TRX Pro.15 Rebuild
 

Hey RC people... I was wondering, when I rebuild my Pro.15 is it necessary to replace the connecting rod, clips and wrist pin? I am going to order my parts soon because the engine likes to loose compression when its warm and no matter what I do (since like last week) it always over heats.
Another question, is a quart of fuel enough to break in the engine? I'm doing the five tank break in when I get the piston and sleeve.

Change out the cylinder/Piston and rod as a group. Make sure the crank pin is still round and not oval.

It depends. The pistons in these little engines are so light weight, they really don't stretch rods like you see in a conventional gasoline engine. However, the bushings do wear, and cannot be purchased separately. I've rebuilt many with only piston and sleeve, but if the rod bushings are worn, I will replace it as well. On OS engines with the floating wrist pin, I replace it, but generally leave wrist pins alone unless there's a reason to change it out.

As for break-in, I typically do about 100 times the engine displacement. So for a .15 (2.5cc), that'd be 250cc of fuel, or about 3 tanks (most 1/10 tanks are ~75cc)