Which Pit bike motor for my ATC70

[250rmanfmf]

Hey guys, looking to see what peoples opinions are on the pit bike motors in the atc70. I will be flat tracking it. I have been looking at the 140cc Piranha motor. I do like the Pitster 125cc one too. Looking for a kickstart and manuel clutch. I know many people are running the Lifan's but was wondering what the other options are. Also what cc is getting too much for the frame. I plan on extending the front section of frame a couple of inches to inprove turning and for extra length. Any help would be great

Thanks
Tyler

[110klt]

My son had a Lifan 125cc pit bike for a year or two. The bike frame and parts were POS. However I will give the Lifan motor it's due. It was every bit as fast as his 125TTR, started every time and never gave any problems untill he jumped it and the chain slapped the case and cracked it spewing oil all over. IMO not really the engines fault, and I also see they make a big bore kit for that engine too.