84 250R surges when closing throttle hot

[Wi200x]

One thing that bothers me on this machine is that when the engine is good and hot it will surge when letting off the throttle intermittently. It will even do it at idle sometimes when extremely hot. I wonder if the seal on the dry side of the crank is letting air into the engine intermittently or maybe there's enough carbon floating around igniting the fuel prematurely? Anyone else have this experience? Also with the new piston and bored cylinder the kickstarter will kick back bad at times. Sure has more power as I can't keep the front wheel on the ground in first gear on pavement.

[jeffatc250r]

Could be right about the seal, the surging is from a lean mix, try adjusting the air fuel on the carb, turning it in and see if that helps, if it doesnt then i suggest a leak down test, could also be an intake gasket leak. Check your intake bolts.