im building a 4*60 and i can't find any supertigre 75's.

Use an ST90 then and just practice some throttle control. The 60, 75 and 90 all share the same cases and weigh pretty much the same.

Edit - If you are willing to order from Canada, the mail order shop I use is showing them in stock. You might want to check first, I have had items shown as in stock back ordered before. Their indicator is usually correct, but not always...

http://www.greathobbies.com/productinfo/?prod_id=SUPG75


Mark

Go with the ST 90 or any 90-91 engine. I've had 2 of them, both with .91 2-strokes (OS .91FX & Magnum .91XLS), both use an Ultra Thrust tuned muffler.

An ST 90 won't be too much.

I had two ST G90 engines for several years. They have the same mounting dimensions as the 75

Go with the ST 90 That is the engine that I had in My Four Star 60, it realy flew it great. Have fun.