QuestionWayne, I recently installed 2inch drag pipes with baffles and now when I twist the throttle quickly while cruising around 55mph, I get sputtering and black smoke and then it clears out and goes on. After riding approx. 100 miles the end of the front pipe a very black while the rear pipe is showing normal. Any suggestions? Also how do I tell what kind of carb I have?
Thanks, Andy
AnswerAndy,
If your carb is stock it would be a Keihin butterfly
type carb with a flange connection. Newer carbs
are also Keihin but have a constant velocity
chamber on the top and rubber hose type connection.
-Often if one cylinder is rich, it may be some
oil consumption rather than fuel.
A quick turn of the throttle makes the accelerator
pump squirt raw fuel into the engine.
-It is very hard to tune drag pipes as they
run best at higher rpm, above 3000 or so.
The backpressure of stock pipes is designed
to keep the fuel mixture from rushing out
the exhaust pipe and so they usually give
the bike more low end torque and easier
carb tuning.
-You might want to do a compression check
and possibly a leak down test to see
if the cylinder pressures are equal.
The front cylinder may be running cooler
and not burning the fuel as efficiently
as the rear. Check the plug color for clues
on each cylinders running condition.
-Usually running drag pipes results in a leaner
fuel mixture. You may want to rebuild your carb or
replace it with a newer CV type Keihin
or aftermarket Mikuni or other.
