Hey guys so I have a 2000 yamaha blaster I rebuilt the motor weisco crank and weisco piston bored .40 over. It ran great for about 10 hours then all of a sudden one day it started up and ran like crap. It just boggs down and has no power and even sounds bad and dies. I took it to a mechanic he said he fixed it but he didnt and he will no longer help me with it so I got screwed. I have tried cleaning the carb multiple times it has 360 main jet and 32.5 jet. Also the reeds look good but the carb and reeds did have excess oil built up on them and I'm running 32:1. Any ideas why it keeps bogging and dying on me?

 

If you are sure it isn't the carb, have you checked the exhaust? Usually exhausts plug slowly, so it sort of creeps up that they won't rev, but a loose baffle etc, can cause a sudden loss of power. bike will idle, but not rev. I go for removing it and starting up without the exhaust, only do this where nobody can hear you, and wear ear plugs. If most of the power is suddenly back, you have a plugged exhaust.

 

 

that's what I thought to so I ordered smaller jets and they should be here today. But it is bored .40 over with weisco piston and weisco crank, air filter and exhaust

 

 

I have on order coming today 330,340,350. So you think I should go way smaller then?

 

If the newer Jet didn't solve the problem and you have ruled out a few problem don't overlook an electrical probl like a bad CDI. I had a similar thing happen to my 2008 Big Bear and everyone told me there was no way it could be a bad CDI because they usually go bad and you lose spark completely. Mine would allow it to start and mimic such problems as a gummed up carb or worn out cam. Basically no power, it would bog down and didn't want to move. I swallowed my pride and my cash and took it to a "pro". They changed the Stator, rebuilt the carbs and $450 later it still ran like crap. Finally I bought a Chinese CDI off eBay, plugged it in and it ran like a dream!

 

 

Hey guys sorry it's been awhile but I finally got new smaller jets tried those and installed a new coil and cdi and still will not start. Any other ideas I could try?

 

Have you checked for a spark? Did you try it without the silencer?