Thread: re-jetting for different backpressure-why?

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Originally posted by southerner


Here's something else that is unique to bike carburetors, thay dont have accelerator pumps or circuits in the carburators, mainly because the engines dont lug arount as much weight as cars. Just my 80 cents worth. S

Not to be picky or step on anyone's toe's, but actually Harley factory carbs and some aftermarket carb's do have accelerator pumps. I disconnected mine and it ran like crap. Typhoon had the best explanation about the signal strength. One underlying cause is the fact that Harley's factory setup is very lean. An attempt to meet emission regulations I was told. As a rule Factory Harley's are very restricted on the intake side (air cleaner) and the exhaust side. Significant gains can be made with free flowing air filters and exhaust. Just my experience.

Originally posted by DennyW
Southerner, I wouldn't say that. My stock type 82 Honda cb650 has 4 carbs. The inner 2nd carb has a standard acelerator pump installed from the factory. As do many others. You must be thinking of something else.

Yup, All the ring ding 2 strokes and singles

How does one know how much back pressure they have?