125-200cc 125/144 Power valve Governor springs

[wallybean]

Hi guys and gals,

I have finished putting together the power valve governor spring kit. I have had the power valve governor out of my 144 so many times I think I wore out the screws on the little cover and the screw on the linkage. I have been through over 20 different springs all with different specs and have picked out the 5 that give the most variability and still close the power valve. I really wanted a spring that would open at about 42-4500 rpm but that spring is just too weak to close the power valve completely until you let the motor go completely to a steady idle. The exhaust pressure is a force I didn't count on being significant enough to effect closing but it is. This has been a labor of love and not insubstantial expense. I think the results speak for themselves and if you can't find a combination that works for you then you need to find a different motor.

I have decided that I don't want to handle the sale of the kit what so ever. The testing and putting the springs together was fun, the sale, invoicing, and shipping won't be so I defer. Hall's Cycle and Scott at Ross Rocher Sales will be the out lets and you can order the kit from either depending on your location. They will be adding margin so that they can make enough to show a profit but the kit will still be a very inexpensive item. There are 5 springs and you can run any combination of larger spring with smaller spring or the larger springs by themselves. There are 3 larger springs that fairly evenly split up the opening rpm from the weakest at 5000 rpm to the stock spring at 7900 rpm. There are 2 smaller springs that allow you to pick how much progressiveness you want and the ability to fine tune opening rpms. One smaller spring is very stiff but is about .060" smaller than the gap so it delays the full opening of the valve considerably. The other just contacts both sides at fully closed so it slightly delays opening but being softer doesn't delay fully open quite as much.

I personally am very happy with how things turned out. I really like the weakest spring combined with the shorter stiff spring. Makes the 144 a blast. BUT I AM SLOW so take it with a grain of salt. Here is data on the spring kit for you to look at:

Power Valve Governor Spring Characteristics
Large spring No Small Spring Small Spring #1 Small Spring #2

Weakest
5000 IO 5000 IO 5400 IO
5500 FO 7000 FO 6200 FO

Middle
6200 IO 6200 IO 6400 IO
6500 FO 7800 FO 7200 FO

Strongest
6900 IO 6900 IO 7200 IO
7200 FO 8200 FO 7800 FO

Stock Spring
7900 IO 7900 IO 8100 IO
8100 FO 8500 FO 8400 FO


IO = initial opening rpm
FO = fully open rpm

1 As you can see the increase in centrifugal force with rpm is a rising rate
Which reduces the gap between opening and fully open for all springs

2 Be warned that it is no fun adding the smaller springs to the stock spring

3 The rpms are an average of 10 cycles. The human element of controlling the throttle
and observing the opening of the power valve adds inaccuracies. Most all readings were
within 100 rpm either way and I feel confident that the rpms expressed are very close.
All readings were made with a laser tach with memory features
The data doesn't translate from Excel to here very well. The kit will have pictures and instructions plus a color coded spread sheat on the different springs and there opening details. The springs themselves will be color coded.

Hope this is meaningful to ones that might want it.
Walt

 

[Poopy]

Cool thread! Thats some great tech.

 

[Motosportz]

You rule. These available now?

K

 

[wallybean]

I just got this information to Jeff and Scott. I expect to hear from them tomorrow and it will only take me about a week or so to get the kits to them once they are ready.

Walt

 

[HuskyDude]

It's all Good.

 

[wallybean]

PS,

It looks like the kit will fit any 125 from 2002 to present. If everything is right with the world Husky will change the power valve for next year.

Walt

Just like now that we have found tires that truely rock(MOTO Z) they will go out of business.

 

[MattR]

Walt,

I have been following all of your PV experiments. Great work! I will be adding the spring kit to my list of goodies. It will be fun to twinker with the power deliver.

I hope Hall's will decide to stock these kits. I buy all of my parts through them, so it wil be convenient for me.

Thanks for your hard work!

 

[water racer]

Dirt Rider liked the wr125 except for the mid range bog, thought it could be cured if only there were some husky tuning experts in the US....
Maybe they should check out Cafe Husky!
GP

 

[wallybean]

With the new 144 coming down the pipe(HOPE) and more and more options to be able to make it run just the way the individual wants who could ask for more in a small bore. The rest of the bike is just sooo good. I love my 144, can you tell?!

Walt

 

[jsleeper]

This is great! I will definitely pick up a kit. Awesome job making an awesome bike even better. The WR125 has a few quirks, but they pale in comparison to the magic of the little bike. My sister is in need of a new bike and is planning on picking up a WR125 after riding my wife's. That will be Husky #3, and counting. Keep the bikes coming Husky. IMHO I think KTM and Husky are the hottest offroad bike companies right now (maybe not in terms of sales), but in terms of product innovation and fulfilling niche markets... and they seem to be doing it with 2 strokes!

Thanks Walt.

JS

 

[Vinduro]

Please fill us in on how the different spring combinations affect the low, mid and top end ? I have been away from 2 strokes for so long that the only power valve 2 stroke I have ever had was a 1986 KDX200. How would they affect say a 144cc top end or larger ? Been working on an idea.
Vinduro

 

[wallybean]

Vinduro,

The kit does not change the physical size of the ports or power valves. It just allows you to change when and how the power valves open. The spring combination I like drops the initial opening rpm from 7900 rpm to 5000 rpm but then the valves open more progressively and don't fully open until 7000 rpm. But I am not a talented rider and need all the help I can get. A more aggressive rider might want just the rpm dropped so you have 5000 rpm to handle the really slow stuff and then a Katy bar the door power band that is 6000 rpm long. This gives you a mid-range that is almost indestinguishable from the top end it happens so fast.

Hope that helps,
Walt

 

[wallybean]

I just got an e-mail from Jeff at Hall's Cycle and they are going to price the kit at $59.99. Believe me it is a good deal, if you are going to go set up an account at a large distributor and then get the wholesale price through your business account, you will still be in the kit for a minimum of $50 before shipping. They are making a little money because when I order a large enough quantity to make the first discount level they get them at that rate plus all the shipping crap. Any of you guys that are in retail know what I am trying to say because I am clueless when it comes to this stuff. I just want it available and this is the best way. (yes I couldn't sell an anti-viral drug in a flu epidemic and not go broke)

For all WR250/WR300 guys, Jeff is having me do a similar kit for those motors. It will probably be a mixture of springs that allow you to either raise or lower the opening rpm depending on what you want. Raise it to make the 300 mellower or lower it to make the 250 rip a little sooner. I will keep you posted on how it turns out. I still have my WR250 in the garage to do the testing but I am not going to ride it as it isn't mine anymore. My nephew works on the North Slope and will not be retrieving it until later this spring. I am sure that I can find someone to test it out for me.

Walt

 

[NWRider]

Who would benefit from this kit? From what I understand some of the new 125s have a bog and need to open sooner so I would think that would be one good use. Do you think any 144 might benefit since a larger motor might work better with the power valve open sooner?

I have a 06 and stock feels about right (unlike my previous WR250). If I get a 144 maybe it will be off. Ideally I would like to know what the optimum RPM is. Basically run a bike on a dyno with the power valve wired shut, then run again with it wired open, and make the power valve open where the two dyno curves cross.

 

[wallybean]

NWRider,

I agree, I wish I had access to a dyno. I can tell you that at 5000 rpm this motor in 144 form is ripping. I ran the really light spring which was opening about 4200-4500 and it was pulling hard as soon as it opened but is probably right at the bottom of the power curve. I didn't do extensive tests with this spring because it wouldn't close the pv as rpms reduced only once the motor was off or at a low idle. This made it pretty flat off idle and in the initial few thousand rpm. I made the mistake of inserting this spring and taking it riding. Not very fun riding it slowly with not much bottom. The dyno's I have seen of 144 kits that are just bore outs without porting work which is pretty much what mine is have HP and Torque curves that perfectly mirror the 125 just at about 15% more. I let the guys at work ride it before I did any work on the power valve but with the lower spring in the kit and one came back amazed and the other who has an 09 KTM 250 xc-wf said it ran just like his 250. Same bottom, slight flat spot, and then a ton of rip.

Walt

 

[Vinduro]

Vinduro,

The kit does not change the physical size of the ports or power valves. It just allows you to change when and how the power valves open. The spring combination I like drops the initial opening rpm from 7900 rpm to 5000 rpm but then the valves open more progressively and don't fully open until 7000 rpm. But I am not a talented rider and need all the help I can get. A more aggressive rider might want just the rpm dropped so you have 5000 rpm to handle the really slow stuff and then a Katy bar the door power band that is 6000 rpm long. This gives you a mid-range that is almost indestinguishable from the top end it happens so fast.

Hope that helps,
Walt

Walt, I understand that it doesn't change the ports. What I don't understand what you are gaining or trying to gain by wanting the powervalve open sooner ? What happens if it opens later ? I am a fast enough rider. Former ISDT / ISDE rider and Nat'l Enduro rider (still). Just a bit older these days. I have always liked a smooth torquey midrange with decent low end and top end. I like good pull the front end up over log power but not too much uncontrolled wheelspin. Discribe the power characteristics with each setup and RPM range .
Dwight

 

[jsleeper]

Walt, I understand that it doesn't change the ports. What I don't understand what you are gaining or trying to gain by wanting the powervalve open sooner ? What happens if it opens later ? I am a fast enough rider. Former ISDT / ISDE rider and Nat'l Enduro rider (still). Just a bit older these days. I have always liked a smooth torquey midrange with decent low end and top end. I like good pull the front end up over log power but not too much uncontrolled wheelspin. Discribe the power characteristics with each setup and RPM range .
Dwight

I think the main motivation for the experimentation with the springs was to 1) get rid of the mid-range bog, and 2) make the transition from bottom to top more progressive. As an owner of a WR125, I suffered from the same problems many have had, which is a bike that chugs great, bogs in the middle, then screams on top. However, the transition is horrible, and seems to range from annoying on some bikes (mine) to un-ridable on others (Walt's).

On my bike, it was possible to ride it fast keeping the PV open. But that is only good for slamming through the gears. As soon as the PV closed the bike would not accelerate in the higher gears.

As Walt theorized, the PV may be sealing too tight, causing the bog. I can confirm that the bog felt like a banana was in the tailpipe. Then you downshift (opening the PV) and the bike takes off. By putting in different springs that open the PV sooner and/or keep it slightly open from bottom to mid, it seems to cure the bog.

I think it was some kind of fortunate (or unfortunate from Walt's point of view) coincidence that Walt got a bike with a serious bog...because he had the drive to cure the bog vs. getting rid of the bike. A lot of other people are able to cure the bog with a simple needle adjustment and/or a bit of grinding on the stock PV spring.

However, even though the bog on my WR125 is virtually gone, I will be buying the spring kit just to have more options, and to help fine tune the bike for my wife's needs.

JS

 

[wallybean]

Vinduro,

JS hit it on the head. If my 125 had run like many others I probably woudn't have messed with it. The springs do allow you to limit the bog on even my grand canyon by letting the bike rip. It does make it a little harder to ride smoothly in tight gnarly stuff so for the talent impaired like me I wanted to have the pv open only slightly to get rid of the bog and give me that torquey mid-range you are talking about and still keep the wide open top end pretty much where it is. I guess what the spring kit does is allow you to tailor your powerband to what you need. For the many guys that have 125's that run exactly like they want, it probably has no value, but if you like to tinker it can be fun and you might find something that you didn't know you had. Changing the pv is so easy on the 125 that it can be done by even the least mechanically inclined among us. If that is worth $60 is certainly up to the individual, its not like there aren't a lot of goodies that are worth investing in. Suspension tweaking to individual needs is certainly where most all of us would benefit the most.

I will be very interested to see if some of the guys that have the new Husky 144 kit or have opted for the low to mid-range detailing option from EG could run theirs with the pv wired open. While you can on mine it doesn't do well below 4000 rpm. When I spent my week and a half riding in south eastern Nevada and then in North Western Arizona, I was using the spring that is the weakest large spring in the kit by itself. I was riding from 4000 to 6000' in Nevada and 1000 to 4000 in Arizona. The Arizona riding was true desert stuff, Washes, rocks, rock faces and ledges, washes with whoops, and did I mention rocks. This combination ate this terain for lunch, great fun. I am jealous of all you guys that ride at sea level and get that extra 10% that I didn't even know the motor had. In Nevada it was all fairly dense scrub cedar with some washes mixed in. Lots of 1st thru 3rd gear slolum running up and down the hills. I spent most of the time running in the bottom end and it worked well and pulled my fat ass up almost anything. The transition to the pv opening in these areas is a bit abrupt just as you said and caught me out a few times but the Husky 125 is so flawless that it made the recovery despite me.

Since I have been home and worked further on the different springs, I have found that combination that will be great in my neck of the woods. Nice low end, nice mid, and then a ripping top if you need it. It is nothing for me to start at 4500' quickly get to 7000' and then spend the rest of the ride bouncing through the downfall and tight stuff from 7000' to 9000'. Rarely getting out of 4th gear. This is why I pursued the spring kit. The nice thing about the kit is you can take the stock spring and add an additional inner spring and raise the opening rpm like you talked about. If you were to get your 125 bored to a 167 or even a 175 if that is possible this might be what you want. I think I smell a resleeve to a 175 with a reduction in port size and reshaping of the pv's and exhaust port for low and mid. There certainly is room to sleeve and retain the exhaust valves albeit they will only raise the exhaust port a fairly conservative amount. Might not be the most efficient over square design but it might be a trail riding phenom.

HMMMM, my spare time next winter just got reserved. All I need is the Husky 144 kit from Kelly when I royally screw up my existing cylinder and then I would be good to go. There is a re-sleeve place a few hundred miles west of me. HMMMMM

Sorry for the long winded blather,
Walt

 

[Vinduro]

I appreciate the explanation. Sounds like something most of us should have, if we have a 125. Do you think we would need to go to next step heavier spring with a big bore kit ?
DR

 

[twowheels]

Way to Go Wally

Hey, I don't even own a WR/CR125 and I couldn't stop following this post!

The work that went into this "little spring discovery" is phenomenal. I hope you're getting a dollar or five off of each kit.

It may be interesting to see what a dyno could tell you about changes in the torque curve, but thats about all, because not many of us ride dynos anyway.

Keep tuning Wally - the (Husky) world is better for it.