i have a tower hobbies .46 in a superstar that i bought a few months ago. when i first started flying it, i could take it out in my backyard and tune it so it ran perfectly. it would idle forever, and jump up to peak RPM without hesitation, then come back down to idle fine. then i would take it to the field right then and try to start it at the field with no luck. i would need to completely re-set the needles to the factory settings then tune it again. i put it away for about 3 months and just took it out to fly. i can not, for the life of me, get this engine to run right. i just fooled with both needles for about 45 minutes until my ni-start died and i had to come home. any ideas what is wrong?

Personally, I believe you answered your own question:

"i have a tower hobbies .46"

Dr.1

Well my experience with the Tower 46 is that its a tempermental
beast at least until broken in well. And break in takes quite a while
since its very tight. You WILL be chasing the needles around
for a while until it settles down.

A new pilot at our field has one on a Tower trainer and at first
it seemed to run pretty good after a bit of break in on the ground.
We did have to keep readjusting the needles after almost every
flight. But it seemed to settle down after a few flights and seemed
to be running well. However sometime later he started having
a few deadsticks with it so I worked on it again for him.

What I found was this motor does NOT like the Tower plugs
which are supposedly rebranded OS #8s. Even a new plug
didnt improve things. I put in a Fox idle bar plug in it and it
behaved like a whole different motor. So I would definitely
try a new plug.

The low speed and high speed needles interact so you
have to do quite a bit of tweaking to find the "sweet" spot.

Another thing...this motor leans out in the air more than
any other motor I've worked on. So you really need those
needles rich on the ground. If you set it so its just "a little on the
rich side" on the ground it will lean out and overheat once
in the air.

I think this is where most people go wrong with this motor and
is probably responsible for some of the bad rap people give it.
They end up running it too lean and overheat it and end up
damaging the motor before it even has a chance to get broken in.

Mike Hammer

Yup! That's a Tower 46 for sure.

Just means it is a bit hot is all. The faster the rev's the more it unloads, the more it leans out.

Open the low speed needle up a half a turn, and see if it will start. Those high
strung engines need to be set a little rich on the low and high speed needles
because of the power they produce....power equals heat.

Set the high speed about 4 clicks richer than where you think it is just right.

FBD.