The big is a 87 and the problem is when its cold out, or the bike has been sitting for a while it will not start with out being pop started, but after we finaly get it started from pulling it, the bike will start fine the rest of the day. We have checked for air leaks, and cant find any. Its a 87 with a 38mm carb, a paul turner high rev pipe, a pro design head and I think 19cc domes.

 

Im the owner and its actually a 36mm carb 22cc dome coolhead

 

The next time you let it sit for a while, before even trying to start it, check and see if there's a build-up of gas in the cylinder. Check it first before you touch anything or move it. Try getting a reed kit for it, that made my old Honda 250R I use to have start a lot easier. If you do have excess gas in the cylinder then you prolly know what's wrong.