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KLX300R Runs rough-need help!

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Hi guys, I've been lurking in the shadows for a while and gaining info on how to fix the rough running condition on my 2007 KLX300. Mileage and hours are unknown, I bought this bike two weeks ago. I was not afforded the opportunity to test ride it, but the guy selling it took it for a test ride and it seemed to run fine. I got it home and other than a little low end stumble, it ran fine. I took the bike out last weekend and the bike ran really rough just off of idle. If the throttle was whacked open, it would accelerate fine. I installed a dynojet kit, no improvement. I installed a #40 pilot jet, no change. I reverted back to stock jetting, still does the same thing. The air box lid is off, the pipe is stock with the end plug removed. I checked the valve lash, it's within specs. I have checked the intake boot for leaks, as well as the slide diaphragm. Both are good to go. I removed the spark plug and kicked the engine over to check for spark, and noticed that it was a little hard to kick over even with the spark plug out. Any suggestions on what else to look at?

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New or old gas? I would take the carb out and give it a good cleaning, replace any old gas with new.

The gas is fresh, and I have cleaned the carb..I guess I forgot to put those details in there.

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Is this a possible air fuel mixture? Where is your adjustment screw set at? Keep at it, I don't have as muh knowledge as most here do, just trying to give some ideas.

The only "adjustment screw" is the pilot screw. It controls the mixture at idle and a bit above.

Ride on

Brewster

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You've definitely been hitting all the problem areas. Given that it's occurring just off idle, it sounds most likely that the pilot jet is clogged or the adjustment is off a little. Even the smallest speck of grit will kill the pilot circuit. Hope the problem gets remedied.

Not sure about the hard to kick over without the plug in... Hard to assess without actually doing it myself, but there's some drag from valve train. Any more than what's reasonable sounds like a bearing or cylinder issue.

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It does it just off idle, or if I hold the throttle steady in one position. It sounds like an engine that is misfiring. I am going to put a fresh spark plug in there today after work and see what happens.

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Hmm, Maybe a silly question but I run the highest octane in my 01 300 are you running the highest? What about your plug are you on stock plug? You might be able to run a hotter plug. Let us know how the new plug works out.

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New plug didn't do a thing. But..I have made a few discoveries. The engine is running rich, even with the stock jetting. Don't ask me how, I can't explain it. I inadvertently ran the engine with the petcock off, and it started to clear up a little bit. I then adjusted the float height to 19mm. No change in condition, black smoke at the exhaust, and runs rough. The jetting is back to stock now, and it still runs like garbage. It acts as if there is a plugged air passage, but everything is clear. I pulled the carburetor completely apart and used carb cleaner and compressed air to make sure it is indeed clean. I am at a complete loss for what to do. I am tempted to buy a new carb for it.

EDIT: I noticed that there is a considerable amount of play where the needle goes through the slide..could that be a contributor?

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Well a pumper carb would be quite the upgrade. So I can help more, I would just play with the fuel adjustment screw and see if you can lean it up a little. I would throw the dynojet back in and adjust from there.

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SONOFABITCH!! I found the problem..I was looking at the parts fiche and noticed that there was a part on the list that I haven't seen in my carb..the jet needle is missing!! Gonna order one and go from there..

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You should ask the jerk you bought it from for the jet. They don't just fall out.

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They fall out if the air bleed pipe is removed for cleaning..nevertheless..I received the jet today, 15 minutes later the bike is idling happily in the garage. I did a victory lap around the block..very happy with how it is running now.

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They fall out if the air bleed pipe is removed for cleaning..nevertheless..I received the jet today, 15 minutes later the bike is idling happily in the garage. I did a victory lap around the block..very happy with how it is running now.

Was it the jet needle or the needle jet?

Ride on

Brewster

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Hi guys, just finished reading forum, DerTeufel you have completely discribed my problem exactly, I bet it's missing from my carb to, I also never saw it when I stripped carb after buying a bike that runs like a hairy dog and wont idle. Thanks.

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Try running it without the airbox in place. I removed the backfire screen from mine and it definitely was running rich. It may help verify that you are running rich and point you in the right direction.

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