Hitchcocks Forum

Hi folks

Just finished rebuilding my Bullet 500. Have put in competition cam shafts and high compression piston. Modifyed the top just a little by opening both inlet and outlet side.

I have kept the Micarb, no air filter just a bellmouth With gauze. My question now is if anyone can guide me too which jet setting would fit. The bike gets far to much air and I had to Block most of the bellmouth inlet With tape to make it run at all.
I know Our host have jets of different sizes but I don't know which jet combination to choose.

Terje

Heres a good guide from our hosts.

Go rich and work back to correct mixture.. NEVER too lean or you'll be needing a new piston before you know it..

I know of one tuned 500 with a Mikarb that needed a P4 needle jet. A.

With that kit why not put on the 32mm Amal mk 1 as recommended by our hosts?

Check the manifold flange and rubber for any splits cracks or source of air leaks.


You have a major one...

Did you think to improve the bottom end with decent mains and big end?
If not you may be rebuilding again pretty soon.

Hi

Thank's a lot for answering.

PeteF; yes I hav done the bottom end. New roller bearing big end and all new bearing. Also gear Box lots of new parts.

Gwilly; thank's for the guidance. I think I'll order the biggest and secon biggest jets and try from big to smaller.

I'll post som pic's soon if you are interrested and if I'm able to figure out how. The bike has got totally changed and I think it looks good.

If anyone else have more info concerning jetting I would be happy to hear Your experiance.

Terje

The main jet only really begins to have any effect on mixture over 4500 rpm -> full throttle...


misfire on acceleration is LEAN (Needle jet and then main jet)


having to 'choke' the bell mouth is LEAN (Air leak at manifold)


spitting back on opening the throttle is LEAN (Throttle slide)


erratic idle and a slow return to idle is LEAN (pilot jet and or float level and air leak)


Incorrect valve timing (inlet over advanced) will exasperate 'spitting' back.


Float-level and fuel flow capability through the tap both effect overall mixture.


You have a Hot-rod 500, most probably fitted with a fuel tap that was sized for a lowly tuned 350?

Micarb is a crib of the VM carb, so go to http://www.mikuni.com/pdf/vmmanual.pdf for all the gen for setting it up.
No doubt Mr H will be able to provide jets etc as needed.

Oh, and of course, once you have a spare or two.... a too small jet can always be made bigger; (it's the size of the hole that matters, not the number stamped on the side!)
I have even "tinned" jet with solder to reduce when dealing with obsolete ones.
Sewing needles come in various sizes and I've found them useful in grading hole sizes... this is true Indian engineering!!