Looking to ID who did the work on this cylinder

[91 KDX 250]

I just acquired a 1991 KDX250 (joy ) and it appears to have been worked on.
Still have not checked the carb for the usual mods, but the cylinder has engraved initials on it.
Looks like a =KB except the top line is longer than the middle one. Hard to explain.

I'll try to grab a picture later tonight and check the carb for the mods.
Does have a Pro circuit pipe with stock silencer.

Seems it was modified quite a while ago.
Any other goodies I should look for?

[KDXGarage]

Welcome to kdxrider. Post a pic. What country are you and the bike from????

[ohgood]

Ron Black?

[91 KDX 250]

Hey all, thank you.
From the USA.

Here is a picture. There are 3 "speedy" lines in front lol

[KDXGarage]

Thanks.
Maybe someone will know.

[91 KDX 250]

There we go. Had to include link to full size image, for whatever reason it was linking to the thumbnail.

Will have a check today to see what the carb has in it

[david]

There is a KB Motorsports in KY. Don't know how long they have been in business or if they used to do custom cylinder work, but you could give them a call.

[91 KDX 250]

Thanks.

Doesn't look like anything special was done to the cylinder or head except it was sleeved.
Was pretty worn out lol. cylinder measured at 67.9577mm and piston at 67.3633mm.
Just over half a millimeter of side wall clearance!

It's not oval, nor does it have any scarring, so I Might try to hone it out to size a 68mm piston but don't have actual measurement specs of the 68mm wiseco piston # 607M06800

Has anyone mic'd a 68mm piston? Would hate to waste $100+ if the 68mm pistons mic out smaller.

Other than that, it looks like I might have to get it bored to 68.5.
Can y'all suggest reputable shops that don't bore out on the high clearance side of things.(hate when they do that)

Thanks!