Carbs

[Chino886]

Can you have a carb that is too big?

[bwamos]

Yes.

If the carb is too big, you won't get enough velocity through it and won't have enough vaccume across the jet to allow it to pull fuel through efficently.

Besides you want velocity so your cylinder continues to fill even when there's no more suction coming from the down stroke.

That's why the proper size carb and porting is important. Bigger isn't better once you pass the optimum size for your target rpm.

If you want more torque.. you want a smaller carp and porting for more velocity at lower rpms. If you want more top end hp, you go with a larger carb and ports for less restriction at high rpms.

But a 48mm carb on a 300ex would never be optimum unless you were running at like 18,000 rpms. ;)

[Chino886]

Originally posted by bwamos
Yes.

If the carb is too big, you won't get enough velocity through it and won't have enough vaccume across the jet to allow it to pull fuel through efficently.

Besides you want velocity so your cylinder continues to fill even when there's no more suction coming from the down stroke.

That's why the proper size carb and porting is important. Bigger isn't better once you pass the optimum size for your target rpm.

If you want more torque.. you want a smaller carp and porting for more velocity at lower rpms. If you want more top end hp, you go with a larger carb and ports for less restriction at high rpms.

But a 48mm carb on a 300ex would never be optimum unless you were running at like 18,000 rpms. ;)

so do you think that a carb set up for a 440 would be too big for a 400, i already have a port and valve job.