Hitchcocks Forum

Getting my 612 crank order ready but unsure if I should get bigger jets , I'm building my 612 engine the slow way and the last bits need adding .
I'm gonna take the plunge on the race valve set(90052) and with all that extra space too rush by more should get in but... a thinner mix with fuel/air ?
32mm at the intake joint still , will it be lean or the same ?

I think I'd speak to Hitchcock's for some guidance. They must have more experience of the 612 than anyone else, and I'm sure that they'd be happy to advise you.

i am in the same position getting parts together, but i want a soft torquey engine i will be going up to are hosts in a couple of weeks to get the 612 crank ,barrel and piston and associated parts. as you i have a 32mm amal carb and want to know jetting etc this is the main resin to visit the shop
john.

I'm using a Amal concentric MK2 which is bigger and better than the MK1 , I had to saw off 1 petrol tank fixing lug and cut back the lug on the frame and it's still a tight fit with the cable , I think the jets for it are 240 main 25 pilot and nuber 3 slide , choke dont work so I cap the air filter for 1 kick to wet the plug of which I now have 2 .The rubber tube stopps heat transfer and the manifold could do with a left hand curve as per Fury head .

Hi Phil, why doesn't the choke work?

I dont know why the choke does not work , I start the engine using a foam air filter cup and wet the plug with a induction kick through with a touch of throttle then a real kick start and the engine bursts into life , if I apply the choke at this point the engine cuts out , I have a leftie lever thats hard to get to but it will never wet the plug . I live in Australia so it's never really cold so really no need for choke , the carb is a Amal concentric MK2 which is a joy as the slide never rattles never jams and is heat proofed by the rubber induction tube , I have the extended mixture screw so I can tweek the mix with my fingers for cold day starting .