Main jets for KZ750B, will these work??

I stumbled across this site that sells mikuni main jets and I found these. these look like I remember the mains from my 750b look like but its been awhile. Can anyone tell me if they are the right ones?? The web site is www.allensperformance.co.uk/mikjets.html

Wow..... those do look like the ones in my KZ 750 B4 that go in the Mikuni BS-38 carburetors, hard to know for sure from a photo because you can't gauge size exactly. If you have found a source for them, that is basically the holy grail of old twin carburetors.:laugh:

The only other place I ever saw them was in the Keyster rebuild kits that supply the stock 125 main for the carbs. Never saw a source for any other size.

Keep us posted, you may have struck gold.


If you find a place that stocks the 32 mm valve shims I will personally see you are given sainthood.

They may work... measurements seem to be the same.

The description says:

4.0mm Slot head

6.5mm Length

3.00mm Thread length

That would mean the diameter is about 0.16" and length is about 0.26" if my math is right. I have my extra main jets right here and the measurements are:

diameter = 0.165"

length = 0.258"

They look like the right size if the given dimensions are accurate.

I could be wrong. Buy some and check. I don't know of another bike that used the small main jets that are screwed into the bowls like the KZ750.

Looks like there is only one way to find out. Anyone know what the stock jet size is?? I wanna get one size bigger and I'll just try ordering them from here and find out.

Stock main jet is 125

steell wrote:

Stock main jet is 125

Yep, and I still have the 130's that made the engine scream with the old Kerker clone header. If you are going to screw with pipes or air box you will need to go larger.

BTW, the stock pilot jets were 45 for everybody but the poor fools in california who got 40's that ran like crap.... mine always ran best with 50's. If your pilot jets are buggered, they are available at many places: Mikuni BS30-96, you can get size 40 - 60.

awesome, thanks guys. I'll try this out and let you know.