Well, I bet the experts in this forum Rob Lee and SWJohnesy etc. would be better at pinpointing it, but I'd say sounds like it COULD be a jetting problem.
3 questions:
1) Is it just in a certain rpm range? Or does it happen at ANY part of the rpm range when you lay down the throttle. If it's in any part of the powerband when you roll on, may be a problem related to the throttle cable?
2) Have you checked compression?
3) Is there any aftermarket part(s) in the carburetors? Are the stock jets still in them?
If this is only happening at a certain range (ie/ around 4000rpm)... chances are it's a jetting problem that is likely pretty easy to fix.
If you're the original owner and haven't changed anything, likely not the jetting, unless needles have been damaged somehow. Then it's a tougher one to diagnose I'd say...
Where's that Rob Lee guy when ya need him, huh?
3 questions:
1) Is it just in a certain rpm range? Or does it happen at ANY part of the rpm range when you lay down the throttle. If it's in any part of the powerband when you roll on, may be a problem related to the throttle cable?
2) Have you checked compression?
3) Is there any aftermarket part(s) in the carburetors? Are the stock jets still in them?
If this is only happening at a certain range (ie/ around 4000rpm)... chances are it's a jetting problem that is likely pretty easy to fix.
If you're the original owner and haven't changed anything, likely not the jetting, unless needles have been damaged somehow. Then it's a tougher one to diagnose I'd say...
Where's that Rob Lee guy when ya need him, huh?