I have a Super Tigre .75 that won't quite, literally. The throttle is closed completely, no opening visable at all, in fact its closed beyond that. I thought there might be an airleak around the throttle so I seated the carb to the crankcase with plenty of pressure. Close the throttle, crank down the trim, hit the kill button on the transmitter, zilch, the thing keeps on running on a dead slow idle. Only way I can kill it is pinch off or pull off the fuel line and then it still runs for 30 seconds.

Everything else about the motor runs great. Super power, slow smooth idle, (with a tad of opening visable in the carb), great transitions, normal top end rpm.

Anyone that can tell me what gives and how to make this thing stop?

bob branch

Well it's nice to see a different post now and then... most of the time it's about guys complaining they can't keep there engines running!

But seriously, if it doesn't quit, that mean it still gets air. I figure you knew that...
So check everything: the backplate, the case (a crack from a crash), it can suck air through the pinch bolt hole... don't overtighten the pinch bolt by the way, it can deform the case and/or carb.
If everything is tight, mount the carb and pinch bolt with a little silicone or something... see if that helps.
Does the carb barrel have play in the carb body...?

Things like that...

This is a problem???? I remember days of yesteryear when we would have given an arm or a leg for an engine that would run and idle like that! I have some TOWER engines that behave that way and I don't think it's a problem.

My, how times change.

Bob - You've got a great engoine there. It'll sereve you for many uears when properly cared for.

Rudeboy is correct about the air leak and chances are it is leaking around the carb mount, needle threads, or back plate. I would coat the carb throat (outside) and backplate o-ring with automotive axel grease. and install. Take care not to roll the o-ring on the back plate when insterting. Insert this plate using a twisting motion (small amounts of CW and CCW) until seated. If you are still having the same problem, then place a small length of fuel tubing over the needle valve and seat, as the air is most likely entering through the needle threads.

Good luck and let us know how you fare.