Air blowing out of air filter?

I have a Sachs 505/D on my 79' G3. It is having trouble idling. I've done all the basic stuff: messed with the idle screw, sprayed for air leaks, adjusted the throttle cable, tried a completely different carb off of a working ped, tried it with and w/out the air filter housing, etc.

I'm going to upjet as well because I think the exhaust on the ped is not stock. It is way too loud to be stock so maybe it's been modified internally (no idea what previous owner did to it). I am also going to adjust the clutch because it's not catching correctly.

The strangest thing of all however is that when the motor is running (when hold the throttle) air is actually blowing out of the air filter housing! I would assume it should be sucking in?

Re: Air blowing out of air filter?

I found a previos post with a similar issue and it turned out that the piston was installed upside down

Re: Air blowing out of air filter?

Downhill Harvey (OFMC) /

The strangest thing of all however is that when the motor is running (when hold the throttle) air is actually blowing out of the air filter housing! I would assume it should be sucking in?

Piston port engines do that. Pic of pipe?

Re: Air blowing out of air filter?

wow, didn't know that. how is it getting air then?

The pipe looks just like a stock one. I'm assuming the PO took a baffle out or something cause it's loud

Re: Air blowing out of air filter?

Downhill Harvey (OFMC) /

It just exhales a bit, then inhales, you just can't notice. Put a rag near the carb inlet (hold on tight), you'll see.

Re: Air blowing out of air filter?

Piston skirts on d engines are asymmetrical and will block the transfer ports f installed upside down. Last time I had that motor apart, it was in right side up. It's worth checking though. I don't know what all happened to it after it left my garage.

Has you checked to see if the decomp is leaking? What is your compression gauge reading?

Re: Air blowing out of air filter?

i'll check the decomp and compression next.

thanks for the advice

Re: Air blowing out of air filter?

turns out the idling problem was due to an air leak at the intake. all is well now

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