quick question about choke flaps

I wish there was an easy way to mass produce solid choke plates. Seems like it should be easy, but it's not a real simple shape.

If you get rid of the flaps, as some have done, you could put in a "Primer". They sell these for Snowmobiles, try Dennis Kirk or Ebay. Around $15 I think.
You would Tee it to your fuel line, and then to each Carb on the Manifold/ or throat vacuum fitting. It is a hand pump basically for squirting a small shot of fuel into the motor, just like an accelerator pump would. Where to mount it? Well maybe a bracket back down under the carb rack?

If you could find some aluminum shim stock (like used to shim motors and pumps) you could do it I think. I grabbed some stainless stock, but wasn't able to cut it small enough without deforming it. I don't have access to aluminum stock though becuase I work at a chloralkali plant, and aluminum would last 10 min here.

Brass shim stock would be easy enough to come by, most any bearing supply/ or machine shop would have some. But thick enough?

I don't know if brass would react with the aluminum carb body somehow. The problem with other metal would be the bending to connect to the control arm.

I don't think we'd need the primer, but thanks for the suggestion. The problem is the bikes like to run with some choke even after starting until it gets warmed up for a few minutes. So we'd still need the sliding plate. If it can seal off all the way, that should be enough to start fine.

Let me see if I can find a good pic.

I had two flaps missing as well when i bought my bike. When i took the top end apart those two pistons had some dings on the top of the pistons. The rings were slightly pinched in a couple of areas. I was able to free them up with little effort and the bike still runs good!

I still think the easiest way to fix the flaps is by filling the hole with epoxy and like apbling says you just adjust you choke lever position to approx 70-80 closed.

It would be cool if we could get some place in China to pop these out for a couple bucks each.

Maybe for a very limited run, carve them out of billet on a CNC. Anyone know if CNC can do something this small?


EDIT: I just noticed the pin is walking out on the flap in the photos above. You can see it poking out on the right. That carb is not in use yet, though. I'd need to re-peen that before using.

This one below is pressed in correctly.

yeah some of my pins where almost falling out, some where so stuck I didn't think I'd get them out! Not sure if a CNC could do this... my worry would be the tool marks it would leave might deform the flap. I had planned on getting the actual door close enough and leave a ton of extra slack for the hinge, that way I would have enough torque to fold it over the pin (which would be already in place.

The epoxy gives me a piece of mind knowing my machinist skills won't be whats between me and having someting come loose and cause more damage.

BTW, I don't think the bodies are actually aluminum, are they? I thought they were some sort of zinc alloy... at least they don't seem to be aluminum.

I meant to CNC a solid plate with no flaps etc on it. Just one big solid choke plate... just to eliminate the need for epoxy etc.

The bodies, I assume are basically pot metal. I think that is some sort of aluminum/zinc/ alloy... maybe some tin? Don't really know.

I did noice a little white crust where brass meets body on some older sets that sat for years.

Maybe brass would be ok though. I think it would be stronger than aluminum shim and probably less brittle than stainless shim.

Remember, I'm talking about the entire choke plate, not just the flap. In order to be able to install the plate and control the plate there would have to be some sort of flexible link to attach to the control arm.

Just thinking out loud I guess...

just took mine out for a test ride with the new "modified" flaps, choke works great now. Still stumbles a bit down low but up high it seems ok. Need to adjust the clutch also, or maybe put some new clutch plates in.

It would seem the best way to go about it would be to somehow stamp them out like the original, but then they would still be thin like the oem ones....I dont think it would be that difficult to cnc a solid one, maybe when i take the carbs apart ill investigate making an autocad file of the choke plate, but no promises, i really only use autocad for architectural work.

Since i am a machinist i can draw one up in SoliWorks and machine one out sometime. I am very busy right now so it will have to wait a little while.

harm wrote:

Since i am a machinist i can draw one up in SoliWorks and machine one out sometime. I am very busy right now so it will have to wait a little while.

No hurry. (At least not for me ).

I just don't know if molding solid plates would be easier than machining solid plates out of billet, or not.

Glad it's running better Apbling.

EDIT: oops, I mean DanHalen