09 Yz 85 Flat Spot On Acceleration

[AUSSIE80]

HAVE A 09 YZ 85 THAT HAS A FLAT SPOT ON TAKE OFF, AND SOMETIMES CONTINUES DURING GEAR CHANGES, PROBLEM IS INTERMITTENT. HAVE TAKEN IT BACK TO DEALER WHO HAS SERVICED BIKE TWICE WITH NO CHANGE, BIKE IS WELL MAINTAINED,RIDDEN FAST BUT NOT HARD, BY A 13YO NEW FUEL USED EVERY RIDE AND CLEANED AFTER EVERY RIDE, IS THERE A COMMON PROBLEM WITH AN EASY FIX, ANY HELP APPRECIATED

[Jason Hall]

I would start by moveing the needle (Under carb cap In slide/throttle valve). I would guess It's lean. If the bike falls flat when you start to throttle In. I suggest you lower the clip on the needle.

[AUSSIE80]

jason, thanks heaps mate for your reply, will do mod as recommended and let you know of result shortly. i have in past only had older bikes i.e pe 400, it 490's etc nothing new , so i was just a bit wary about doing this to a new bike.