Mikuni smoothbores

The Mikunis on my Rickman Kawasaki have been sticking,especially after being parked for awhile.During the racing season even with frequent use they are slow to close.I put a stronger return spring on to get thru the season.I have the slides out on the bench and can see faint scuff marks on the chrome at the top third of a couple of the slides.Can I gently sand them with 2000 grit or maybe rubbing compound or would it be better to try and smooth the interior of the carb bores?Or ???
Jerry

I just rebuild mine. Inside the carb there is a peice called jet block. If you install and its misaligned the slide will rub against the carb

I'm assuming you have smooth bores.
What speedy gonzalez said. The jet block has to be centered in the carb body or the slide will hang on them. You may have cracked jet blocks causing misalignment, I've seen that make slides stick before.

I've not familiar with that.Is that the round casting/guide at the bottom of the carb bore?Is it adjustable? Is there good detailed info out there to set up/rebuild these carbs.
Thanks.Jerry.

www.jetsrus.com/photos/photo_mikuni_VM29_exploded_view.JPG

#87 in that view. you can overtighten the small screw that holds it into the cab body and possibly get it out of alignment.

Yes 29mm smoothbores.

Thanks guys.I'll let you know what I find now that I know what to look for.
Jerry

Next time you have them off, take the return spring off, then raise the slides like you are opening the carbs up ful throttle. They should slide smooth with no sticking. If they stick, pull the slides and jet blocks out one at a time to find the ones that are sticking. Don't overtighten the small screws in the bottom of the carb in the bowl area.
Do you know if they are early smooth bores? These had a problem with the shoulders cracking and misalignment.

The earliest 29s did not have the bowl plugs in the fuel bowls. That doesn't mean that the bowls weren't replaced at some point in time though.

I checked the jet blocks and they seem OK,no cracks.I polished the slides with 2000 grit paper and WD40 and reinstalled them on the bike last night.They seem much better now.
Thanks to everyone for the info.
Jerry.

The throttle assembly is original(old-like the rider).I'd like to change it to something more modern.I'd like a more sensitive throttle,it's hard to get from zero to full throttle,too much rotation for antique wrists.I need a push/pull throttle and I'm computer lame.I did some searches but didn't have much luck.Any suggestions?
Jerry

jerry a smith wrote: The throttle assembly is original(old-like the rider).I'd like to change it to something more modern.I'd like a more sensitive throttle,it's hard to get from zero to full throttle,too much rotation for antique wrists.I need a push/pull throttle and I'm computer lame.I did some searches but didn't have much luck.Any suggestions?
Jerry

From a different forum--
Quick throttle
Put a Honda CRF throttle tube on the Frankenbike, like I've done with my Z1000's, AWESOME. I had forgotten what a huge improvement it made in throttle response. Makes the bike feel like it has way more HP. Of course it doesn't, just the power comes on a lot faster.

Usually I just buy them from Honda, but this one I got off another member here, it's a Motion Pro throttle sleeve for a Honda, part no. 01-0097.
You take the old one out, sand some material off the one side of the new one where the cables go, install the new throttle sleeve, cut some plastic off of the 90 degree elbow, and done
Trim the pull cable plastic 90 degree piece about 1/4" where it rubs the throttle tube. I do it with cutters...it's not critical.

Lube everything with light grease.
I run the CRF grips...I tried every brand of MX grips I could find and the Honda ones I loved the best. Plus, they fit the throttle ridge and that means the grip does not get wedged between your thumb and the switch housing and the throttle works smooooooooth.

You have to remove the grip and re-locate it in the correct position because the CRF cables come it from the top. And, the grips are CHEAP! One comes with the throttle tube free from Honda.