Hitchcocks Forum

Hi. I'm wanting to upgrade to a monobloc carburettor for my 1951 350cc Bullet, getting fed up with the current carb flooding etc. Which size of monobloc do you reccomend? Thanks

15/16"

Thanks Tim
375 or 376, and what size jets?

Hi whats wrong with a nice 30mm mikuni about 100 main and 25 or 27.5 pilot even years ago thought amals were abit over rated. Still have the original carby miku I on a 81 suzi bout 70000 on the clock and no sign of wear. If all thebrit sgtuff was so good how come they went bust.

30 mill is a bit big for a 350, as Tim says, around the 7/8 to 1" range would be about right.

Just cross referenced Amal listing with Roy Bacons listings and it seems Amal 376/029 @ 1" bore was used on 57-61 clipper, 55-57 G2 Bullet, and 60-61 bullet.

All used same jetting as follows....

Main Jet 180

Pilot Jet 30

Slide no 4

Needle Jet 0.106- 0.11

Needle clip position 3

A starting point anyhow. cheers gwilly..

The '51 has a weaker bottom-end than post '55 motors, and does not want or need a large bore (revvy) carb.
376, Std AMAl 4 stroke settings: 25 pilot, 3 1/2 slide, 106 needle, clip in mid pos, 160 main jet Main jet; it is probably going to be too rich, but then again you may never really find out. I would not rev an old narrow-rod motor to the point I could accurately set the main jet.

51 Bullet should have a 1" 276 with a long throat. The model G had a 15/16" I believe.

Thanks for all the contributions.
A 30mm carb is a tad excessive as the inlet manifold is 15/16" (24mm) apart from the carb looking totally out of place on a '51 machine.
There are a number of 376's that will suit but another issue I didn't consider before is that a monobloc carb will not clear the magdyno so I will also need a spacer for the manifold.
Any ideas?

Just seen the 3/4 spacer on our hosts listing, that may suit. Off to the garage to measure up.