I broke in a NIB Tower Hobbies .75 engine the other day. Nothing new to me. I've got 8 of these engines.

But, this one was so tight when fresh out of the box, that I was afraid to even turn it over for priming. I ended up running the throttle to full and then blowing through the muffler/pressure line to force some fuel into the engine before I fired it up.

It was so tight that it was literally squeaking at TDC. I was flipping it with my chicken stick, and it would squeak every time it went past TDC. I had to flip it about 6 or 8 times before it finally fired.

It was so stinking tight that it wouldn't even stay running--even with the glow igniter on it. I didn't even have time to get my hand on the throttle stick and run it up to full before the piston would seize at TDC and kill the engine. I was cringing. I was thinking that this couldn't be good for the rod. I wanted it to stay running just long enough for me to get it opened up to full throttle. It was squeaking while it was running at idle for the 1/2 second or so before it would die again. I was starting to get a sick feeling in my stomach. It just kept dying and sticking the piston at TDC. I had to start it 3 or 4 times before I finally got the throttle slammed open and removed the igniter.

I finally got it started and got my hand on the throttle to run it up to full speed for the break in. I removed the igniter immediately and ran it at a rich 2-stroke.

I started out with a cheap Top Flite 10-8 and Omega 5% fuel. I had it running close to 15,000RPM and still rich. I only ran it about 3 or 4 minutes before shut it down for 20 minutes and let it cool.

I kept increasing the prop size slowly and I kept the RPM up near 15,000RPM and rich 2-stroke during the break in. I went up in size to several different props.

(I've got 6 props that I use to break in these TH .75 engines. They start out small and slowly get bigger as the engine gets stronger. Some of the props are chopped down versions of larger ones, and some of them are stock. I got a little felt bag that I keep these props in--and it's specifically for breaking in the TH .75 engines.)

I went through three 12oz tanks of fuel before I called it good enough. I backed it off peak about 7 or 8 clicks and decided to go fly it.

This one is a SCREAMER!! The best one yet. It's turning a Pro Zinger 13-6 on 5% Omega fuel between 12,500--12,800RPM. Thats NOT peaked RPM. Thats my flying RPM with it 7 or 8 clicks on the rich side. I'll lean it out 1 click per flying session untill it's done.

I've just never had an ABC engine this tight when new. Maybe I should remove a couple head shims and see what it does.[>:]

GOOD GAWD!! If there was ever an engine that needed to be mounted in a speed plane--this is the one. I'll bet this engine would turn an 11-7 or an 11-8 at close to 14,000RPM--maybe more. I might take this engine out of my 3D plane and put it back in the box for now. I can take another engine out of the box and run it in my 3D plane.

I got a GP Cosmic Wind Minnow Sport racer ARF here. That might be just the right combination of airframe and rediculous power.[sm=bananahead.gif]