This bike has been a two year project. Bored to 71mm with a wiesco piston. Boyensen reeds. All new seal and gaskets. Polished the ports and head. Exhaust is clean. K&N air filter. Carb has been gone through.

Here is the issue. In order to adjust the idle to maximum speed before adjusting the idle speed screw I have to turn the idle air screw at least three turns out. Has a miss up to about 4,000 and the it cleans up and runs strong. It just seems to be running rich based on the performance and the spark plug. Black sooty carbon. Running an NGK iridium plug. Any suggestions?

Thx

JR

my DT175MX is a bit like this at the moment, I have tried two carbs and both the same so i'm discounting that for now. Next thing is to swap the boyessen reeds for standard ones and see if thats it!

you could also try fitting the standard filter back in if its serviceable...just in case the K&N is more restrictive, its and easy do so worth a try.