Hitchcocks Forum

Hello All
I’ve been assembling various bits ‘n pieces to make a Bulsader (535 Bullet engine in a Crusader frame). The head has been ported to match a 32mm Mikuni, and it breathes through a large conical filter and exhausts via a fairly free-flow silencer. Everything else is standard.
This afternoon I attempted to start it for the first time, and it ran (sort of...)!
In order to make it run even a little I had to wind out the idle mixture screw 3.5 turns, so the idle jet is obviously too large. It’s marked 3.25. Even with this I had to keep blipping the throttle to prevent it stalling.
Question is, what would be a good starting point for the idle jet? I believe the Mikuni and Mikcarb share the same jet system and size designations...
Thanks

for a standard bullet with open filter and exhaust and standard cams a 32.5 is good.

as the stationary circuit is better performing than the original micarb you should be able to run it on at 30.0 in some occasions even a 27.5.

be aware that a mikuni will not be able to start a cold engine without the choke!

as a main jet a 150 should be a good starting point, needle halfway.

Thanks Mauri, I’ll give it a go!

Our hosts have a useful jetting guide here -

https://accessories.hitchcocksmotorcycl ... ttor-parts

Hello, yes I had a look at H’s guide; not sure how to extrapolate for 535cc capacity and 32mm carb...?
S

If you can get your paws on a Gunsons Colortune plug you can SEE the color of the combustion, and dial the mixture in to perfection. I use mine mostly on my 74 Trident as it is difficult to hear the differences while adjusting the airscrew..