Abrupt Throttle Response XR650R

Greetings,

I searched but couldn't find much dealing with what I feel I have as a problem. Any advice or tips are appreciated. My 2002 uncorked, but otherwise stock, XR650R is difficult to control at low/off-idle throttle opening. Maybe it's normal but it feels like the throttle is too quick. On the road or fast trails it's not a problem. Where it's bad is when picking my way over rocks and very rough, slow conditions. The *slightest* movement of the throttle causes lurching which causes another movement of the throttle which causes lurching which........

There's no air leaks around the carb, I've made sure chain is ajusted and there's almost no slack in the throttle. Is there a slower opening throttle available?

rick

What pilot jet do you have?

I think this was a problem reported by quite a few riders. Mine does have this problem but I did help it by making sure the throttle cable didn't have too much play as this exagerated the on/off throttle.

Fitting the Mikuni TM40 carb helps I believe.

I've just learned to grab a little clutch when the going gets slippery.

>What pilot jet do you have?

Presently, 68 with 170 main, and B53E needle with clip at 3rd position.

Originally I did the 68 and 170 with the stock needle raised to 4th position. Riders following me said I smelled rich. I had it dyno'd with a EGA and was told it was too rich. I can't remember the % but the mechanic advised lowering the needle one position which I did. Seemed to run fine but a little harder to start and maybe more abrupt. That's when I carefully ajusted as the chain, removed all slack from the throttle, and installed the B53 needle (clip in 3rd). It seemed to help some but it's still pretty jerky to me. BTW I ride mostly 1,000-4,000 feet but plan on riding Southern Utah next Spring which will be 2,000-9,000 so I don't want it too rich.

rick

My son had the same problem with his 650R along with not being able to jet it to his satisfaction. We installed an Edelbrock pumper, improvement in all respects. No more abrupt throttle response,cold starting is improved, hot starting is one kick, even if the bike has been dropped. I've dropped it a couple of times and it actually kept running and all I had to do was pull in the clutch and pick it up. Another benefit is the ability to lean or enrich the mixture on the spot with no disassembly. I rode it in Colorado in August, and all I had to do was give it two clicks to the lean side and it ran great at all altitudes with no further adjustment. Downside, it is not cheap.

>My son had the same problem with his 650R along with not being able to jet it to his satisfaction. We installed an Edelbrock pumper, improvement in all respects. No more abrupt throttle response,

Thanks Creeky,

Today I experimented by alternating between the 68s and 65s pilot and the clip in the 2nd, 3rd, and 4th position in the stock needle and the B53 one. I guess it's meant to be. Or I buy a new Mikuni or Edelbrock like you.

rick

Creeky, what did you have to pay for your edelbrock and ordered from who ?+

Procycle has the Edelbrock carb kits, hang on to your wallet. :applause:

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