So I change the front tire and pogo seat bushing and I fire it back up and all of a sudden it's popping and spitting from the front cylinder. I'm quite certain the two are unrelated but the engine was running perfectly before the tire change. Anyway, tried getting it to idle and it was backfiring horribly and ended up fouling the front plug. Set the S&S Super E carb to factory settings and changed the plug. Fired up nicely but after a second it started blowing black smoke from the front cylinder.

Carb issue or head or rings or...? Where to start?

 

float level is changing -- the float has sunk and flooding the motor

 

Wouldn't a float issue cause both plugs to foul? This is just one cylinder.

 

if the manifold is connected to both cylinders - and it is

and you see the one exhaust pipe blowing black smoke, logic would be the other cylinders sparkplug has shut off, and most of the fuel is being drawn in to the one running

BUT i am not sure the valve adjustment has turned out ok

i am not trying to pick on the job you did BUT it ran fine -- you cleaned the carb and found nothing, you also adjusted the valves and the motor has issues it did not have before / and chasing the carb is not getting anyplace

so can you explain how you did the valve adjustment maybe someting small was over looked /// Just a guess -- jz

 

Sorry if I wasn't clear. I never did a valve job on this motor. O ly thing I've done is to adjust the carb after it began blowing black smoke out of #1 cylinder. Thanks for your help so far.

 

Mileage on the rings would make a difference. It also depends on what the front plug looked like when you pulled it. Are we talking carbon fouling, oil deposits...? Also, did you pull the carb? Or just spray it out? If you pulled it, did you look at the intake valves? Excessive build up on the valves screams valve seats/seals. Things to consider about shovelheads though, the front cylinder naturally runs colder than the rear, so an old trick is to run a hotter plug in the front than in the back.

To look at things a little...dimly though. If you did only spray out the carb... you probably just started burning off all the dirt and carbon build up in the carb. She'll puff black smoke and foul some things out pretty quick like that. But typically it would be out both pipes.

 

All of a sudden? One cylinder? Sounds electrical (coil, ignition, plug wires).

 

A whole lot of guessing going on here ( me too ) but it only takes a few minutes to run a compression check ... many little gremlins can pop up all at once ... broken rings ... valve springs ... guide coming loose in head ( very common ) ... lifter problems ( broken/missing bearing on lifter axle ) ... smoke out of one cylinder generally indicates a mechanical problem in that cylinder ... check the basics out and go from there.

 

i confederate i,
I know ya wouldn't think so but I've been told most of the time the rear cylinder runs cooler than the front cylinder.
I checked with a Raytek IR gun on a bike and the rear was, in fact, cooler.
But I did check only the one bike, one time.