Choke plungers

While researching DIY seals, we discovered these:
www.nichecycle.com/ncs/mikuni/parts-by-c...unger-by-mikuni.html

The critical dimensions are the same as VM28SS OEM Mikuni plungers within resolution of our digital calipers.

EDIT: Note that these have a raw brass finish, not the gray plated finish of the OEM Mikuni plungers.  If one is a stickler for cosmetic originality, these won't do.

We ordered a set to test in a rack of ribless Z1 carbs we run on one of our '72 Z1's. They fit & work fine. Ordered 32 more to mod all of our Z1 carbs & have a couple of sets on the shelf as carbs pass through our hands.

These differ from the Keyster plungers that lack the metering pin.  The Keyster plungers behave more like an ON / OFF switch due to lack of the pin, with little-to-no ability to feather the idle speed during cold start warmup in our experience. The pin on these seem to behave more like a coarse metering 'needle' at partial choke, which was likely the intent of Mikuni on the OEM plungers.

Disclaimer: we have no affiliation with Niche Cycle in any way.

Good Ridin'
slmjim & Z1BEBE

Nice find and thanks for sharing.  IIRC there has been a post here in the past that indicated Jets R us was also selling the plungers labeled the same way for vm29s. I am by no means an expert on this issue, but as I understand it the same item was used on all the Mikuni vm carbs.  I am sure that those who know more than I do will chime in on this. 

I bought from Jets r Us for the 29 smoothbore that Nessism rebuilt for me. gd4now I think your correct.

I used one from My VM 28's to replace one that was munged up on my 33's by the PO. Bought a new set from jetsRus.com for about $8 a piece. Didn't notice much difference but the peace of mind was worth it. 
Steve 

I have done a sort of short look at this and the same part number (16016-021) is listed for the VM22SS, VM24SS, VM26SS and VM28SS carb sets on the Kawasaki on-line part lists I can find. So I am fairly sure that the ones labeled for the VM29 should be able to be used on the smaller sets of carbs.  I was hoping that Zed might add his knowledge on this subject.

gd4now wrote:

I have done a sort of short look at this and the same part number (16016-021) is listed for the VM22SS, VM24SS, VM26SS and VM28SS carb sets on the Kawasaki on-line part lists I can find. So I am fairly sure that the ones labeled for the VM29 should be able to be used on the smaller sets of carbs.  I was hoping that Zed might add his knowledge on this subject.

Yes!  16016-021 are same unplated plain brass plungers on the 22,24,26 28 and Smoothies.
Part number 160160-017 denotes the plated type, some of which have different length metering needles.
Neither are suitable for the earlier Z1/SC carbs due to the differing length and lifter end.
Seals on these new items are still plain nitrile so susceptible to attack from ethanol enriched fuels as per the originals..
 

Do the Niche plungers (link in first post) fit stock Z1b carbs?

Kidkawie wrote:

Do the Niche plungers (link in first post) fit stock Z1b carbs?

The Niche plungers only fit the 3 screw top VM's as fitted to the z650, z900 , z1000's and vm29/33 smoothbores.
The plungers for the early vm26/28 two screw top SC carbs are obsolete which is what got me into developing the plunger repair service.

change to these about 2 yrs ago, might have mentioned in a thread, work fine, also changed to nylon lifting spools instead of the washer, and lift arms from 217 carbs, to allow for longer shaft, all good, all for first its 50 year rebuild!!, 

What mods to make them work, or anything even temporary?  I read a thread here about orings?
Have no problem sending to you for a rebuild but its June and my bike hasnt run right in 3 years.  Just went through the carbs but still get some black smoke.  Im betting on those plungers, mine are original.

Kidkawie wrote:

What mods to make them work, or anything even temporary?  I read a thread here about orings?
Have no problem sending to you for a rebuild but its June and my bike hasnt run right in 3 years.  Just went through the carbs but still get some black smoke.  Im betting on those plungers, mine are original.

The actual 8mm plunger head that sits in the body works but it's the length of the shaft and the lifter bobbin arrangement that is different on the later plungers.

As jwfels posted. the later ones can be made to work in the SC carbs but you have to change the lifter arms etc.

Actually..the choke plungers will interchange on the Z1B. The 1975 and late 1974 using the single wound return spring had the same dimensional type choke plunger except it was chrome plated. The 73 thru early 1974 were indeed different but you shouldn't have those. Note the first photo and different styles of lifters used thru the SC and SS VM series, organized early to late from left to right. Yours should be the one in the middle attached to rod. Next photo is original chrome plated NOS and correct for yours. Last is "probably" where you got that o-ring concept from and is what i included in some past threads i'd attended here. Have been doing this for years and it's just a cheap way to "renew" the choke plunger original plunger seat. It's just a 1.5CS X 1.5ID X 4.5OD O-Ring i superglue to the original pad after cleaning it up. Costs less then a stick of gum ha. Just want to seal off the choke petrol access when high vacuum is created at idle, this does it.