Need help on 85 R!!

[whiteman350x]

Working on an 85 250r. It has a new sleeve and fresh bore. It has been put through about 8 heat cycles. Went for a ride today. It cranked and ran fine. I had gone about a mile and it started revving without me giving it any throttle. I tried to shut it down and it would not die. I choked it down in 6th by holding both brakes. Pulled the plug and it looked about right, slightly darker that it should but not black. Changed plugs and headed back. It started it again so I pulled the choke up (it has an 86 carb). It cleared up for about 200 yds and then started revving again. I shut it down and walked home b/c I did not want to fry a new motor. I do not know anything adout this motor, I just got it, built the top end and started trying it out. Where would you guys start? The whole electrical system including the stator and flywheel came off of my old motor and I never had any problems with it.

Thanks for any and all help.

Whiteman

[Lots_Of_Nothing]

Check the intake for leaks, check your throttle cable to make sure its not pinching up. And also make sure you have a good steady stream of gas. Thats where I would start.

[RideRed250R]

yah sounds like a air leak somewhere, also make sure its getting gas and not starving casuse some times a twostroke will rev when its not getting enough gas.
adam

[Orangecnty250r]

Happened to my friend when he had an air leak----- he scrambled as you did and it only shut down by covering the exhaust.

[86250RZ]

same thing just happened to my Nephew this weekend after he installed a 39mm carb and new intake on his R, we tried adjusting the carb all the way down and it still wanted to rev way to high. So I decided to check the fitment of the carb to the boot, it was fine, so then I decided to look at the intake and see if he had tightened all the bolts, sure nuff that was his problem.We tightened all the bolts and fired her back up and she ran like a champ.

[hrc85250r]

hey, yur carb could be vibrating itself so much that the slide is staying open, and make sure your needle isnt getting caught...and your pilot is screwed in and not loose...