125-200cc WR 125 2008 Exhaust port.

I bought a bike to my son, a WR 125 2008 and i,ve heard that there was some adjustments that was required to get it to pull better from botttom to mid. What do i have to do?

Johnny

My son's race a pair of 2007 WR 125's and the best thing we did for more bottom is a 144 kit. Other than that, make sure the jetting is right.
We have tried the FMF pipe with stock silencer as well, but not much difference was felt by them. Stock pipe works fine and seems stronger too.
In my opinion.

Ok. it,a HGS exhaust on it now that is very dented, but i will fix that. We use 6DJ8-59 needle, 35 pilot and 410 main now and we live at sealevel at around 60F. Does that sounds right?

johnny

I think you are referring to an adjustment in the power valve linkage. I can't remember for sure if the linkage was adjusted up (which would have the powervalves open further) or if it was down. But I think it was up.

We also messed around with different springs for the power valve governor. Walt (Wallybean) made up a little kit of different springs to fine tune the timing of the power valve opening.You can get the kit through Hall's.

I also have a 2008 CR 125. I've done the following:

PV linkage adjusted (up, as I remember)
Walt's PV spring kit (but I can't remember what color springs I have in there at the moment--it was a combo to open the PV a little sooner)
Kehin 38mm carb with JD needle from Motosportz
FMF pipe with Turbine Core II spark arrester

At this stage, I still have a noticable flat spot in the mid range just before the PV opens, but it is significantly less than when stock. The Kehin helped the low end more than anything else, and the FMF pipe made the top-end hit harder. The spring kit and adjusting the linkage probably improved the mid-range flat spot the most, but they definitely didn't get rid of it.

I'll be sending my top end to Wallybean this winter to have him work his 144 magic. I truthfully believe that is the best way to fix the mid range on our 2008 and newer 125s.

I also have a neat-o Ferracci programmable ignition that I just haven't gotten around to installing. I'll try that out before I have the 144 installed.

Feel free to get the blow torch out and flame me but I think the 125 "BOG" issue is all in the jetting .

There is lots of information on this site but one could get confused if they do not know the models well.

Threre was never any talk of power valve adjustments until the 09 models so I would leave yours alone for now.

The Mikuni on your bike is the last year of the older model. The 09 and up is different so the jetting specs do not apply. Really I find the 09 and up Mikuni to be OK with the RM needle but the older one is not nearly as good as a PWK. For those that ride WFO at all times the old Minuni works fine but if you need the lower half of the throttle it is really hard to jet and once you get it right it will be wrong the next time you ride. This is more of a problem with the WR as the CR seems to be able to pull through less then perfect jetting.

So here is what I would do.

At least jet the carb you have. This is cheap to do and may be enough to make you happy, especially if you are keeping the throttle open a lot.

For a small investment get a Keihin PWK (36 or 38 mm depending on whether you want to maximzie low or top end)

If I wanted to spend more I would next get a CR ignition. I like it a lot more and the bike seems much less picky about jetting.

If I wanted more yet I would next get a factory 144 kit. Some might suggest a 144 before the CR ignition but I think a CR125 runs better then a WR144.

My bike current has a 144, CR ignition, custom power valves, cut head, FMF Fatty, Mikuni with RB design divider and low speed mods. The bike was good stock but I like to make things better and every one of these mods was worth it. My bike will smoke the last stock KTM200 I rode, it even feels like it has more bottom. There is great potential in these little motors.