3W70iUS run problems

[mark786]

I have a 3W70iUS that I bought used so I don't know the actual age or history. I have run about 3 gallons through the engine when it started running funny.
It seems to run well most of the time but it seems when I go inverted it throttles back. I can increase throttle and it picks up. Acts like the motor box is loose and the throttle linkage changes when it goes inverted. I do get some miss occasionally but it it always starts well. I don't think it is the fuel tank.
I pulled the reeds out tonight and found them to be in pretty good shape. However they have a small burnt looking spot on one side. It doesn't appear to be large enough to cause a leak. Any ideas?
Thanks,
Mark

[Dan767]

You may be running a little rich. You can try leaning it out just the slightest amount on the top end.

[torquen]

Try adding a small plate to cover the hole that is on the side of the carb. If this hole gets direct air pressure it will change the engines rpm's. You can use something like a thing piece of metal off a Pepsi can or solder a tube to the hole and run a piece of fuel line off the tubing and into the fuse.
Garrett

[sweetpea]

You talk about it missing sometimes but always easy to start.

3 things can be happening there.

1) ignition is overheating

2) if this is the new ignition (4wire) I've seen that a 5cell nicad or NIMH just doesn't have the amps to push the ignition after its warmed up and the motor will sound like its missing. Switch to a LION 7.4 no reg (only on the new ignitions) and the problem goes away.

3)ignition is going bad