Duane,

Listen to Jim T. His remarks are about spot-on.

Other thoughts: A $60 engine like an OS 25LA-S is an excellent choice for the ARF Flite Streak. It is ABN (nickel plated sleeve, not chromed), designed for easy and dependable operation, and not so heavy that balancing a Flite Streak becomes a problem. It is also pretty economical; you should be able to get enough time from the TF ARF Flite Streak tank.

Not everyone runs a 4/2 break mode any more, especially with the newer designed engines. Like the OS LA-S (and their R/C cousins) as plated brass sleeve engines, you want to break them in on the fuel and at the RPM you'll fly them at. They are manufactured with a slight taper to the sleeve, which opens to the right clearance at operating temperatures. So, the initial wear time (break-in) should give the engine those conditions as soon as possible. (This applies to ABC and AAC, as well; AAC is chromed aluminum sleeve. The first 'A' in all these designators is aluminum, for the piston.) Instructions for the OS LA series cover break-in nicely.

And, as they are much like their R/C cousins, they are designed for more RPM than you might remember for stunt. The way to keep airspeed and laptime reasonable is first, with a flatter pitch prop, and also with line length, fuel, plug and all the other goodies that are involved. You want the engine to run at the proper temperature, so you don't want it struggling with a too large or too high pitch prop - either/both will run the engine too hot.

Even the oil rquirement is a bit different. Good R/C fuel (by which I mean around 10% nitro, with around 20% total oil, about half of which is castor) does well. So, no more happy hours scraping off a deep layer of castor...

For a 25 like the LA, a 9-4 or 9-5, or even a clean 10-4, keeps things in "lower gear" so you don't overload it and fry it. Don't be surprised if launch RPM is around 12K - the engine is happy there.

The single wheel on the Flite Streak is no problem if you have a friend to launch for you. It is only a slight problem taking off out of a stooge. The plans on the original TF Flite Streak showed launch position as outboard tip on the ground, nose slightly out of the circle. It's up to you to NOT pull too hard on release. If you do, you might drag the onboard tip to the ground and turn the model in at you. A no-no...

From a stooge, I found hanging a rag over the outboard tip kept it down nicely. It didn't ride along very far as the model took off...