Main Motorcycle: 07 Bonneville
Join Date: Sep 2007
Location: Bonnie Scotland
Other Motorcycle: another 07 Bonneville
|Air Cooled Twins Technical Talk Technical Talk for Hinckley Triumph Twins: Bonneville, Bobber, T100, Speedmaster, America, Thruxton, and Scrambler.
Sponsored by: Triumph Twin Power Ltd
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Thanks for your input guys. I agree, float height, slide and needle are all important (I haven't discovered what float height does to fuelling throughout the rev range/ throttle opening range though, so comments welcome). What I found interesting was the differential between pilot mixture screw adjustment and pilot jet size.
On this forum, it's common to hear everyone talk about 'how many turns out on the pilots screws' etc, then others talking about setting the screws for best idle. What I found was that setting the screws for best idle doesn't necessarily mean you're setting for best low-throttle cruise fuelling. You can't really tell (unless you're very experienced) what the fuelling is doing at cruising speeds after you alter the mixture screws and/or pilot jets, unless you have an a/f gauge or a dyno measure at that throttle opening.
We go to a lot of trouble and expense having our bike's dyno'd for main jet size, maximum power and at wide open throttle. However, where we do most of our riding isn't at WOT or even 50% throttle, it's down the lower end of the throttle opening, with intermittent, short bursts into 50 and 100% throttle (acceleration and overtaking etc) for normal road riding. So it follows, in my thinking at least, that also paying close attention to fuelling at up to 25% throttle would be pretty crucial for overall best performance, since you could be running very lean for most of your riding (as I was) when your 100% throttle dyno curve says otherwise.
Others who are more experienced may disagree, of course, and if I'm wrong it'd be good to hear other views.
All the best.
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