2006-06-29 05:25:01 · 6 answers · asked by mhaley72 1 in Cars & Transportation ➔ Motorcycles
If your fuel air mixture is to rich (too much fuel) there can be a build up of unused fuel in the exaust system that pools and eventually explodes, causing a backfire.
2006-06-29 05:27:42 · answer #1 · answered by Anonymous · 0⤊ 0⤋
There are several reasons. You may not have the bike jetted properly if it is carburated. Jetting is typically set at the factory for sea level. If you live well above sea level you are probably running too rich or getting too much gas in proportion to your air going into the cylinder. The second could be that you have a cold air injector on your bike to meet California emissions standards. These cold air injectors pump cold, outside air into the exhaust ports which blows it out the exhaust pipes. This is done in order to "fool" the emissions testing devices so that the motorcycles pass California emissions standards. Additionally, if your pipes have a lot of back pressure due to restriction by bends, canister mufflers and baffles, etc, you can get a build up inside these devices which cause the left over gases to superheat and "pop". Removal of these can do a lot to stop backfire noises and also improve performance of the engine. Unfortunately, if you live in California, removal of these components can cause you to fail emissions tests if you do not know how to compensate for them. If you remove baffles, mufflers, and restrictive pipes, make sure you have the bike rejetted or properly retuned if fuel injected in order to make the bike perform at its best. Also remember that straight pipes, though improving your performance, can make your engine wear out faster if not properly adjusted for!
2006-06-29 12:35:33 · answer #2 · answered by viclioce 3 · 0⤊ 0⤋
Could also be a timing issue, if the valves havent fully closed when ignition occurs, the bike will backfire.
2006-06-29 12:30:41 · answer #3 · answered by NinjaRacer 3 · 0⤊ 0⤋
If its backfiring either the timing is off or inlet valve isnt seating.
Firing in exhaust is AFTERFIRE.
Too lean, no backpressure, open pipes, bad valve.
Open pipes generally loose power everywhere except max rpm, on HD sportsters you usually loose about 6bhp with open pipes, even with correct jetting, until you hit 6,500rpm
2006-07-02 11:57:46 · answer #4 · answered by 1crazypj 5 · 0⤊ 0⤋
"Viclioce" mentions fresh air injection or PAIR valves. Vacuum lines that operate these can leak and cause backfiring.
2006-06-29 12:56:17 · answer #5 · answered by tex 5 · 0⤊ 0⤋
usually it an overload of gas that hasn't been burnt..
2006-06-29 12:28:23 · answer #6 · answered by Vulcan 1 5 · 0⤊ 0⤋