Husky WR250 Keihin, Mikuni Swap

[WLKDX]

Just wanted to post my experience in case anyone else is having problems with TMX carbs on husky's. I picked up a used 99 WR250 and had hard start, poor low-end, stalling issues from the start. I did the top-end, reeds, rejetted numerous times, no relief. I happened to read a post about Honda CR250's with the same 38mm TMX carb and the advice was to toss it. I picked up a 38mm PWK and the difference is dramatic. Bike starts first kick, pulls smoothly at any rpm and doesn't stall constantly. The carb fit right into the old boots, it is slightly wider opening to opening, but there is enough play. The best mod I could have done, makes me wonder how well it would run with the 36mm PWK like the KTM's are running.

 

[Norman Foley]

Good to know. I've been lucky with my '00 WR250. Starts and runs well. I ride it all year and just make jetting changes for temp. What jetting do you have in the Keihin? Can you use the stock throttle cable?
Norman

 

[COLEMANAPP]

I have a modified Keihin I've used on my Husky 360. On that the bowl had to modified to fit above the case. I also had good luck with the mikuni and left it alone since that Keihin was almost TOO much on the 360. You can use the same cable but I think I needed a longer adjuster on the handlebar. Let me know what you think it does on your bike. Maybe I'll give that Keihin another try.

 

[WLKDX]

Your right about the throttle cable, it was a little tight when
turning left, I rerouted it and it was fine. I didn't need to do anything to allow it to clear the case. I have it jetted a bit rich for the winter here in N.E. 180 main, 48 pilot, #5 slide with the needle in the middle clip position. I don't think it has any major power increase other than running very smooth with no flat spots and stalling.

 

[scottyr]

Very interested in this swap. What needle did you use?

 

[WLKDX]

I will have to look, it was a stock needle for a kdx 200 that I had in an extra carb for that bike. The slide that came with the Kiehin was a #6. Needle clip in the center.

 

[NWetRider]

any one else done this

I just bought a 02 WR250. I put a PWK on it before it left my garage. Motor is stock except for a Gnarly pipe. I am not the best at jetting but I ended up with a 42 pilot, JD Red needed third clip, 175. It was about 90 degrees out.

What jetting is everyone running?

 

[WLKDX]

I have the same jetting 42 pilot, 175 main, (1174K needle only because I used what I had). I just picked up a 36mm PWk and I am going to try that to get more low end. I will start with the same jetting, maybe a DDK needle.

 

[NWetRider]

Let us know how the 36 works. I took the pwk of my old bike and plan to replace it with the tmx. If it does not work right though I am just going to buy a new pwk for the Husky.

 

[scottyr]

Why not try the TMX for a bit? I would like to hear a true back to back comparison of the 2 carbs.

 

[NWetRider]

Why not try the TMX for a bit? I would like to hear a true back to back comparison of the 2 carbs.

If I had the time I would have tried it for a baseline. If I get a chance to test it I will just for a baseline. I also replaced the stock pipe with a new Gnarly (because it came with the bike) before it left the garage so I don't know if I would have to rejet the TMX to get a good baseline.

I have a feeling the PWK is a better carb though and I have a JD kit and lots of jets for it. I know replacing the TMX with a PWK is a very common modification on 01 and up Honda CR's. You can read a few hundred post about it at DNR alone. I have never once read about anyone replacing a PWK with a TMX.

Also, considering how little information there is on line about the WR250, there sure are a lot of post about jetting. This kind of confirms that the TMX is finicky on the Husky also. Maybe these are just from people with the #3 slides, I am not sure. I also get the impression that a PWK will also give better milage although I am not sure if that is true if both are jetted sharp.

 

[WLKDX]

Ended up with a DDK-3 needle #6 slide, 42 PJ, 175 MJ air screw 1 1/2. The bike ran clean to a just a touch rich in New England summer temps up to 95 degrees 50-1000 ft elev. for fall I will go up one size pilot and maybe 2 MJ for safety, we still ride when it gets 20-30.

I didn't notice a world of difference between the 38-36 MM PWK's as I thought I might. The difference between the Mikuni and the Keihin is dramatic though. I don't have to clutch as much or worry about stalling everytime I am off the gas as I did with the TMX, runs much cleaner, more linear feel with the PWK.

 

[Dirtryder]

36 Pwk

I just tried a 36PWK with 38P 160M and it ran great but kept fouling plugs. Never loaded up, idled great and started like never before, i have no Idea why. My Mukuni had a 35P and a 380M and never fouled a plug. Any ideas?