I have no idea what size of carburetor is appropriate for an engine of this size. Any helpful pointers will be most welcome!!

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I have no idea what size of carburetor is appropriate for an engine of this size. Any helpful pointers will be most welcome!!

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I found this on the internet - may be of some help .

There are plenty of engine cfm calculators out there also .

https://www.rcuniverse.com/forum/engine-conversions-92/839599-formula-calculating-carb-size.html

Also this app for android ( free )

https://play.google.com/store/apps/details?id=cal.size.carburator&hl=en_AU

There are plenty of engine cfm calculators out there also .

https://www.rcuniverse.com/forum/engine-conversions-92/839599-formula-calculating-carb-size.html

Also this app for android ( free )

https://play.google.com/store/apps/details?id=cal.size.carburator&hl=en_AU

Last edited:

Traxxas Pro 15 carburetor works well on Webster.

Brian, I seem to recall seeing a post where you tried Chuck's carb on your Webster, with success. Do you recall which version (which throat diameter) you used?

XD351, very interesting formula. (And an app - I never would have thought to look for such!) I tried out the formula, and realized that RPM is a dominating variable with an engine this small.

.875" bore x 1.25" stroke = 12.32 cc, rounded to 2 decimal places, if I have done the math right.

Here is the chart, showing the lower and upper ranges (K = .65, K = .9) at assumed RPMs of 1000, 2000, 3000; results are in inches of diameter:

In the two variations that I've seen for Chuck's carb, the throat is either 1/8 = .125" or 5/32 = .156". Looks like .125 would be more appropriate if the RPM tops out at 1,000; .156" might be ideal for a top RPM of 2,000 to as much as 3,000.

So ... for an engine like the Webster, what is an appropriate upper limit for the RPM? For that matter, what is a typical RPM at idle?