Technical IMB3 Carb

[jolly500]

Hi.

I have found an good IMB3 carb amongst my spares. I believe they were fitted to the 500 Sport?
Would there be any benefit fitting the carb alone to a 'D' engine, or would it need camshaft etc changes as well?
And if so, any idea of the spec for the Sport camshaft?

Thanks
Steve

 

[smart51]

The Sport had 3 differences with other 500cc engines, the cam, the carb and higher compression.

The F/L had the same cam as the sport where the D and N shared the same cam. The F/L had 18 BHP and the D 17.5 so the cam is only worth 0.5 BHP. By my estimation, the extra compression of the sport gave it 1 extra BHP. That leaves the sport with 2 BHP more than the D and by deduction, that must be down to the carb.

The IMB3 carb will flow more air than a standard 26 IMB but not as much as a 28 IMB. Fit it by all means; get yourself a bit more power. There are other ways to get two extra horses, but few are as easy as swapping out the carburettor.