All 2st About the Mikuni/Keihin swap:

What seems to be the best setup for a 144 / 150cc ? A 36mm or 38mm. Looks like to me that a 36mm would give better response and low end. Jetting ?

I am running the 36 and it runs great - very clean on the low end. I seem to have lost a bit on the top but I rarely ride there anyway. I haven't rode a 144 with the PWK 38 so I can't compare.

09 WR125 with OEM 144 kit
Stock pipe w/FMF Turbinecore II
PWK 36, 165 main, 45 pilot and CEL-4

Sounds OK. I am a short shifter anyway. Been talking with Hall's about a WR150.
Just thinking about the mods needed.

I had just pushed my PWK in and made it work, or so I thought. I'm realizing that because of the greater length, it is very difficult, if not impossible to get it lined up straight in the boot to the reed valve. Today, I found a bit of dirt.:jawdrop: After just having to do an early top end job because of dirt, I decided to put my Mikuni back in until I figured something better out. What are people doing about the extra length to get a good fit?

Simplest solution is to tip up subframe and airbox, install carb in intake and tip subframe and air box back down straight onto carb. I did it this way when I first installed my PWK, but after hearing everyone say they could get it squeezed in there, I tried it on a jetting change. I finally got it in there, but next time... I'm tiping up the subframe! It doesn't take that long to do and I sleep better knowing I didn't get crap in the engine wrestling with the carb.

Has anyone ridden a bike with a 36mm back to back with a 38mm? Im also thinking a 36mm would be the way to go if it is better off the bottom

First time I did it was without an extra helping hand. It was hard, but got in ok. when I needed to change the pilot, I had to take it off again. It was out on the trial, and was actually easier as I had help from a friend holding the airboot back when I stuck it on the engine side first and then we both pulled the boot onto the rear side of the carb.
Easiest bike to work on.

I never had a problem, but I turned mine down one snowy day to match closer to the stock carb. It's only about 3mm longer now and the throat shape matches the stocker much closer. So, it's really easy to mount now.

Any good machinist could do it in a few minutes.

Get the rubber boot wet and the PWK will slide right in without a fight. That's what I do on my 300 and works a treat.

I use silicone spray on the rubber to make them slippery when i push the carb in

Johnny

Johnny,
haven't had a chance to get an EEL, but I tried the N3EJ (06' yz250) needle again in the 2nd clip and liked what I felt. Quite a bit more aggressive off idle and into the mid than the CEK or CEL, which made getting into the power much less abrupt.

I was going to try it with a 42 pilot, but my chain broke before I could get back to camp and make the change.

I wonder what Keihin part number the N3EJ would translate to. It might not be too far off the EEL from your description.

Hi PC! Well, there is no translation sheet for those codes to the Keihin ones. I guess the only way to know the difference is to use a gauge and compare the needles. You can use a gauge and put both needles next to eachother and very smoothly open the gauge and see which needle drops down the longest way first and at which position. Then you know where it´s richer then the other one. I did this when i compared my needles. Measured every 5mm and wrote it down. I know i´m a little weird!

Johnny

I have both a 38mm and 36mm for my WR250. Haven't had a chance to get a back to back comparison yet.

or you can use thet jd jetting spreadsheet to compare them.
A few of the newest needles aren't in jd's spreadsheet, but most of them are.

pretty sure the n3ej is a multi-taper needle. There's a pinned thread in the ktmtalk jetting forum regarding needle codes that might shed some light on the topic also.

The N3EJ is a dual taper needle where the standard PWK needles are single taper. Playing with the JD Jetting Guide I was able to come close with a CCN with it being a tad richer 1/8 to 1/4 throttle and then a tad richer from there up. The EEL is leaner from 1/8 to 1/2 throttle and then gets quite a bit richer by full throttle. The CCN has a smaller diameter and less taper. Of course this is all on paper and the real world applications don't always match.

Ok, didn´t know about the JD needlesheet! My conclusion is that my bike likes needles with quite much taper. The EEL is the best of Keihin´s needles i have tried, and a quite big main seems to work fine too, especially with those needles. The CEL needle has two steps less taper compared to the EEL for those who didn´t know

Johnny:sweden:

Johnny you sir are the Walt for the 300's. If and when I get one I will be following your lead. Thanks for all your testing and reporting.

Thanx Norman

Hi and thanx, I was starting to think along similar lines but had not worked with it yet. You can certainly squeeze it in, but getting it perfectly straight and therefore properly sealed is what I find difficult. I haven't ridden the bike since Sunday. I lost my kick starter during a hare scramble! The good news was that Hall's had one in stock. The bad news is that it wasn't cheap! You can bet the new one wil be sure to get get locktite!

Man David I should have told you to locktite that sucker. My son's came loose on his TC250 but we found it on the MX track.

I lost the nut on my kickstarter one day 20 miles out in the mountains. Luckily for me it hung in there (by a thread) until I went to start the bike and I kicked it straight off onto the ground.

I feel your pain. Kick starters are not cheap!


While we're on the topic dont forget to occasionally break it down, clean it and grease it. Otherwise the vibration and grit will bore out the hole and make it loose and sloppy.