Originally Posted by jwalters
Thanks for the input TS.
I'm traveling for work right now, but I'm making an intake adapter so I can use my motion pro leak down tester. I've already replaced the piston rings, but that hasn't fixed my very hard starting bike. Rebuilt the carb, but it still only runs with choke at partial throttle. So I'm guessing crank seals next. Until I do the leakdown test though, I'm just guessing.
Check crank for main bearing wear, if its ok and the bike hasnt been left standing for a long while, then the seals are almost certainly ok. If its simply a matter of not running, then if you have a good spark and compression, the first thing to try is a squirt of aerosol brake cleaner directly into the carb mouth, ideally while a helper is kicking the bike over. In many cases, when bikes have been standing carbs will be blocked internally, and will not start. Brake cleaner method shows if thats the case, and that you either need a new carb, or maybe try ultrasonic cleaning on the OE carb.