I have a 1981 Suzuki GS250 I had added the wrong oil and an additive that clogged it all up and was leaking oil from the exhaust. I removed the oil pan and the filter and cleaned it all out w/Chemtool added 10w40 motorcycle oil and a new filter. Made new gaskets and closed it all up. I also replaced the generator (alternator), lubed the chain and cleaned out all the gunk off where the chain meets the transmission (I'm sure it has a common name but I'm not a motorcycle mechanic, I'm more used to cars). Anyhow, before I ripped into it, the bike was working just leaking oil. After 3 weeks of it sitting there it won't start after putting it back together. I also replaced the spark plugs. FYI-this is a list off all that's new: plugs, generator, oil filter, oil, new gaskets where needed, new ignition coils, new battery. Before when it wouldn't start I would just take it up the hill roll down and it would kick on after slamming it in 2nd gear. Not this time. I charged the battery, rode down the hill and it felt as if once I put it in gear it would sort of lock the back tire and I could not really hear any compression. I know the tranny is working because it would engage the gear but it won't turn over. Is there something that I might have overlooked? Any help would be very much appreciated.