1956 BMW w mikuni carb occasionally backfires on deceleration, sometimes singularly and sometimes in clusters. Can be deceleration from high speed (60-80 kmh) or from low speed (40 - 60 kmh). I'm baffled,is it timing, carb or something else?
2006-12-15 14:08:34 · 10 answers · asked by pgw1 1 in Cars & Transportation ➔ Motorcycles
sounds like your carberators are rich, take out your plugs see if they smell like gas
2006-12-15 14:15:25 · answer #1 · answered by lowrider6204 3 · 0⤊ 0⤋
It would more than likely be the timing. However, carburetor problems can cause this, too. How much wear is on the engine? How old is the carburetor? It could have some leaking gaskets. Check for leaks around the throttle plate, too. Sometimes the holes where the shaft goes through can be worn enough to leak.
This will cause an improper fuel/air mixture.
2006-12-15 14:18:26 · answer #2 · answered by expatmt 5 · 0⤊ 0⤋
--The backfiring is caused, due to a lean mixture in the carbs.
--Honda repaired that problem in the 80's with an "air cut" valve on the carbs.
--Kawasaki Vulcans of the 90's & 2000+ models cure, was to richen the idle mixture on the carbs.
--Locate the pilot screws on the carbs (idle "mixture" screw - not idle screw) and turn them out (counter clockwise) in 1/4 increments (turn them out 1/4 turn and go for a ride.
--Keep repeating until the backfiring clears up.
2006-12-15 14:59:43 · answer #3 · answered by guardrailjim 7 · 0⤊ 0⤋
A 1956 BMW? Wow, didn't know there were many left. Anyway, the problem is carb related. Need to rebuild and set a/f mixture idler.
2006-12-16 06:08:25 · answer #4 · answered by LifeRyder 4 · 0⤊ 0⤋
also, make sure your exhaust system has no leaks, a bad gasket or loose studs at the cylinder head will let in air and allow unburned gas to fire causing the backfire.
2006-12-15 17:31:12 · answer #5 · answered by webman 4 · 1⤊ 0⤋
gas fumes in the exaust pipe burning causes that popping noise on deceleration
2006-12-17 03:28:49 · answer #6 · answered by seth1993@pacbell.net 2 · 0⤊ 0⤋
Its lean, suckn air in around the throttle plate on decell due to high vacuume condition. mine does it occationally and it has never caused a problem.
Enjoy the bike!!
2006-12-15 14:42:21 · answer #7 · answered by prd2boft 2 · 0⤊ 0⤋
In brief , timing or carburetor might need adjustments
2006-12-18 17:53:20 · answer #8 · answered by Andie A. A 1 · 0⤊ 0⤋
ur tuning is wrong. u need a good mechanic to suit your bike to get it tuned properly.
2006-12-15 16:38:02 · answer #9 · answered by CRAKIN 1 · 0⤊ 0⤋
try getting your gas somewhere else first.
2006-12-18 18:54:54 · answer #10 · answered by onieone 1 · 0⤊ 0⤋