TOPIC:

Hi All

It seems my pilot circuit is bunged up. After a blissful first couple of runs, the bike now runs rough at idle. Adjusting the #2 idle screw does not affect RPM like the others, If i turn it all the way in, the idle does not drop, so it is probably plugged.

I am becoming convinced I did not clean the pilot passages properly the last time they were off the bike.

I have seen a good process for the "air screw" VM26 type carbs; where it states things like "block here and here, force carb cleaner through here....etc"

Is there a similar drawing / process for my carbs available? 1977 KZ1000, VM 26 with the pilot screw on the bottom.

Thanks!
Chris

Same procedure except those are fuel metering not air. What do your plugs look like? pics?
Steve

Hi Steve

Here is the procedure for the air screw carbs








And here is my carb


Some of the things the procedure tells me to do cannot be done due to the differences.

Wondering if a similar "block this...spray here" procedure drafted up for my specific carbs.. If not i think i can figure it out but would realy like to follow a proven process.


Have not bothered to pull plugs yet, need to get the #2 pilot to adjust properly (like 1,3, and 4) before I get into that.

The plugs tell you a lot of what is happening, rich or lean.
Steve

My number 2 pilot passage is blocked.
When I fire her up and let it idly the #2 pipe doesn't get hot, if I throttle it and bring up the R's the pipe heats up quick.
All my plugs are a lovely light brown.
JD

Clogged pilot.
Steve

Went through the carbs last night and made up a procedure for these specific carbs. Hope it helps someone down the line. When I did this last year I did not appreciate that the pilot paths need to be specifically, carefully cleaned.



If anyone sees a flaw here please pipe in. I can edit as necessary.

Cheers
Chris

The pilots are very small. I use a guitar string or a wire from a brush to clear them.
Steve

Best way to clean carbs is to ungang them and soak the body and parts in carb dip. This will deep clean all the various internal passages and unplug jets that are varnished closed. It's always best to verify the passages are open by spraying carb cleaner through the various passages after the dip session, but this is a confirmation test, not the actual cleaning procedure.

cycleorings.com sells O-ring kits for the VM series Mikuni carbs. Carb kits should be avoided since the brass parts are typically of inferior quality to that of the original Japanese Mikuni parts. Sometimes they are unavoidable though.

It is a rare occasion to have to fully disassemble the carb rack. If they are that bad, I would just replace them. Most of the time they can be cleaned as a unit.
IMO
Steve

I do agree with the genuine Mikuni parts. I bought some 125 main jets so I could drill my existing ones stage by stage to find that "sweet spot". The bike wouldn't run for SHT. I pulled them and found, yes they were 125"s but they were a different brand and they were drilled differently. That made them run too lean.
Steve

swest wrote: It is a rare occasion to have to fully disassemble the carb rack....
IMO
Steve

I agree. Separating them is probably the best way if they are really in bad shape, but if they just need varnish removed after sitting for a year or 2 they can be cleaned without separating them from the rack. I have done this and had them operate as if they were new. Ed