No manufacture makes 100% perfact engines theres always going to a few bad ones your going to run into and have problums, and did you talk to STS and see if they would replace it?

I hav heard a few bad things about the LRP aswell, one guy said he could only get 5mins on a 150cc tank. I can get 8 running break-in setting on my STS 30.

I use a 14 tooth CB in my buggy, and works good. I have heard the STS engines will keep up with the $300+ but I have not had the chance to run with a guy that has a $300+ engine to test that, oh on STS engines take break-in slow drive it easy for a gallon maybe two before its comepletly broke in. when its broke in they say you can pull the plug out and you should be able to turn the engine over with no effert (with the PLUG OUT)
let me know if you get an STS engine and I can send you the break-in method I use.

gsfreak what ofna pipe did you get?