125-200cc PWK carb install...

[dirt addict]

I have read many posts, pro and con, about the keihin carb swap. I have a 38mm pwk from a previous ktm I had. It has a 5.5 slide. I put in the recommended 175 mj, 40pj (didn't have a 42/45). I had an array of keihin needles including a jd blue needle. I dropped that one in.
I was swapping in a 6.0 shock spring and had the subframe off already. So I figured as long as I was working on it, I would try putting on the pwk. So I removed the mikuni, mounted the pwk, then put the sub frame on. It went on pretty darn easily. I didn't have to fight the air boot to squeeze in the pwk, which is at least 2cm longer than the mikuni. Any way I bolted everything up , turned on the gas and bam! started the 1st kick. I just warmed it up in the yard and can't ride for a couple days, so no testing, but it sounds good....

 

[dirt addict]

here's some pics of the fit...

 

[dirt addict]

 

[wallybean]

It works but you are probably rubbing the boot on the shock spring. Just monitor it to make sure you don't start developing a crack or hole. I have had a minor rub with my original lectron and so far it isn't causing any kind issue.

 

[dirt addict]

Thanks Walt, I'll keep an eye on it.....

 

[GhostRider32]

Looks nice.

 

[rockdancer]

Yeh I could fit my 36mm keihin on to my 09 without removing sub frame

 

[Kevin_TE250]

You'll never go back to the mikuni

 

[R-J van Hulst]

You'll never go back to the mikuni

or keihin when you have a lectron

still the keihin would probably better allround then the mikuni That one changes its will every half hour depending on weather

Robert-Jan

 

[dirt addict]

As far as jetting is concerned, the recommended mj is a 175/178. If I recall the ktm 125 was in the 190's range with the same carb. Like 198 I think. Is there a difference in air flow of that much? This is on my cr125. I know I need to do some testing, but I don't want to risk burning up the piston....

 

[rockdancer]

175 should be fine - 180 at the most .

 

[shrubitup]

here's some pics of the fit...

How come the mounting tab doesn't fit into the reed block boot? I don't have a 125 but my 300 has a female notch to accept the carburetor. Personally I'd want to sink that in to avoid air leaks.

 

[dirt addict]

Inside the boot is a lip that prevents the edge of the carb from going in any further. Believe me I tried to get it in deeper. I think I saw an old post from wallybean mentioning he was going to look in to doing something about it? grind it or xacto knife maybe?

 

[Motosportz]

Inside the boot is a lip that prevents the edge of the carb from going in any further. Believe me I tried to get it in deeper. I think I saw an old post from wallybean mentioning he was going to look in to doing something about it? grind it or xacto knife maybe?

its fine as it. If it is past the hose clamp, which it is it is good to go.

 

[dirt addict]

I finally got a chance to ride the bike. The difference is noticeable. I lost most of the low end bog. It even sounds better. I kind of have the impression I may have lost a touch of over rev, but not enough to be sure. The mid throttle response is better, it starts easily, hot or cold, and feels as if the power is broader. I'm very happy with the results. And this is with an old jd blue needle I had that went to a 2004 ktm 300. The needle may be responsible for the bit of low end bog. I wish I still had the red needle. I think I liked it's response better. I am running the stock gearing too. 5.8 hours on the bike now....
Oh and I installed the 6.0 rear spring. The bike feels more balanced and turns even better...