Upgrading to a vm22-133 round slide mikuni

[EdK]

Hello all,

I'm brand spanking new here and I appreciate any help you all can offer me. I purchased what I believe is an genuine mikuni vm22-133 but I have some concerns about the jets.

I bought a new pilot jet that went in with no problems. The main is a different story though. It seems that the main that came with the carb is rounded at the top with an o ring on one end. The replacement mikuni main jet that I got is a hex design that bolts in no problem but has no provisions for an o ring. It sits in a boss adjacent to the pilot jet. Should I be concerned about the difference in the 2 designs? Thanks,

Ed

 

[Havasu Dave]

Ed, have you seen this write up on the comparisons? (Click Here)

It's been quite awhile, but there is a definite difference between the main and pilot jets between the Chinese version and the less Chinese version.

 

[EdK]

Thank you Havasu Dave. I actually already have both of these carbs. I purchased the "chikuni" and it bolted right up. With that carb I had hard starting issues as it was too rich at idle and fouled my plug quickly. I purchased genuine mikuni jets not knowing they wouldn't fit. Stumped on where to find "chikuni" jets, I purchased what I believe is a genuine vm22-133. That carb looks just like the genuine carb in the write up. When I opened it up the pilot had the mikuni square logo but the main had no markings and looked different than the replacement main jet I already purchased.

I will get some photos up of what I'm looking at.

 

[EdK]

I'm having a lot of trouble uploading photos to this thread. It says my post has been denied because it contains a URL. I'm using a kindle fire. Hopefully I can figure this out today.

 

[KMC3420]

I'm having a lot of trouble uploading photos to this thread. It says my post has been denied because it contains a URL. I'm using a kindle fire. Hopefully I can figure this out today.

Click Here For Instructions to upload pictures

Also, seems like the most common jets in the real deal Mikuni are:
130 Main & 12.5 Pilot

Real mikuni jets

 

[ole4]

Those are for the cheap chikuni.

 

[KMC3420]

Those are for the cheap chikuni.

Well crap, thanks ole. I fixed the link. Let me know if you have a better link? I have a genuine mikuni in the mail.

 

[EdK]

Thank you kmc and ole. I think I've got the photos down now.

Here is my copy chikuni

Here's the genuine vm22-133 I've replaced it with

Here's the inside of the vm22-133 that shows the round main jet in question

These are the 2 mikuni main jets in question

Finally, this is the bowl off the genuine vm22-133. You can see that the round main fits into the recess and the o ring makes the fit snug

 

[EdK]

Thank you KNC3420, could you post the link to the fake jets you found? I have another motor I may throw the chikuni on.

 

[KMC3420]

Thank you KNC3420, could you post the link to the fake jets you found? I have another motor I may throw the chikuni on.

Chikuni Jets

Good read on tuning Mikuni's
Mikuni VM22-133 Tuning

Another option for Genuine Mikuni jets:
Real Mikuni Jets #2

 

[gasgas300]

ok been in the motor cycle repair buss sense 1975 u have to diff type of carbs there the the brass with the oring is not !! the jet in that style carb the main jet is located under the large hex bolt on the side of the float bowl

 

[gasgas300]

u have to different types of carbs there the jet with the oring is not!! the main jet in that carb the main jet is under the hex nut in the side of the float bolw

 

[EdK]

Thanks guys, that write up is great. The main is on the bowl plug.

My previous experience with Mikuni has only been with CV carbs, that's why I thought the tower next to the pilot held the main. To make matters worse, the jet bolted bolted right in! Thanks again guys.

 

[Foster143]

I've been banging my head since last night trying to figure out why the "main jet" just didn't seem right in my VM22. Never seen a main jet located in the side of the bowl like this. Was glad to find this information though.

 

[DaddyJohn]

I've been banging my head since last night trying to figure out why the "main jet" just didn't seem right in my VM22. Never seen a main jet located in the side of the bowl like this. Was glad to find this information though.

My '75 Yamaha DT250 has a Mikuni VM of this variety. I suppose the main advantage of that layout is quick jetting changes and/or cleaning of the jet by virtue of easy access. I wasn't too familiar with that layout with respect to the VM range myself prior to that...

Here's a video of one being inspected if anyone is interested in looking at this type of main jet arrangement.

 

[paulsblocks]

Had the exact same concern when I bought one of these carbs. The main jet goes into the bowl. Unscrew your drain plug all the way and take it out and you will find the main jet. Make sure u put that o ring jet back in. (Its not actually a jet)