 
#10 ·
Good thread my Xmas special had case pressure. Just finished the build & it spits & sputters some times, idles perfect when warm. A lil blue out the exhaust until warm.
Its running like a about to be blown 2 stroke w the spit & sputter on the throttle crack. I bet i need a new top end too. Cuz its too clean to be a breather i dont think this thing ever touched dirt.