Choke assembly leaking air

Patton, I think I have already mentioned once that the plunger pad is the source of the leak. I believe this because I have seen it happen dozens of times. All you have to do is jiggle the choke knob and the plunger will usually seal for a short time before the idle jumps back up. We replace plunger pads, as needed, on all our rebuilds. We have the pads manufactured. They must be pretty precise to work properly. Last, it MIGHT be possible to flip over the pads; problem is, that if one side is hardened and deformed, the other side will be almost rock hard and doesn't seem to me that it would be the best way to provide a seal but it might work IF you can get a hardened piece of rubber out of the plunger without damaging it.

wiredgeorge wrote:

Patton, I think I have already mentioned once that the plunger pad is the source of the leak. I believe this because I have seen it happen dozens of times. All you have to do is jiggle the choke knob and the plunger will usually seal for a short time before the idle jumps back up. We replace plunger pads, as needed, on all our rebuilds. We have the pads manufactured. They must be pretty precise to work properly. Last, it MIGHT be possible to flip over the pads; problem is, that if one side is hardened and deformed, the other side will be almost rock hard and doesn't seem to me that it would be the best way to provide a seal but it might work IF you can get a hardened piece of rubber out of the plunger without damaging it.

Thanks, wg. You're one of my heroes, so no argument here.

Am unaware of what tests were performed, choke knob jiggling or otherwise, but realized the original poster's diagnosis blamed the wrong part. And certainly agree about leaking plunger pads needing to be replaced. Just wasn't so willing to accept the original poster's air leak diagnosis being limited to an enrichener circuit air leak, especially when the wrong part was initially blamed. So asked for more info underlying the diagnosis.

My understanding is that the original poster is unable to find a new plunger, and even more unable to find a new plunger pad. So -- if the plunger pad is indeed defective -- he is relegated to other possible remedies such as manufacturing his own plunger pad, possibly flipping it over (just grasping at a straw) -- or better yet, sending the carbs to you for a proper rebuild.

Maybe I have simply missed noticing something that would obviate any other air leak source besides the plunger pad.

Thanks again!

If someone actually has the actual diameter and thickness of this pad I can probably make them where I work. Also what material do you guys think it is? Nitrile rubber?

Lou

i apreciate the responses here Patton, wire george i thank you very much, Yes i did mis lable the corect part that was leaking air it was in the acual base of the enrichener body base not the plunger itself. All in all i found a very cheap very ugly used set of BS 38's and used the plunger and plunger enrichener body as a replacement. Never was able to fab any parts that worked they are very very tight clearances that have to be exact so thak you all

The choke plungers that came in the refurb kits I bought from Z1 inc. didn’t have the pin like extensions on them. Is this a problem? The choke seems to work OK and the bike idles fine? Just curious. Thanks

KZ900UAE wrote: The choke plungers that came in the refurb kits I bought from Z1 inc. didn’t have the pin like extensions on them. Is this a problem? The choke seems to work OK and the bike idles fine? Just curious. Thanks

The pin is there for a reason and although the pattern ones will do the job without they are not as good and you lose the sensitivity of the stock ones.
I now offer a reseating service for the original plungers on the VM24,26 and 28 mm carb banks with ethanol resistant Viton if you have issues with the new ones.

I've tried to synch my carbs with repro choke plungers and haven't been very successful. But if yours are fine I wouldn't mess with them. And hang onto your old ones just in case.

OK thanks... I’ll leave well alone for now!