RB inlet

[jason frost]

So this is how it ended up

standard



welded up


opened up to match the reed but I not like the bridge so


Took it out

[rossi46]

Looks like mine !!!!

[Knowledge]

I don't like the RB inlet. The cross sectional area increases too much as it approaches the reed cage. Masking a considerable part of the reed with the standard manifold is odd, but could be deliberate.

A radical approach to the manifold would be to have a special inlet manifold, feed by 2 x 24mm carbs: one on each side of the engine. If you do the maths, the cross-sectional area of 2 x 24mm carbs = 1 x 34mm carb. Improved bottom end response from a smaller carb would be a benefit.

Too radical?

[corrado]

[quote="jason frost"]So this is how it ended up



You missed a bit....

[sean brady scooters]

two carbs which may be smaller,yet give the same area as a single big carb............will of course only get half the suction each.............
this will affect inlet charge velocity .......
a single carb will always be superior ...............

[bootros]

Using simple numbers:

If the single large carb has an inlet area of 10cm2 and the two small carbs have an inlet area of 5cm2 each then the velocity in each is the following if used on a 200cc motor:

Large carb: Velocity = volume per second / cross sectional area = 200 / 10 = 20m/s
Small carb: Velocity = volume per second / cross sectional area = 100 / 5 = 20m/s

This assumes each small carb shares the volume flow rate equally.

[jason frost]

You missed a bit....