Guys, I need some serious help.


So I took the time to break in my .21 xm, and ran about 3-4 tanks out of the water, with a cooling system rigged up and the high speed needle in the neighborhood of 3turns out. Everything seemed to be going well, until I tried putting it in the water. Turns out when I was running the motor out of the water, I was running it backwards. Nowhere did it mention to reverse the polarity of the starter, I made the mistake of assuming it was correct. So I realized this and switched the polarity, and went to run the boat.

After some tuning and messing with the carb, I finally got the boat to move a little bit ( 28mph by radar). But it took forever to rev out, even when leaned to like 2 turns. I didnt want to go much further than that. The motor just doesnt feel right when I grab the flywheel and kick it over. When I grab the flywheel and rotate it slowly, I can move the flywheel about 1/8inch freely ( doesnt grab at all). When I continue to spin the flywheel I get what is best described as a horrible clicking noise, something is definetely not right here. I have had the motor apart, and I can see no visible damage to the piston/cylinder/connecting rod. However when I turn the motor over with the backplate off and watch the assembly, I can see a tiny hitch at bottom dead center. This is so frustrating, I have ran nitro cars my whole life and never had these kinds of problems!!

I think I'm just guna tear the thing down and put a new connecting rod in it. Maybe running it backwards stretched it out or something. Also, what kind of torque should I be putting on the water cooled head? When I snug the allen screws down good it feels like the piston is hitting at the top of the stroke. And when I back them off just a touch it feels smooth? Ahh this .21 XM is a strange beast. Someone set me straight please! Anything to keep me from sending this back to O.S. for them to hit me with labor charges!! Open for suggestions guys, fire away!!