Hello gang, new guy here.....2000 FLHTCI with 34k miles that I snagged a couple of months ago. I will get an occasional backfire between shifts, as well as at a stop light - light turns green, blip the throttle, then release clutch. This quick blip gives me the occasional backfire. It doesn't seem to do it in the morning when the ambient air temp is only 80, but in the afternoon when it's 100* plus I'll get the backfires. My cruise home from my shop is 10 miles, 55 - 70 mph.

Is this a normal Harley thing? Performance seems just fine.

 

 

If you have a carbureted bike has it been rejetted? Stage 1? This is the first things I'd look at. Next I'd check for an intake leak and exhaust leak. Do a search for the instructions.

Good luck and I hope this helps.

 

It is fuel injected, with a Power Commander and a Stage 1 kit.

 

The system is detecting too much O2 and is pumping too much fuel in. A simple thing to check first off are your exhaust head bolts. If they're coming loose your bike will behave just like you're describing. Mine was doing that on the weekend. tightened up the nuts on the front pipe and the backfire went away.

 

I agree with bowmanvillejim. . Check for leaks at exhaust. If the nuts are tight you can use smoke around the ports with the bike running to see if exhaust gas is escaping. If not he it's on to the intake manifold. I use carb cleaner and spray where the manifold meets the head It can die or slow the engine down.

That being said, on my carbed 01 Sportster. It reall didn't do any of these things but when I finally got fed up with the popping I pulled the intake manifold and the rubber gaskets were all destroyed. I replaced them and voila, no more pop.

I hope this helps.

 

Thanks for the tips. I'll get into in next week.

 

Is it a definite backfire, or decel popping? First thing on any EFI bike is to check for stored trouble codes. Check the simple stuff suggested here. Since it seems to be temperature sensitive I would check out the engine temp sensor as well.

 

exhaust or intake leak

 

I finally found time to check out these suggestions, and found the exhaust flange nuts on the front cylinder quite loose (the rear was tight). Rapping it up to 4k in my garage and letting it fall to idle presents no more popping/backfiring. If it wasn't 112* I'd take it for a putt. Thanks everyone for the suggestions, hopefully this was the issue.