125-200cc Keihin vs. Mikuni for 150

Keep us all posted out here!

I'm going to really try to make the tmxx work on the cr.
The one and only time I've ridden the bike 'the bog' was so bad I couldn't come to any sort of conclusion about the carb. I have since adjusted the PV linkage and swapped the stock exhaust for an FMF system, so I'm hoping the bog is gone and I can work on the carb. I have the stock needle and the RM needle to test with this weekend.


Once I get the tmxx carb running good I'll borrow the PWK and do some back to back comparisons. If the tmxx is as good or better then I'll spend the money on carb mods. If not, I'll probably opt for the PWK 36mm.

i have an extra 38 keihin with RB plate you could try if you want

Troffer,

What are you lacking for the 167? I have lots of stuff in the tool box.

I was going to PM you Walt for a knowlege I.V. , Pretty much need everything, I am looking at a couple of bikes this weekend. 04 cr125 and 06 cr125 , the o4 is really nice, kind of leaning that way. I was inspired by Dartyppyt's build and want to do 167 with new plastic style in old school blue and yellow

May not be the same, but I never ran my TMXX without a Power Now divider on the air box side. I liked it on my '02 and put one in when we put the carb kit in on set up.

Thanks Matt.

Good tip! When i got home last night, I worked on the old TMX with dividers on the 06. I finally dropped the clip down 5th position and it runs peffect, no stumble. My next move is to go richer pilot and move the clip back up. My son loves the torque on the bike and says it feels more like my WR250. I can't believe how this thing runs and all the torque.

I think we are going riding to test the bikes today. I might try and lower the main and pilot in the PWK since it is warming up.

Thanx!

I'm waiting on my 144 for my 08 CR125 and you guys sure have me thinking about sending my carb to RB. MattR your bonus tip is a good one. I want that work done to mine also. Heck I'm just going to pull the carb tomorrow and send it out Monday. Good info here guys, thanks.

We decided to go riding yesterday since the weather has turned around. I pulled the PWK 38 AS on my 09 to drop to a 45 pilot, since it was warmer out. I figured what the heck. I dug around my shop to find a piece of sheet metal as thick as one of my metal sawzall blades. The blade is stiff (To make a good straight cut)and I wanted to make this cut by hand. I centered where the cut was going to be made lined the edges with masking tape (The width of my blade and I also used a piece of tape to mark the depth of the cut on the blade), then a cutting I went. The cutting went fast in the aluminum, doing it by hand. I then used my inside calipers to get the inside width of the slots, Transfered it to the metal then using a die grinder, I cut the metal out. I left just a little more on the metal in order to fine grind it for a tight fit. I used my grinder and took a little off at a time until you had to tap it in with a wooden block. I then installed my slide and reached in to trace where it came down on the new divider I made. I also allowed just a little clearance so my slide won't hang up. I cut that out with my die grinder and then filed all the edges smooth. I also sanded the metal divider to make sure it was completely smooth. I just cut and made a carb divider in 15mins. I took it for a quick spin around the farm and seems to have given me a quicker throttle response and a little more bottom. We loaded the bikes up to go riding and I really like my set up in the woods. Even though, I put on the CR ignition, I am not grabbing the clutch as much as the WR. My throttle cable broke after 5 mins, by the leaded end in the throttle housing, bummer!

It was probably worth it's while because we took turns on the 06. I ended up tweeking the old TMX with carb dividers. I went up on the pilot (45) to see if I could move the clip or two higher, since we are at the 5th position down. It made things worse. So we went back to the 5th position and 40 pilot. It seemed to load up just a little in the woods. We went with the 4th position on the clip and I moved the air screw in from 1 1/2 turns to 1 1/4. Works really good, crisp torquey powerband and stopped loading up. I am really careful going up hills on this bike because it doesn't take too much to flip it. End results, he likes it better than his old RM and thinks he is faster on it in the woods.

a few weeks ago or so i spoke to Ron about the extras MattR mentions in the bonus tip... Ron said he doesn't do those low-circuit mods to the TMX, no mixture screw available either

dartyppyt, nice work tackling the divider yourself! i've seen how-tos, no thanks! hahaa

Matt, did the mixture screw adjustment with the Zip Ty equal the OEM screw? In other words, did 1.5 turns on the Zip Ty equal 1.5 turns on the OEM? I found that, sometimes, after market fuel screws on my 4T carbs didn't always match up well.

I just got back from my first ride/race on my 2010 CR 125. I have a Keihin PWK 38mm carb with the airbox side power now. After struggling to find a good set up on the Keihin carb, I got it right for my last moto. It was 55 degrees out at sea level. The final jetting was 45 pilot, 185 main, JD blue needle in position #2, air screw 1 turn out. The bike ran crisp and never bogged/fluttered the entire moto. It's amazing how much a few clips on the needle can affect the performance.

Thanks Typeone for the RB info and thank you too MattR for the Zip-Ty info. Now I don't know if I should try the stock TMX carb or just get a new PWK for my 144. Not trying to steal the thread but any suggestions?

no problem, guys. good tips on the Zip-Ty and Stealth parts, thanks!

john01, i've been going back and forth on this as well but i'm going to stick with the TMX for a while and see if i like it (RB divider + RM needle). finally got the 144 kit installed yesterday (with Walt's PVs, thanks!!) so carb mod/tune is next. i'll post how it goes.

That wouold be great and much appreciated typeone, thanks.

I did my second ride with the TMXX this weekend. The bike felt week in the morning like it was lean. One worry I have with this carb is that it will be real picky from day to day. I turned in the air screw and it was a little better. But then as the humidity and temperature increased the bike ran great. Two other people rode it and commented on how hard it pulled. I'll probably test the TMXX and PWK back to back before I sell the Keihin and put a divider in the Mikuni but so far it seems to still work.

Despite the bike running great at the end of the day my plug was white. I am running pure av gas which doesn't seem to give normal plug readings but still I know from experience that this is not normal. I am using the third clip now. When I tried the forth before it seemed good except there was a little blubber at 3/8 throttle. I think it might work with a #6 slide. That or get a half clip richer/leaner needele.