main jet internal diameters
 

Hi

I am wanting to up jet and read in a post about reaming the original.

I have a good set of very fine drills but does anyone know of a cross reference for main jet size and the diameter of the hole? I'm looking to start aiming for a 105 and maybe move up from there.
Anyone any thoughts?

Cheers

Frog

If you have a dial caliper. You can find a drill that is 1.05. Thats also how You can do it with the tip cleaners.

Yes acetylene torch tip files are cheap and come usually with a tip cleaner/ hole diameter chart stamped in the lid... :wink:

Also for interests sake you could google a conversion chart for machinists that cross reference hole size mm/inch fractions/thousands and letter size drill bits.

Ok , here ...
http://www.engineersedge.com/drill_sizes.htm
Handy hole chart. and good place to look around...at least for me :roll:

Be careful, not all Main Jet Sizes Correspond with Drill Sizes!!!

So what would they corespond with if not mm? All may not be measured in mm but all I have seen are.

If you look at a #115 jet from a Mikuni verses a Keihin carburetor the sizes are not the same at all... there is a big difference. So no, not all jet sizes correspond with drill sizes.

I stand corrected. Mikuni does use a different indexing number. However on these bikes and most others I have built the mm does match up. Here is the screwed up way Mikuni gets thier numbers.


http://www.ozebook.com/compendium/t500_files/mikuni.pdf

Thanks everyone - I'll let you know how I get on!

regards

Frog :D

I am the one who used the torch tip cleaners to ream my main out. I found the cleaner (file) that just fit into the jet and reamed the next size up, then the next size after that. The torch tip cleaners work well, but it's a slow process and a painful one on the fingers. I would try the files before the drill. It's not hard to mess up drilling something so small and your margin of error isn't very big. When I reamed out my main you couldn't even tell I had done anything by looking at the hole, but it made a BIG difference in the way it ran.

Red any chance you could put a dial caliper on the cleaner you used? Inthese jets they will measure in mm. Or it could be coincidence.