I am looking for suggestions on what to do. I have a fairly new Nitro Sport that I has only had about 3/4 quart of fuel through it. I took the E/Z start off and replaced it with a pull start. Well, that didn't seem to work out too well. It was really hard to pull and didn't recoil very well. So I yanked it back off and put my E/Z start back on. When I took the pull start off, the dang thing sprung out on me(yes I'm a newbie, you can quit laughing now) Well to make a long story short, my engine was hard to crank for some reason, I checked for flooding but there wasn't a whole lot of fuel in it. The next thing was catastrophic. I pulled the head off to see if maybe I had damaged something internally, and while I was trying to get the sleeve out I damaged the piston. After looking at prices for a new piston/sleeve set and stabbing myself in the thumb with an x-acto knife, I am wondering if I should just purchase a new engine. I wanted to make it a Pro .15 anyhow, so the cost of a new head, carbeurator, and piston/sleeve set would cost more than a new engine itself. Does anyone use a different brand of engine? Is this the only kind that will work? How much better is a slide carb vs. a rotary carb? Will a slide carb work with a Sport? I had looked at some O.S. Engines, I like the 15 CVX. Any help or suggestions will be appreciated!