77 KZ750 twin help needed with jets...

....Well,I have been tinkering with this bike for days,thinking I had a points/ignition/plug problem.

Turns out one of the main jets is butchered!

So...The bike has a fresh rebuild,pods,and a 2 to 1 exhaust...Instead of getting just one jet,I should probably just get the right set..

What am I looking for,and will my local shop have what I need?

Pretty sure the carbs are Mikuni BS-38's


Thanks in advance!

Main jet size is 125 stock, might give Z1 Enterprises a call and see if they can get them.

Her's a link for a discussion in Ibsens twins group> www.armbell.com/forum/viewtopic.php?t=4374&mforum=kz400

About 3 replies down, one of the members say's what jetting works, for a friends '76, w/BS38's, running pods.

steell wrote:

Main jet size is 125 stock, might give Z1 Enterprises a call and see if they can get them.

They can't, and neither can anybody else. I already went through all that. I found the stock main jets are only available in the Keyster rebuild kits.

www.loudfastugly.com/carbkits/carbkits.htm

I'll wager the stock jets won't run worth crap with pods.

have you tried motorcyclecarbs.com ?

ronjones wrote:

have you tried motorcyclecarbs.com ?

Yes, they don't sell them. The Mikuni BS 38 uses a tiny main jet barely big enough to drill the hole in. I have never heard of any place selling them anymore.

Thanks for the info...

Not our normal source for parts, but you can check Mikes XS for Yamaha 650's. The 70 - 79 XS650's used BS38s. I have two Yamahas I'm currently working on.

Part # xs 48-0659 for the needle
xs 48-0210 for the 125 jet


They do have jet sizes from 115 to 160 listed.

my catalog is a couple of years out of date so I don't know if the pricing is up to date.

Good luck!

And I think I may have an extra stock air box for the 750 twin laying around here if you can't get it to run right with pods.

Sixgun wrote:

Not our normal source for parts, but you can check Mikes XS for Yamaha 650's. The 70 - 79 XS650's used BS38s. I have two Yamahas I'm currently working on.

Part # xs 48-0659 for the needle
xs 48-0210 for the 125 jet


They do have jet sizes from 115 to 160 listed.

my catalog is a couple of years out of date so I don't know if the pricing is up to date.

Good luck!

Let us know if those are the right main jets for the BS 38's. Sure would be nice if they were. I checked babbitt'sonline.com for the OEM part numbres they show and they are different. For the Kawi BS-38 on a KZ-750, the stock 125 main jet is 92063-143. They list the 125 main jet for a 1976 YamahaXS650 as 3G2-14231-25-00.

There's a pair of carbs for a '79 on ebay. I believe they are BS38's.
tinyurl.com/43mjlv

I believe those are Mikes XS numbers. I have his paper catalog and all his par numbers follow that same pattern. Here's his number 352-540-9204. He might know if they're a match.

I bought an extra set off of ebay for my 750. The jets weren't in the best condition, but it was the floats I was after. It's worth a shot if the price is right. I think I paid $15 for my set.