77 Shovel backfire

[Phåråoh]

The bike has a 38mm Mikuni & K&N filter. It had TT pipes on it and the carb was tuned for them. I put the stock exhaust on and rode it all summer with no problems. Then, in the fall, I noticed that it was starting to miss under load at very low RPM. I put the bike up for the winter and figured I'd look into this in Spring.

In spring, I started it up. Warmed-up fine and I went to give it it's first ride of the new year. I got about 50' and it started backfiring terribly. I parked it and worked the throttle slowly up from idle. It backfired and sputtered through the whole range.

Then, it hit me... I never re-jetted the carb! I checked the plugs. Heavy black and un-burned fuel. I pulled the exaust. Very heavy carbon.

I cleaned out the top of the exhaust pipes and the ports as far as I could reach. I thought I might have to call a chimney sweep to get it all out.

Obviously, I'm not running it again until I get some advice.

I have a set of jets and also the carb manual... somewhere. Carbs are something I've never messed with and only know a little about.

So, I'm looking for some guidance. Is the reason for this problem most likely because I didn't re-jet the carb?

And, since there was so much carbon, is it possible my exhaust valves are so mucked-up they aren't seating properly now and will have to be pulled and cleaned?

I read the other recent post about the '81 backfiring and noted the coil issue. But, I'll leave the scenario as it is and rely on your advice.

[Phåråoh]

The question is starting to slip down the list and I'm the only one without a reply. Please take a moment to help. I'd like to be riding my bike as much as the next guy. Thanks.

[atrick]

My 78 glide does the same thing in the spring from sitting all winter and its just crud and dirt and bad gas from sitting all winter. Pull the float and clean it, Fire it up and it clears up, put new gas in it and run it at a little higher rpm to get all the dirt out of the jets and if that doesn't help you might have to pull the carb and really blow out the ports. I got a S & S Super B on mine. After it starts running right pull the plugs and clean them, I got a glass bead blaster so they clean up like new.

[nmaineron]

Shovels aren't that finicky with jetting especially on just a pipe change.Try looking around for shorts in your wiring especially your grounds and your main circuit breaker.You don't say whether it is an FL or FX but if an FL check your ignition switch.Don't ask me how I know!!Good luck

[Phåråoh]

It's an FL and thanks for the advice. I have an original manual and take a look at it to see if it covers electrical system tests.

And I'll start by cleaning the carb. Probrobly should re-jet it though, or at least have someone who knows about that stuff take a look.

Thanks again!