Why Does My Harley Backfire?
My Harley Davidson starts and idles great, but as soon as I give it any throttle to speak of it will spew fire and pop from the exhaust.
It sounds terrible, is very embarassing and I am wondering if it is hurting the engine.
Thanks in advance for any help you can give.
Our Answer
Robert....it's very difficult to answer a question like that without seeing the motorcycle or being able to observe it. I would have to guess that you are probably experiencing a rich condition to some degree. Depending on the bike you may need more accelerator pump or you may need some work on the PCM. Too many variables.
I'd like to help but given the information, it's hard to say. We would need to know whether it's been modified in any way...did you install cams in it? Any engine work done recently? How does it run the rest of the time under load? Etc.
January 22nd, 2009 at 7:53 pm
Burning to rich
January 24th, 2009 at 5:54 pm
Cool.
It could be an ignition timing issue, running a bit rich, or even a valve timing issue created by a littel bit of exhaust valve overlap.
Most likely just running a little rich. No real problem with that and can be adjusted to lean it out. Don’t go too far though. Rich is okay, too lean can be catastrophic.
Besides people pay good money for flame thrower kits. They’re cool at night.
January 28th, 2009 at 1:48 am
50 yr old engine technology
January 29th, 2009 at 12:55 am
PROBALY RUNNING RICH AS YOU HAVE BEEN TOLD .BUT DONT LISTEN TO JEFFYB HE PROBALY RIDES A JAP CAN.
February 1st, 2009 at 1:25 am
Good lord, adjust or rejet your carb, your running way too rich.
February 2nd, 2009 at 7:30 am
You did say type or year, efi or carb, soanyway if you get to much excess fuel or oil in your exhaust the heat from the pipe will cause cookoff and inite causing a flame, causes: jetting,blowby,or evensticking valve,normally on a H-D if you have drags and are a little rich it blow it out and not pop or flash till you let off, burning what is left
February 4th, 2009 at 9:11 pm
ive got no idea, but when you find out let me know, maybe i can get my yamaha to do it
February 8th, 2009 at 7:48 am
Ok here is the correct answer, and rest assured that this will not be expensive. I had this exact same problem just weeks ago on my old shovel head.I tried everything, new plugs, wires, carb intake boots, timing, lifter adjustment, and it still did this only when i reved it up. it idled fine.Your jets are fine if it ran good before so don’t listen to all the garb.Here is the answer bro believe it or not I am 90 % sure it is your key switch. It don’t get enough power to the coil because they go bad from vibration. Here is how to check, run a jumper wire from the hot battery post to your coil and see how it runs then. If it runs good then, replace your switch they are 23 dollars. Do also let me know what you find, I’m at