Today me and my friend went riding. We was riding out in an open area, and his Banshee acted like the plugs was fouling out. Then it died. He went to crank it up and he couldn't kick it over(the kick starter would not go down.) We think the crank bearings are locked up. Is that the problem or could it be something else?

 

the motor is defitely locked, may be pistons froze on the cyl walls, tae the head and cyl. off t find theprob. look at the crank nd examine it carefully

 

Oh can I relate to you. Had the same problem. The lower rod bearing decided to weld itself to the crank pin, this is bad. What I did is tear the motor down, pulled out the crank and sent it to Palm Beach FL to Tony Doukas Racing. The build a great crank. They have three performance levels priced from $350 to $500. I got the $500 high performance crank. It is trued and welded uses hot rods and uses MAX roller Mag side bearings and MAX PTO bearings with 10 ***** instead of 7. It also includes rebuildable inner webs and center bearings. The standard crank uses hot rods, stock style bearings and trued and welded. The only fix is to have the crank rebuilt. Good luck.
eric

 

Banshee_16 I called Mission Yamaha today and talked to Ted he is the guy that built the 420 to begin with, a crank rebuild would be $270, he said it may be the piston. He said to tear it down and give him a call he would step me through checking key areas. Also he asked about compression I said 175 psi, he mentioned cheap gauges give false readings probably 10 psi off or more. So I dont know how accurate that gauge is. So how was the fireworks? Still have all your fingers.

Later

 

Yea, i still have all my fingers, but we only shot 2 cases between the three family's. oh well. Maybe it is the pistons cuz that would be cheaper. I got 120 compression from mine with your tester, so I think that is what is supposed to be. I think your gauge is good. We can tear it down any time you would like. Too bad your gonna miss the race this weekend. $270 isn't bad for a crank rebuild though. It will be fun tearen it down and all. LOL

Later

 

I will pull the head this weekend to see if its just the piston. If that's not locked up then I may see if Jennifers dad can help it might be a good idea to let someone thats done this stuff before have a look at things. I'll call saturday afternoon and let you know whats up.

Later