Thundercat FCR Jet sizes

[Kensei]

I've just installed a set of 35mm flatslides on my thudercat engine (standard engine).
I'm racing on saturday so don't have time to put the bike on a dyno.
Can anyone give me a rough idea of the right jet sizes to put in the carbs for this engine.
I'll get it dyno'd shortly after the meeting but i'd like to be in the ballpark.
Thanks

[oldbelly]

Our Thundercats always ran 33mm carbs, we used 35mm carbs on the R6s. A 118/120 jet would be right for a Thundercat on 33mm carbs and the R6 motors were anywhere between 135/140jets. Try a 130 and do some plug chops Ken.

[gatekeeper]

i ran 118/122

[powerhouse]

Thundercats run better on 33mm carbs as they can suffer from fuel dropout at low intake speeds, best to run with what you had ken, least you won't run it lean.

[lang]

I spent a long time in 1996, carburation testing on thudercats, using the same engine on the same dyno on the same day the best results i obtained using 33 fcr, 112 bhp,49 ft lb torque. Using 35 fcr, 108 bhp, 44 ft lb torque. The settings for the 33fcr were 118 main jet, 90f needle, 2.0 float valve, std blue bellmouth. Did not use the 35 fcr as the power loss was to great.

[lovingit]

totally agree with the other guys 35mm no use on t /cat youll end up with less horsepower

[Kensei]

Thanks for the advice guys.

I'll have to struggle on with the 35s for the minute. The 33's i had were non functioning in more ways than one, and the 35s were the only ones I could find at the time and at the right price.

I'll be moving to fuel injection later this season/ early next so it's just a stop gap. Got 6 weeks till i'm racing again potentially so i'll get it on the dyno and do what I can.

[stepawley]

we run 118 up to 122 ste pawley

[Kensei]

Thanks, I've got 118s and 122s. Seems to be working fine so far, it'll do me untill I get a fuel injected motor later this year.