xr 650r main jet problems

I have a 2001 xr650r. Its uncorked with a uni filter. I replaced the piolet jet with a 68s and I put in a 175 main jet. When I accelerate it just bogs down. It just goes bbwwwup. I put in a 155 main jet and it runs good. I read where everone runs 175's no problem. I am stumped. Please help!!!

Did you or someone else also install the non-epa intake or cut out the restrictor plate in the stock manifold?

Did you or someone else also remove the airbox restrictors?

Did you or someone else also install the HRC exhaust tip or open up the stock exhaust tip or install a better flowing aftermarket exhaust system?

If you haven't done any of these or just some of these, then your bike won't run as it should.

Also, the jet sizes you should be using depend on your riding temperature, altitude (pressure) and to a lesser extent, humidity. What altitude and temperature are you riding at?

Like Qadsan is saying, there are too many variables you left out. Answer the questions and we can better help you. I, personally run a 172 main as I found the 175 to be a tad rich.

Yes to the HRC tip, yes to the opened air box intake and yes to the intake. I have not adjusted the needle and could it be the float level? Thanks for your help

Also I ride in the desert about 3000 feet and 60 degrees.

You're almost on your way to a better running bike :thumbsup:

If you're bike is bogging shortly after idle, then try changing your needle to the 2nd clip position from the top.

If you're bogging immediately off idle, then try adjusting your fuel screw (aka pilot screw) as follows. Make sure your engine is fully warmed up and set the pilot screw to 1.5 turns out. When tightening the pilot screw, make sure you seat it lightly or else you may damage the screw needle and or seat if it's tightened too much. With the engine running and the 68s installed, turn the pilot screw clockwise until the idle slows. Then turn the pilot screw counterclockwise until the idle slows again. Make a mental note of how many turns you made in between the low idle points. Then turn the pilot screw half way between the low idle points to finish the adjustment. Ususally that's good enough, but you can fine tune it from there by finding the spot that gives you the highest idle speed inside that window. If you turn the adjuster counterclockwise and the idle doesn't drop down, then you need a larger pilot jet. If you turn the pilot screw clockwise and the idle doesn't drop down, then you need a smaller pilot jet. After adjusting your pilot circuit, re-adjust your idle speed to spec if necessary.

The float level is also critical and should not be overlooked if the above doesn't resolve your issue. As the float level rises (more fuel in the bowl), so does the hydrostatic pressure on the jets, thus more fuel flow in all the circuits. Based on my experiences, the you'll want your float level set at or between the stock setting or 2mm lower for best results.

Another thing not to overlook are the vent tubes. Make sure they're not plugged up or melted shut, otherwise it can mimic a float problem.

Thanks I'll try changing the needle today and let you know. I tried adjusting my pilot screw and I truned it all the way in and there was no change.

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