Mikuni BS/CV and VM O-ring Kits

[Nessism]

Hi Ed. I notice above you said you don't have a kit for the KZ550. I recently picked up a 1981 KZ550A with the TK 22mm VM carbs on it. The bike has sat for years. I haven't done anything to it yet other than check compression.

If I sent the carbs to you and paid return shipping costs, would you be willing to create an o-ring kit for them?

We can disccuss further via DM if you'd prefer.

Rock ON! I'm your guy! Please send a PM so we can discuss.

I rebuilt a set of those carbs a couple years back, and (sadly) can't remember the specifics, regarding O-rings and such.

What I do remember, is that the choke flaps come loose on those carbs, so some extra measures are required, or the mechanism can break loose, and get ingested by the engine.

There used to be a super cool, and knowledgeable dude on KZ Rider, who was an electrical and 550 expert. Sadly, he passed away. A massive loss to the community. I have no clue who is paying his old web hosting fees, but his old pages are still accessible. I strongly suggest you download all the content you can from these pages, before they go away...

https://s3.amazonaws.com/gpzweb/index.html#home

[Griffin]

Thanks for the link, Ed. Lots of good information there.

I'll PM you after Christmas to discuss details.

[Nessism]

Feeler post...

I've been doing choke plunger rubber seal replacement for a few years now. I do these on carb rebuild projects, where the client wants a fully "restored" set of carbs. For normal "rebuilt" carbs, I don't do this. The original plungers are used as is, and in most cases, they work well enough, even though the seals may be deteriorated.

I made some tools, to punch out the seal donuts from Viton 2mm thick rubber sheet. The exact size was just a guess, though. More recently, I cut apart both a VM and BS/CV plunger, in order to better understand the size of the plunger "cavity", where the seal resides. What I learned is that the VM carbs need a 7.0mm diameter rubber donut, and BS/CV carbs need 7.1mm.

The seals I had been making before, were larger than that, which made installing them into the plungers difficult.

I've now come up with a process to make the seals an exact fit size. This makes install much easier.

I'm considering offering the seals for sale for customer install, or offering an "exchange" service; send me your plungers, and assuming they are in rebuildable condition, I'll send refurbished plungers back to you.

Does this sound like something anyone here would be interested in? If so, please respond, or send me a PM.

BTW, member Zed, offers a choke plunger rebuild service currently, and I don't want to insult his great service and work. Being that I'm already providing O-rings, this seems like a logical add-on, though. Be your own judge.

[Wallowgreen]

Without the special tools you made for the job, how difficult would it be to pull out the originals?

What about installing the new, simple press in by hand?

Could be a simple add on for me, especially with bikes I intend to keep so I'm interested.

[zed1015]

Without the special tools you made for the job, how difficult would it be to pull out the originals?

What about installing the new, simple press in by hand?

Could be a simple add on for me, especially with bikes I intend to keep so I'm interested.

Depending on the condition of the old seals it can be very tricky and time consuming getting them out as many times they can be as hard as plastic so won't simply pull out and unless the seals are undersize or the incorrect shore rating ( i.e too soft ) it is impossible to reliably fit new seals by hand without either damaging the seal or the original rolled brass securing edge.

[Nessism]

Without the special tools you made for the job, how difficult would it be to pull out the originals?

What about installing the new, simple press in by hand?

Could be a simple add on for me, especially with bikes I intend to keep so I'm interested.

An overnight soak in carb dip, will cause the seal to greatly soften and pooch out. A pick tool can then easily remove the seal. A torch can also be used, but this requires more care.

To install, first coat the seal with silicone grease or similar. Push the donut down over the plunger peg, and tilt it up, so you can tuck it into the plunger cavity on one edge. Push the seal down, working it under the lip on the plunger. Using your fingernails, work around the plunger and push the donut into the cavity, to the extent possible. You can usually get about 3/4's of the seal past the lip, using your fingernails. Then, I use an old pick tool that I reformed into a spoon shape, and a small screwdriver, and work the seal into the plunger. The Viton is tough, and doesn't tear easily. Just be careful to not press with any sharp edges.