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klx300 jetting help

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I own a 2001 klx300 with a stroker exhaust and header all free mods. Can anyone give me ideas on jetting using a dyno jet kit at alt. from 5000 to 12000 ft. thanks

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I own a 2001 klx300 with a stroker exhaust and header all free mods. Can anyone give me ideas on jetting using a dyno jet kit at alt. from 5000 to 12000 ft. thanks

I'd start with a 128 MJ. When you get up over 9-10k, you're going to want to go to a 124MJ. Clip in the middle position when at lower elevations. Go one clip leaner (lower the needle) when going up in altitude. If you don't want to mess with it when going up higher, go with the leaner jetting and you'll probably be OK, but I'd start with 128/middle clip position first. You'll have to mess with the pilot screw to find what works best at your altitude/weather. Good luck.

Bill

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I've got a pretty much identical situation (mods and altitude). I put in the 124, needle at the middle. Took some tweaking to get the pilot adjusted, but it seems to run right at 1 1/2 - 2 turns out, depending on temperature. There's no popping on decelleration, but I may put the 128 in just to see what happens. I'd rather it run a bit rich if anything.

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Colorado, try adjusting the needle one step leaner. Depending on your altitude and style - in other words, where you usually have the throttle - ie:WFO or mid throttle - you may really like how it runs. (crisper).

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Thanks Bill. I lowered the jet and took it for a spin. Some hiccup right off the bottom, but I think this is the pilot and dreaded CV curse. I'll fiddle a bit more. As for just off throttle to WOT, it cooks! Pulled some nice wheelies on the backstreets and drifted into the garage before the neighbours got too choked. Will stay with this as it's bound to dial in better as the weather gets warmer. Thanks again for the tip.

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Thanks Bill. I lowered the jet and took it for a spin. Some hiccup right off the bottom, but I think this is the pilot and dreaded CV curse. I'll fiddle a bit more. As for just off throttle to WOT, it cooks! Pulled some nice wheelies on the backstreets and drifted into the garage before the neighbours got too choked. Will stay with this as it's bound to dial in better as the weather gets warmer. Thanks again for the tip.

Yeah, that sounds like your pilot jet. Do you have the plug over the screw exposed so that you can get in and adjust the pilot screw?

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Yes. I did all the mods to the carb, including drilling out the plug to access the pilot screw and drilling out the throttle slide for better low rpm vacuum. Made a big difference. I'll do my best to eliminate the stumble until I can afford an FCR and a big bore kit. Until then, I'll just read jealously about all of you who have done those mods.

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I bought the muffler, headpipe, crankcase breather and jet kit from Fourstrokeworks. I am a newbie at carbs, so I asked Jerry to send me the specs for the carb in my area. I live at about 5600'.

Here are the carb specs that he provided:

Pilot 40

Needle NTC1

Clip position (from top) 3rd

Main 128

Fuel Screw 1 1/2

Air Screwn 0

Main Screw 0

Pilot Air Jet 0

Spark Plug CR8

I only had to make one change and it was the pilot from a 35 to 40. After I put it together, it seemed to run fine. The snow finally lifted, so I will be heading to the dirt soon.

Slowturtle

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slowturtle or Bill_P: I didn't get a pilot jet in the kit from Dynojet. I assumed this was because it wouldn't make too big a diff. However, the stumble right off idle isn't going away, so perhaps this may be helped a bit by decreasing my pilot jet size? Any thoughts? Thanks.

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Generally, one size pilot pretty much works for everyone. Jerry sometimes goes up one size. Due to the extreme cold where you are and the high altituede, you may need to try a different pilot. Have you had the carb apart to clean everything out? Especially if the bike sits for awhile, the pilot jet opening is very small and can get gummed up and clogged easily. Good luck.

Bill

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I did take the carb apart when I put the kit in, and was pretty keen about not letting anything fall into or clog passages. I put Stabil in all the bikes and ride them around the yard/block every week or so just to make sure they don't gum up, but I will pull the carb off again to change up the pilot jet. Couldn't hurt to try, and since winter is hitting us again, I've got time to fiddle with it.

Thanks again Bill.

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Would similar settings apply to the KLX 250S assuming same elevation conditions? I've got a full muzzys, air box opened up, uni filter, and the dynojet kit in hand. thanks

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I think it would. The engine/carb is identical except for the bore. If you've got the free mods and a pipe, it should flow very similarly to the 300. Give it a whirl and see. I'd recommend putting in your best guess, and seeing how that goes. The jet kit is pretty easy to tune. Best of luck.

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Thank you all for the information. My computer died and i have been in mourning.

cqctt1

klx300 with 331 kit in process

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Am just wondering if a larger pilot number increase or decreases fuel to air ratio. Does a higher number allow more fuel or more air? Anyone know?

Welcome back cqctt1. Let us know how the 331 kit works.

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