Starter plunger 94 Wombat

[matt glascock]

Hi All, Does anybody know if the starter plunger on the stock Wombat carb is can be rebuilt? The plunger will not remain in the "on" position when pulled out. This is the push/pull type starter plunger and not the lever-activated type. Thank you!

[Bill2001]

There is a spring/detent in there but I don't think there are available. The entire starter plunger is a replacement part. You might be able to get a usable part from a junk carb.

[matt glascock]

Thanks Bill. I have a similar plunger from the carb off an old YZ100 (VM22 I think) but it's shaft is about 4mm shorter so would likely not work. SH is currently out of stock. I will check HPI. I've found that I can hold up the plunger and kick it through slowly a few times to "prime" the motor and then it will fire. I guess that will be plan "A" until I can find a replacement. I was hoping there was a secret to get to the detent and refurbishing it.

[Bullfrog]

Matt,
Have you kicked into the "they aren't making any more of those" frame of mind . . . and closely examined the plunger system to figger out HOW the latching detent works . . . and WHAT might be causing it to not work?

My money is on you figgeren it out and coming up with a fix.
Ed

[Bill2001]

Sudco is the major Mikuni distributor and they should have it. I may have a usable old starter plunger VM24 Wombat carb that you can have. I've since switched over to the new lever-starter carb and the old carb is a worn parts carb.

[matt glascock]

Thanks for the vote of confidence, Captain. I'm going to go all "surgery" on it. I'm certainly in the "they aren't making any more of those" frame of mind at this time. One thing I've learned about surgery, though. Getting things apart is easy. Putting them back together so that they function properly is where you make your bones. Failing that in this scenario, it appears that Bill will jump in and save the day (many thanks, Bill). Now, it looks like I have some figgeren to do. I'll report. Thanks Fellas!

[Hydraulic Jack]

Does it look something like this:

https://www.jetsrus.com/individual_part ... 52_su.html

I know it says VM16... but that is just a parts reference. It is listed as the starter plunger for the VM24.

Since this one fits the new VM24 it may or may not have the same dimensions, but measure yours carefully, research the website carefully, and send them an email to verify dimensions on the new part. SH has been getting them from somewhere, and Sudco isn't the only retailer. I have found parts for old bike carbs that fit, or could be made to work. I think the detent on yours is friction between the plunger shaft and the plastic or rubber top under the knob.

[Bill2001]

Got and it's good. It springs In/Off and detents Out/On. The rubbery disk is not rock-hard and is uncracked. The "critical" dimension, the inner length of the rod, spring, etc is 25.0mm.

[matt glascock]

Thanks fellas! I will take a careful measurement of the rod. Jack, the part you pictured looks exactly correct down to the brass nut. I did notice the rubber cap on mine is a bit dry rotted so that may be the cause if its condition has a role in the friction component of the detent. I'll dig deeper and report. Thanks again!

[matt glascock]

Great news here!! So lifting up the rubber cap revealed an empty groove machined into the plunger body. Why would they go to the trouble of machining a groove here if it didn't serve a purpose? I took a closer look at the plunger off the YZ carb and sure enough, there is a circlip of sorts with a flat side that fits into the groove (which also has a flat aspect that is open on the deep margin) and this, in turn, indexes with a slight bump in the plunger rod under a little spring tension to hold it in the "enriched" position. Happily, the circlip from the YZ carb fit perfectly and I'm officially back in business. So, the good news here is that these plungers are at least, to this extent, rebuildable. If anyone experiences this problem, there is a solution. The next question is whether or not Mikuni sells these circlips for replacement. Otherwise, they would be easy enough to fabricate but it would take a rigid spring steel wire of about 0.030-0.035 gauge. Thanks all!

[Bullfrog]

Nice figgerin' !
Ed

[Bill2001]

Good deal. You've shown how this part can be repaired and how these "becoming NLA" can have am extension on life.

PS-- good advice, cap'n.

[matt glascock]

Thanks for your help and encouragement fellas! Always good to figger another trick to keep our Hodies rippin'! I'm trying not to think too hard about where the original spring clip ended up. I mean, how much mischief could a small piece of spring steel cause rattling around in the carburetor or engine . Happily, I don't see any way it could get in there - even in pieces - right?!?!?

Best,

Matt