Topic: #4 carb blowing air out.

[Spanner 1]

I forgot you had that 700SC...... prolly the best bike Honda ever made ( closely followed by the 650 SC ! ).

Oh, and the blowing air issue... +1 with the bent intake valve not closing.

[JohnPayne]

Yeah, I would kill for a Nighthawk S. Pretty hard to find though. I think that bike was what got me into motorcycles.

[scottly]

John, is the offending valve on the front of the motor, above the exhaust pipe, or on the back of the motor, above the carburetor?

[JohnPayne]

Back of the motor. #4 right next to the kick start.

[scottly]

Hmm, don't know. If the missing valve adjuster screw were on the front (exhaust valve), then the blowing out thru the carb could be caused by the exhaust valve not opening far enough to release the pressure in the cylinder before the intake opens. (had it happen on a Corvair once)

[JohnPayne]

Yeah, exhaust side looks good. The spark plug looks perfect as well.

[Frankencake]

Is it spitting air on every cycle?  Is it a steady stream of pressure coming out of that cylinder?  Is it a simple popping sometimes?  Show a picture of the spark plug from that cylinder?  I'd really like to see it.