First build, no idle, 4 stroking, etc.

[Tippyman]

Try removing the cable from it and reinstalling the plunger and return spring only.
Also, there is a black rubber seal on the end of the plunger. Is it deformed in any way?

I removed the cap and took the cable out completely.

I slid out the brass plunger and saw it had a little rubber nub on the end, almost like someone had melted a piece of wax on it. The rubber was actually at a very slight angle and you could see where the nipple in the bottom of the cylinder (that I suppose the rubber blocks off) was hitting one side of the rubber harder than the other. I took a small piece of rubber (actually the tail off of a fishing lure) and cut it to match the bottom of the brass. I stuck it down in the cylinder and reinstalled the plunger and spring and cap. My hope is that it will now seal up that nipple better.

I then put all the hoses back as described earlier. Fuel vent pointed down, left nipple capped, and the upper and right nipples open.

Can't test it til tomorrow, I guess we'll see.

 

[Tippyman]

Well, made some progress.

With the hoses the correct way and the plunger "fixed" it runs just like before. Still doing the air filter thing. However, once I got it nice and hot, it will idle for about 30 seconds before slowly slowing down and turning off.

 

[Tippyman]

Another development! (kinda)

I was riding it around some more seeing if getting it extra warmed up would help it idle even better. Then the carb fell off!

The CNS carb has a plastic sleeve inside the choke neck that fits tight over the manifold. Then there's a rubber seal at the back that presses up against the end of the manifold. I'm thinking that maybe there's an air leak here since the carb was loose? Even so, why would the idle be OK for 30 seconds then slow down and die? With an air leak wouldn't it ramp up?

I'm going to try some gas-proof gasket maker all around there since its as tight as it will go...

 

[killercanuck]

Then the carb fell off!

Well there's your problem, heh heh. Maybe because you have to have it jetted really rich with the leak to ride around(higher rpm, more air getting in) so at idle not as much air is getting in, causing it to flood itself out? Just a theory.

gl.

 

[SnowyRangeDesign]

Wow, this sounds like my experience with a brand new 48 cc Grubee at 7000 ft elevation. I haven't tried removing the air cleaner yet, but I will. This thing won't idle and only runs decently if the choke is about 1/2 engaged.

Thanks for any ideas.