125-200cc Living with a TMX 38, my new WR125 setup

Wow. Sorting this new bike has been a challenge. Thanks to cafe husky for all the fine info around here.

I think I've identified the root of most of the TMX performance issues. The angle the carb is tilted is severe. too much. I'm still working on a solution for this. In the meantime...

The severe angle makes the carb VERY sensitive to float height. I think I've adjusted it 10 times now. Once I found a setting that worked, it would run out of fuel at full throttle. Drilled out the little holes in the plastic deal around the main jet and fixed that. It's still so damn sensitive that if the bike is up on a stand (leaning forward) it overflows a little.

I read the jetting database on here and mine wouldn't run worth a crap with any of those numbers.

After changing pilots from the supplied 45 down to the smallest thing I had on hand, a 30, I actually read the specs that came on the thumb drive with the bike. WR spec called for a 15 PJ. Ordered up a few all the way down to 15. Actually, I need to order something even smaller. But, 15 is so much better. I think it needs around a 12. Hard to imagine.

Went to the RM needle as suggested. Definitely better. If it weren't a 125, I'd still be working on this though. It's about a 1/2 clip rich on the needle right now. 125 doesn't spend much time in that throttle range though. Maybe that's why people don't care too much about poor idle performance?

Asked in another thread is anyone knows which YZ (or RM) intake matches this bike. I'm considering a reed spacer and machining it an angle to help the carb angle. I think just a few degrees would help a ton.

After you finally get it dialed in the weather will change and screw everything up again. Do yourself a favor and get a Lectron from Motosportz. No more hassles.

i was going to say the same thing but didnt want to go there first reply..its true tho

Firedog is right,once I switched to the lectron my days of constantly messing with the carb ended.

what size is the main you are running and the slide?

#5 slide, 400 main in it right now. Haven't totally dialed that in yet. Book says 380 main. Came with a 450 in it. bike is a 2012 WR125, new.

Dirt Dame- I don't doubt your experience in California, mine in SE Missouri is much different. I tried all the jetting and carb mods you did on the Mikuni. It would run great until it rained or the humidity/temperature changed, we have very little elevation change here like you do in the high desert. It was frustrating to say the least. The Lectron is money well spent IMHO.

I don't get that. Mine never changes. It always runs exactly the same, regardless of the weather. The RB modded one I have on my CR did make a big difference in bottom end power.

Another Lectron fan. 1 on my 300 Berg and 1 on my 165. I put it on and haven't even adjusted it yet other than idle speed screw. I might lean the needle 1/4 turn after I get the 200 pipe on it this weekend, but think the pipe might clean that up. It runs great and I will never have to adjust it for temp, altitude or humidity etc. again! Jetting is so 90's!

No i see where hes coming from dropping $ on jets is fine if you know what your doing.
But if you just want to rock up to the track an blaze away from the warm up, no stressing over lean or rich jetting a lectron is worth the extra dollars. It is alot of jets worth tho.

Hey Kelly,
Any word on the steering dampers? Please PM me.
Thanks

Hijak !!

400 main, 5 slide and 15 p !!

380 mains were in old TMX - different carb
I had old carb and that's what I ran

my 13 WR 125 ran great with a 470 main and in winter even worked well with a 490 - thats what another local guy was swearing by and it worked for me too
and that's in a sub tropical environment

Im running a 470 with the 165 now and plugs are light brown . 80 degrees - high humidity.

Not sure of your location but I suggest starting again

setting float back to standard height and going to standard needle on middle with a 30 pilot and 470 main and see how it goes ( 4 slide)

I found standard needle gives better mid to top end and didn't bog

You can always try swapping the 4 slide and stock needle with the 5 and the RM needle quickly to see any difference.

When you say the smaller pilot worked better are you talking actual rides better or just idles better when using air screw test ? To me the bigger pilots help to get bike moving down low .

there are a lot of factors at play here .

I use a 470 main and small pilot (25?) in my CR and it works great, but when I tried that on my WR165 it didn't. I found the 45p and smaller main worked best.

the extra dollars are not so much of a comparison when you have to travel a days time to find a source that sells jets and when you have 2 kids that thinks that jets are their toys you end up traveling more then one time.

beside that its the time that i don't have to spend to chase the perfect spot (or near) with the TMX

I like to ride my bike working on it I try to keep to the necessary things only

Robert-jan

What regulations? You can't be serious.

The slide is a 4.0. I was wrong about that.

Bloodline - I initially experienced the same sensitivity with the overflow and once I got it set right (there are a number of threads discussing it in great detail), changed my main and set the air screw, we were off to the races. No more fuel dumping and the bike will snap your neck when the power comes on.