I've noticed that my TH .75 engines are a bit funny on the carb too.

After a good break in--I set the low speed for instant throttle response--and then I'll never touch it again. No reason too.

The high speed needle is funny. It must be the taper on the end or something.

The engine doesn't really like to be set rich enough to hear the RPM drop off. I peak it and then back it off about 6 or 8 clicks and then go fly it. I point the nose up to check for a lean condition. No problems. But, if I actually back it off enough to hear it get a little rich and start dropping RPM--then it's slobbery.

I've got a damn good ear for a 2-stroke. I never use a tach. I can tell when they are lean or rich by listening to them as I tune.

You can always tell when you've hit max lean because you'll click the needle 1 more time and it won't gain anymore RPM. Then click it a couple more times and nothing happens. But--you click it again--and it sags and slows down. I can hear that with my ears and feel it in the needle when I'm tuning.

So, I find that spot where you give it that first click and nothing happens. I kow I've just hit max lean and max power. So, I back it off 6 or 8 clicks. The engine doesn't slow down. Most glow engines will slow down when you go 8 clicks rich from max lean. Not the TH .75. Not mine anyways.

I've got 8 of them. 1 is in the box and 1 had to get sent back for service. So--I've got 6 of them up and running. They all act the same way when tuning.

Anyway--when it's 8 clicks rich--it'll run fine. Point the nose up and it'll pick up maybe 100RPM and hold steady for a whole tank if you hold it there.

If I keep going rich untill I actually hear it slow down--they run like dog poop. Too rich. Slobbering and burbling. It effects the transition too.

I guess--what I'm saying is that I'm used to tuning finicky engines now. I'll bet the .46 is similar to the .75

It's gotta be the way the taper is shaped on the end of the needle. Maybe it's a really narrow taper. Or a very steap taper that drops off real quick.

My mind tells me that it's a narrow taper. You can keep tweaking and tweaking--you'll get small changes in RPM as the needle goes in or out. But, when you get too the shoulder on the needle--then it gets real sensitive because your off the taper and into the straight part of the needle shaft.

I don't know[:-] I just know they are kinda finicky. I been ramblin'. Sorry.[]