atc90 stroker carby help

[vroomy]

hi, finally got my atc90 motor back from a fresh build. Its running a Helm&Son stroker crank with 54mm piston which should be around 133cc? anyhow im trying to figure out what size carb i should run? i have a 26mm mukuni and a 21mm keihin copy any of those work well? i was going to run the 26mm but it wont fit my sudco manifold, the bolt holes on the mikuni are slightly offset. Can anyone here give me some advice? cheers

[shortline10]

26mm is a little to big IMO , it will work but throttle response will be boggy , 21mm might be fine but I’m not a fan of China carburetors .
A genuine VM22mm or VM24mm mikuni round slide is you best bet or a old school 24mm Keihin if you can find one .

[vroomy]

Ok ill start looking. Any idea what manifold fits these larger carbs properly?

[DAM shop]

Ok ill start looking. Any idea what manifold fits these larger carbs properly?

I believe the bolt width on a 26 is a bit wider than a 22 but I could be wrong. I've never had an issue with my 22's on any of the four aftermarket intakes I have.
And make sure you are getting a genuine mikuni, there are plenty of copies ones on the market.

[Joseph Farrow]

I agree with Mike. A 26mm is almost too big for even a 180 motor. The VM22 would make your 90 scream. Will be a lot more responsive than anything larger.
At 133cc and 54mm Bore you should have a 58mm Stroke. Good running little set up.