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Jd Kit or Keihin conversion?

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I need some input i hate to spend the money on either, but i cannot get my bike to run right. It seems like its just the needle b/c its building up at low speeds slightly and wont idle unless the idle screw it all the way in to the point its recessed in the lock nut. but i have no idea where to begin to look for what needle i need. I have heard many good things about JD and that it solved all their problems, but then also some people have said it didnt work well. What do yall think will solve the problem? I would much rather spend the 75 rather than the 250 on a keihin conversion but if the keihin will solve my problems and not cause huge jetting issues between seasons i would not mind spending the money. I just want it fixed and running right/idling before it causes me to do something i will regret such as trading for a 4T.

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JD kits work very well in some bikes. The 02-04 CR 250's (I'm guessing the 01 could be added here as well) are not one of those bikes. I spent the money and while the JD needles it did what a needle is supposed to do it did not cure the shortcomings of the TMX carb on the bottom end and nothing will imo. Do yourself a favor, buy a PWK and end your troubles once and for all. You will not regret the money spent :smirk:

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You hate to spend $ on jetting? They're not expensive at all, and if you air screw has to be all the way in for it to idle, then that's a clear indication your pilot is too lean, and first off check your service manual for where you're supposed to be at this temp and altitude, then compare.

I hate to say it but too many people ignore jetting until it's a in your face type of problem, when in actuality you really need to learn it to have a good running bike and keep from tearing up your motor from lean conditions. Jetting is everything.

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no not single jets i meant a kit such as JD if its not going to work i figure spend it once fix it once, and No not my air screw, The idle screw w/ the locknut. My air screw is usually positioned at about 1.5-1.75 to get the best performance.

And what all do i need for the conversion? just the carb slide it in, run the cable, and there yah go? is it all direct fit? what are some good baseline jetting specs to start w/? idk if itll matter but i have a gnarly pipe, shorty, v-force 3's and run 32:1

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if you have the TMX carb without the TPS, you will need a screw top/long body keihin. If you have the newer TMX with TPS, you will need the newer flat top keihin/short body.

I tried both the JD and the Keihin in my 05, when conditions are right, the JD kit rips in the Mikuni, problem is even with the JD kit, it is still temperamental to minor temp changes. I was still constantly fiddling when riding in the woods throughout the day.

I felt the Keihin gave me more low end for my woods riding and I only occasionally need to mess with the airscrew.

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You hate to spend $ on jetting? They're not expensive at all, and if you air screw has to be all the way in for it to idle, then that's a clear indication your pilot is too lean, and first off check your service manual for where you're supposed to be at this temp and altitude, then compare.

I hate to say it but too many people ignore jetting until it's a in your face type of problem, when in actuality you really need to learn it to have a good running bike and keep from tearing up your motor from lean conditions. Jetting is everything.

He said idle screw not air screw. The TMX carb is very different from the Keihin you know. Setting idle is beyond easy. You hafta loosen a lock nut and then use a phillips screw driver to adjust.

He doesn't want to know if it's OK to pay a few bucks for jets. He's trying to ascertain why he should either spend 75 or 250 to fix the chronic TMX trouble.

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My experience with the jd kit in the tmx has been positive. I also have a pwk to compare, but don't want to ruin a good thing now that the tmx is dialed..

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Ok ok I got ya. I have heard negative things regarding tuning the TMX. I was thinking $75-250 is alot for jetting lol

I know guys in my area don't really have any trouble with that carb, it must just be in a certain environment that it's a nightmare...I would switch carbs. I'm about to go to the airstriker from JD in the spring/summer.

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Ok ok I got ya. I have heard negative things regarding tuning the TMX. I was thinking $75-250 is alot for jetting lol

I know guys in my area don't really have any trouble with that carb, it must just be in a certain environment that it's a nightmare...I would switch carbs. I'm about to go to the airstriker from JD in the spring/summer.

I didn't have any issues jetting my friends 01s but from what I've been hearing the tmx on the 01, although the same Carb until 04 (???) its not nearly as hard to tune on the 01 as it is on the case fed engines.

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if you have the TMX carb without the TPS, you will need a screw top/long body keihin. If you have the newer TMX with TPS, you will need the newer flat top keihin/short body.

I tried both the JD and the Keihin in my 05, when conditions are right, the JD kit rips in the Mikuni, problem is even with the JD kit, it is still temperamental to minor temp changes. I was still constantly fiddling when riding in the woods throughout the day.

I felt the Keihin gave me more low end for my woods riding and I only occasionally need to mess with the airscrew.

Ok can someone send me a link of an example of the carb id be looking for? Does it have to come from JD and pay the 250 sum odd dollars or can i find a used one thatd work like from another bike or sumthin? I just have never looked into the swap so i am clueless on what i need to be looking for. and yes i have the one with the tps, will that still be used with the conversion?

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Ok can someone send me a link of an example of the carb id be looking for? Does it have to come from JD and pay the 250 sum odd dollars or can i find a used one thatd work like from another bike or sumthin? I just have never looked into the swap so i am clueless on what i need to be looking for. and yes i have the one with the tps, will that still be used with the conversion?

TPS goes away. Go to TT store and search for PWK. That's what you'll get with JD's custom jetting for your model. You could use a 92-98 CR250 Keihin PJ if you like. Other PWKs may fit if they're 38mm.

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So what yall are saying is the JD kit will not make it better at all? Im not looking for a top notch race bike, i short shift, and spend much of my time on trails or a small track built on my friends property. The main thing i want to get rid of is the slight building up, which i know can be caused by the needle. If the JD kit will not improve this then i guess my only option is to look into the PWK but i would hate to go through all of that if a simple needle will change the slight problem i have?

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OP I will be upgrading to a PWK airstriker this spring. Not that there is anything wrong with my PJ at all on my 98, but I'm just doing it as people have raved about the airstriker. This carb is in top notch condition. Just installed a full carb rebuild kit and have countless brand new extra OEM gaskets, float assembly, and jets for it, so when the time comes I'll be selling it for the cheapness, especially if it was to a TT member.

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A common problem on many bikes is the factory needle. As bikes are sold to different countries all over the world they even come to our land, Sweden, and the factory don't want any seized bikes to come back when they are sold, so they put in really fat jetting to eliminate seizing. if you have problems to keep idle speed up it's probably too rich on either pilot jet or needle, maybe both. The standard needles are way to fat usually. I would check the numbers and digits on the needle and go up maybe 2 sizes in base diameter, and also check what pilot jet is in. if you are riding mostly in the woods you can go quite lean. that eliminates plug failure and will give you a smoother bike witout bludder at throttle opening. i think you can get the Mikuni quite good and maybe install a divider plate for a better bottom end power, but it will never be as good as a keihin PWK 38 AS. I use PWK's in all my bikes, including my CR 500.

Johnny

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cheap and easy way is to look for a used carb on ebay or in the classifieds.

THe 38mm screw top I have is from a 2000 cr250, the stock 2000 needle actually worked pretty well in it. Many of the KTM's had this 38 mm carb also, so KTMtalk classifieds is a good place to find them.

I beleive the screw tops are typically the long body, meaning the top of the carb literally screws off. THe flat tops are typically short bodies and the tops are held on by two screws.

Long body screw top:

http://www.ebay.com/itm/KEIHIN-38MM-PWK-AIR-STRIKER-CARB-CARBURETOR-/230701535836?pt=Motorcycles_Parts_Accessories&vxp=mtr&hash=item35b6e2125c

Short body flat top:

http://www.ebay.com/itm/KEIHIN-PWK-39mm-Carb-KTM-125sx-Carb-/150728274779?pt=Motorcycles_Parts_Accessories&vxp=mtr&hash=item23181af35b

My 38mm keihin I have came from a 2000 cr250, I paid $50 on ebay. My 36mm flat top came from a 2006 ktm300, I paid $75 on KTMtalk.

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If you find that my 98 Keihin PJ will work, well just know that it's an excellent condition carb, and I'll be selling it in the spring.

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so can i use either the long body or the short body? You said i needed the flat top one in my bike b/c it had a tps right? Do you simply just unhook the tps and run it w/o it? It will not cause problems in the way the bike runs?

Also, a friend of mine brought up a good point that the smoking and bogging could be caused by leaking crank seals is there a way to test this or a way to tell. I know my bike smokes, but nothing to terrible unless like i said i idle for a while or do really slow woods riding and it builds up it will smoke once i take off again. i dont have terrible spooge just some around the tip and some mist looking spatter on my side plate. Shold i look into the crank seals as well, or does it sound more like the typical mikuni problems?

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well see thats what i was thinking, and it doesnt run super rich or spooge really bad. It only spudders or runs super rich after a time of slow riding or idling itll have to clean out slightly. In higher rpms it runs super crisp i was just trying to clean up the bottom end for woods.\

So, i can use either the screw top or the flat top pwk? Sorry about all the questions i just wanna make sure i order the right carb. Does it have to be the 38mm? or is that just the best?

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