Off-idle hesitation on a 2002 XR650R

Hi All,

Looking for some help with an off-idle hesitation on a 2002 XR650R. I've got two days until the Adelanto Grand Prix race this Saturday and I just installed a Uni air filter using the Uni air filter support frame and no backfire screen, cut the Team Honda breather holes into the left side panel, installed a Pro Circuit T-4 muffler using the stock header, and I removed the airbox plugs three years ago. The bike will start on the first kick but now, when I quickly turn the throttle from idle to 1/2 throttle, the engine bogs for a split second then revs to mid RPM quickly. If I quickly turn the throttle from idle to full, the engine bogs and stalls. If I turn the choke half on, the engine doesn't bog as much. If I turn the choke full on, the bog is completely gone and revs from idle to mid RPM really quickly but doesn't run well at high RPM with the choke full on.

It has a 175 main, 68S pilot, B53E needle on the 3rd clip, and I've tried setting the fuel/pilot screw anywhere from 1/2 to 5 turns out but I can't get rid of the bog. I tried a 70 (not a 70S) pilot but it didn't make a noticeable difference, it still bogs. The float height is set to 16 mm. Temp. is around 50-60 degrees. Elevation at home is 800 feet, which is where I'm working on the bike. Elevation at the race is 3000 feet.

What should I try next?

What affect does changing the clip position on the needle have?

Thanks in advance.


The air to fuel ratio is wrong. Did it do this before you opened it up to recieve more air? :) You might try turning the idle up. Raising the needle will allow more fuel on the lower end.

If this started after the breather mods, you probrabl need to go a little bigger on the main ~178 or so

Thanks for the responses so far.

Before cutting the breather holes in the left side panel, removing the backfire screen, installing the Uni air filter frame, and installing the Pro Circuit muffler with the stock header, I had a Uni air filter, XR's Only backfire screen, Big Gun full race exhaust system with header, and I switched back and forth between a 172 and 175 main. It ran okay like that but didn't bog off idle like it does now.

Thanks for the help,


Sounds like you stretched your Power Band. The 650R Power Band is very wide but you don't want it to stretch and break. See Qadsan for the part #. :):D

Leaving for San Felipe in an hour, just a little giddy. :)

Pumper carb..

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