125-200cc 125/144 Power valve Governor springs

Brad,

There are directions in the kit and unfortunately there aren't any short cuts. On the 125 you pull the pipe to access the power valve linkage cover and then you can re-install the pipe with the cover off and make all your changes quickly for all the dyno runs.

On the 250 you will have to drain your rads everytime and pull the entire case to make changes. At least there aren't very many runs to make with only 3 springs and one of them is stiffer than stock for those that wan't even more room before the hit.

Walt

OK- well Jason and I are on track for a WED evening on the dyno, excited for that. I will post results once I get them organized and proper.

In the meantime: I suspect the results of this testing will be similar to my KTM 250XC I had. Here is the dyno from that effort. It was only the middle weight spring Itested, but the KTM has an adjustable preload screw.

*NB: This my old dyno that did a decel run after the accel run to arrive at a CRANK number. The dyno we have now will render a rear wheel number. In any case, its the delta that matters.

Jason brought his bike down and we spent about 5 hrs on the dyno testing the spring combos. I discussed the results with Walt and we both agreed at the end that Jasons bike has a few mechanical issues the likely effected the results. The primary one being a bent power valve actuator axle (the one IN the lower case).

In all fairness to everyone involved we need to get another WR125/144 in my shop and test again.

Once there is another volunteer and we test again I can post the results.

Sorry to hear about the problems.

What was the best the bike put out? I would just like to know what a 144 will do. Thanks, John.

John,

It was significantly down on power. Peak hp was down about 7-8 hp from what a stock 125 will make. So it would not be a good comparison for you. Lots of issues with the bike. The previous owner tortured the poor little scoot riding and wrenching.

Walt

Ok Walt. So how much power should a stock 08 CR125 make?

My expectation of the CR125 is in the 27-28 hp at the rear wheel neighborhood and that tells you what max hp was on the 144 tested. I would expect about 10-15% more with the 144 than the 125 but we don't know that. Dyno tests I have seen of other brands 144's and 144 kits supports the 10-15% gain. With my 144 jetted correctly as it is now it definitely rips but that doesn't mean much. Shane was very curious to see if the 144 kit made it easier to loft the front wheel with the flick of the throttle. In Moab my 144 was running very rich and because it was a brand new top end I chose to leave it that way. With it now jetted well it does exactly what Shane was looking for by lofting the front by just flicking the wrist. I can attest to this because of the near catastrophic flying W I executed on my first run with it running well. Surprise!!

Walt

Well that sounds good to me Walt, thanks.

FWIW I had a 2002 YZ125 that I dyno tested after a rebuild with an OE piston and rings, -.005" off the head and it made 29 hp at the back tire and 15 lbs ft of tq, most of which was between 8K RPM and redline.

Im hoping to get a friends new KTM 150 (144) on the dyno soon, I will post results if that transpires.

I just ordered some for the new wr150. I'll let you know how they work.

I just tried the white/silver combo on the 144 and was really surprised at the difference. No hint of bog and the mid actually felt peppy. But when it came on the pipe it came on so fast that you couldn't control the wheelspin - not good on slick clay. I'm going to try the yellow/green combo tomorrow and see what that gets me. I sure love this bike!

I'm a yellow and green guy, myself--2008 CR 125.

The yellow and green combination in Kevin of Boise's 04CR 125 creates an awsome powerband. Tons of usable easy to control mid-range before the ripping top. No bog and the linkage adjusted all the way down. If it had the bottom of the 144/167 I would never mess with that motor.

Walt

I'm still on the straight Orange.

Last race I melted the powervalve linkage Power was down

I tried yellow/green yesterday and the mid flat spot came back. Today I used the white/green combo and it worked perfect. I use the 36mm pwk and stock pipe FWIW.

OK so the springs showed up. I was wondering what is the IO and FO doing as far as feeling when riding. Is the IO the start of a power band and the FO the peak power or the end of the power band? I guessing that the lowest rpm for IO is more for a woods rider?

I don't have the sheets in front of me but the first number is the RPM when the PV starts to open and the second number is the RPM when it is fully open. With the springs that open at the lower RPMs, like yellow/green, I found the bike had a flat spot at mid throttle. I went to the white/green springs and the flat spot is gone. You just need to play and figure out which combination works better for you and your bike. I'm running a 36mm PWK and stock exhaust so my setup isn't the norm.

Spring combo suggestions

Okay, after riding on the more open trails and big hill climbs on the Hatfield McCoy trails this last weekend, I believe my bog is because my PV is not opening soon enough. On some long hill climbs where I could really rev it out I found by just dropping a little in rpm the bike would seriously bog also. I ordered the the spring kit and I'm asking for any suggestions on what to try first. 2009 WR125, 38PWK, everything else stock except an FMF SA silencer.