Hi Keith,
Short answer:
I took my Speedy to BIM in Vancouver to ask the same question. They didn't think that changing to K&N and / or the belmouth would make much difference at all.
Long answer:
However, seeing as I was getting a dent in my tank fixed, had just got my stock pipes back from Chevy605, had picked up some Thruxton needles plus needed to send the bike in for a service anyway I asked them to rejet while it was there.
I bought the bike last September, it was 4 years old with 2200km on it so they also suggested stripping and cleaning the carbs too as the tank was off anyway for a week while it was getting pulled and painted.
When I got it back they had set it up with the stock main and pilot jets (120/42) back in there but installed the Thruxton needles with 1 shim (I never asked about shim thickness or how many turns out)
I thought the combination of pipes, filter and belmouth would mean re-jetting for sure but it appears not when taking the needles and shim into account. When I entered my config in to Pats jetting calculator it actually suggested the exact same setup as they gave me. 120/42/Thruxton/1 shim. That's the same result the calculator gives without entering any option for having a belmouth or not.
That was 4 months ago now and I've put 2000km on it and it's running great. Even get an extra 25km out of a tank round the city before I have to switch to reserve.
The point of my post is that the dealer set it up exactly how Pat's calc suggested (maybe they use it too) which makes me trust its suggestions and they were confident the K&N + belmouth over the stock filter and snorkel wouldn't make much of a difference to A/F mixture
Last edited by dogshrimper; 03/18/2010 7:10 PM.
