670 mxz runs rough...

[clemmer]

hi people..... i was wonderin if someone could help diagnose a problem i'm havin with my '99 670 mxz. Just bought it from a guy in B.C., and it starts and idles great, but doesn't wanna open up when i go to ride it. It has self adjusting carbs, and i was told it wouldn't have to be re-jetted, but is it possible that it needs to be re-jetted? I put new spark plugs in, but didn't make a difference, and the machine will occasionally backfire... AND.... i did get to enjoy a rip of a ride one day, for about an hour..... in which it started out the same way, but eventually straightened out and purred like a kitten.... Please,... any helpful suggestions would be deeply appreciated...... or is it possible that i got sold a sled with a bad motor?

 

[DRD]

Make sure it has solid top plugs, not the screw on type, change the plug boots, gap the plugs, 018" (if memory serves) and clean the DESS cap with an eraser. If the plugs are arcing in the boots it messes with it's tiny electronic brain. First things I'd check.

 

[Modman]

hi people..... i was wonderin if someone could help diagnose a problem i'm havin with my '99 670 mxz. Just bought it from a guy in B.C., and it starts and idles great, but doesn't wanna open up when i go to ride it. It has self adjusting carbs, and i was told it wouldn't have to be re-jetted, but is it possible that it needs to be re-jetted? I put new spark plugs in, but didn't make a difference, and the machine will occasionally backfire... AND.... i did get to enjoy a rip of a ride one day, for about an hour..... in which it started out the same way, but eventually straightened out and purred like a kitten.... Please,... any helpful suggestions would be deeply appreciated...... or is it possible that i got sold a sled with a bad motor?

how old is the gas in it?

Are you sure its firing on both cylinders?

Do a compression test and see what it says, should read about 130-135 psi.

Carbs could probably use a cleaning also.