First Generation Ascots > Tech Section
Dyno tuning
scottly:
After swapping the #25 pilot in, the hesitation was even worse! At 1/8 throttle, the bike ran poorly, even in neutral, and the spark plug was sooty. I happen to have a VM 32 on hand, and comparing the two carbs I found there was a brass washer missing on the VM 36 between the main jet and the emulsion tube/needle-jet/main jet holder, which may have allowed for fuel to leak past the tube. Sorry, no pics of the washer, as it's now on the carb on the bike, but I've pointed out the shoulder where the OD of the washer would seat, drawing the tube firmly down.
scottly:
With the missing washer replaced, the bike ran much better, enough to ride it to a bike show last Saturday. ;D
Yesterday I ran it on the dyno with the #25 pilot, and found it to be lean compared to the #35, but the tests with the #35 may have been skewed by the missing washer.
I made 3 runs back-to-back; the differences at the right side of the graphs are due to the rate of opening the throttle. Run 189 in blue was with the throttle opened somewhat rapidly, run 190 in red was with the throttle gradually rolled on, and run 191 in green was with the throttle snapped open as fast as I could. The motor bogged, then recovered, which is why both the HP and torque curves on that run start above zero; it confuses the dyno computer.
scottly:
Pulled the carb off the bike today to replace the original #35 pilot. In the 2nd pic, with the jet removed, you can see a gap between the bottom of the washer and the tube, which simply dropped from gravity. I suspect that when I took the carb apart last summer to check the settings the washer fell out and I never noticed it.
scottly:
I tested my new pipe today. :) :) The graph shows the new pipe compared with the best previous run:
J6G1Z:
Congratulations you passed the 30HP level. 8) This illustrates how much a free flowing exhaust can release more power.
Have you noticed any change in MPG, or range on one tank of fuel?
Please keep up the good work & documentation.
J.
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