I have a 1998 yz400 I bought a week or so ago. I rode it to storage went the next weekend it ran but the throttle was sticking open. Took the carb off there was a screw that backed out and was rubbing where the cables go. Tightened sprayed the carb out with some cleaner and played with it some. It still sticks a little bit but seems fine. Put it all back together and it won't start. I'm obviously not too familiar with the bike but I pulled the plug there was a little bit of carbon on it but nothing crazy. Checked spark it was there but seemed a little weak. Also the hot start button or choke whatever it is won't stay out when you pull it I have to hold it. It has the bottom end, trans, and stator set up from a wr with a yz top end. The guy I bought it from had receipts from the recent engine rebuild. He said it was in storage for about a year and he took the carb and cleaned it when he pulled it out to sell. Any ideas?