Carb spitting oil

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buzzkill

New Member
Aug 22, 2009
24
0
0
atlanta, ga
Carb spitting oil**Fixed**

Hey, I just put my MB together and got it running, I am running a 20:1 for the break in, The bike starts and idles fine but it will not rev and there is a white foamy oil spitting out of the carb when I hold the throttle open trying to rev it up, I put the clip on the upper slot on the carb to try and lean it out but it does the same thing with no differance at all, I also took the carb apart to see if eveything looked good and I see no problems, no sticking float or loose jet. The exhaust seems clean with no oil dripping out with minimal blue smoke, I'm not sure what to do and any help would be great, Thanks.

Nick
****FIXED IT****
 
Last edited:
GearNut

GearNut

Active Member
Aug 19, 2009
5,104
11
38
San Diego, Kaliforgnia
The only other thing I can think of is that the port timing is off between the intake manifold and crankcase (controlled by the piston moving up and down).
In your case, it being a new engine, this seems to be be a factory flaw.
The intake port is letting part of the intake charge flow backwards out the carburetor instead of only going in like it is supposed to. This is quite possible with a 2 stroke engine and one of the reasons why the reed valve assembly came to be.
 
B

buzzkill

New Member
Aug 22, 2009
24
0
0
atlanta, ga
Well its running good now, THE DARN KILL SWITCH, never would of thought that it could cause something like this to happen but when I disconnect it the bike runs great, hook it back up and it won't rev and starts loading up. My guess there must be some kind of resistance in the switch that is causing the engine to misfire, I know it was hooked up the right way, I had the yellow tapped into the blue wire going to the coil and the black wire was grounded to the frame. I just don't get it.
 
retromike3

retromike3

New Member
Jan 9, 2009
148
0
0
Beaverton OR
I just replaced the throttle Housing with Integral Kill Switch from Dax for about twelve bucks and it completely changed the way my engine ran. (I think the kill switch was shorting) Its amazing how something small like that can make a huge diffence.
 
Prasinos

Prasinos

Member
Dec 1, 2008
261
0
16
California
This happened to me before as well. The problem is that the kill switch wire is stripped or worn down somewhere allowing a spark to jump to ground. At low rpms its unnoticeable but when the magneto puts out a high enough voltage a spark jumps at this wire rather than at the spark plug. When the engine is not firing on every rev the carb can spit.
 
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