Snakepit said:
Bottom, midrange, and top end. I don't know what you have it term of improvement, but if you are reasonably stock then what you have is not bad. If on the other hand you have a hot cam and complementary components then the big pumper may bring out the best of what you have.
As I said earlier, I had the 36vm kit from Rocky point but that was with a stock cam and a detuned Combat head and stock exhaust. After adding many performance upgrades, the vm just could not feed the beast enough to make it go.
My decision to go with this TM40-6 was not a willy nilly thought. There were 2 major thoughts that brought me to the experiment.
1. The Tm40-6 was part of an "Easy Kit" for the Harley 883 which I believe proved to be too small and they went up to the 44, 46 and 48.
2. The second thought was that CNW was using 2 35mm pumpers. It they have success with 2 35, the one 40 can't be far off.
As with the twin 35 FCR's, you have to be a little carefull when starting cold, starting hot and blipping the throttle at stop lights or just idling in the yard. It's easy to soot up the plugs with bad habits.
Starting cold I turn on the gas, give it a good pass through, then turn the key and fire it up. When warm, be vary careful not to overwork the throttle.
