KIPS Governor Mod

[Jeb]

‘Been wanting to change WHEN my powervalve opens up. The mods in the bike have gone a long way to help with the power and top end, but I’d like the power valve to open SOONER. Two ways I see relatively easily making this happen . . .

. . . decrease the spring rate (or preload) of the spring against which the governor must push. Less force to push against and the governor should open up at lower RPMs. In fact, the proportionality is the drop of RPMs will be the square root of the drop in force required to compress the spring.

. . . increase the weight of the 4 governor balls to increase the force that the governor applies. More mass means more force (directly related) so the governor should open at lower RPMs in this case as well. Same proportionality!

I don't expect the results to be staggering but I SHOULD detect some difference.

Here are some estimations:
*10% increase in ball weight or decrease in spring rate = roughly a 5% decrease in RPMs
*15% increase in ball weight or decrease in spring rate = roughly a 8% decrease in RPMs
*20% increase in ball weight or decrease in spring rate = roughly an 11% decrease in RPMs

So I got ahold of springs of different rates/sizes and some brass balls at or near 5/16” (size of the OEMs) and removed the governor assy to see how this might work . . .

Go HERE to see more details/pics.

The 11/32” brass balls didn’t fit so I went with the 5/16” brass balls. This provides roughly a 10% increase in mass so I should see roughly a 300 RPM drop (if I'm right about how the governor works).

I went with a compression spring made by Smalley Springs that had a very slightly lower spring rate (as measured crudely by me) and was about 2mm shorter. Overall I’m estimating that I’ll get another 100-200 RPM drop from the differences in the spring.

So, if I'm reasonably right, I oughta' see the KIPS move at 5,400-5,600 RPMs.

So I need to test! I want to monitor the RPMs while I roll the throttle and watch the KIPS open up. I'll update later, probably have to wait 'till next week. Then, of course, seat-o-the-pants test, hopefully soon.

[canyncarvr]

Curious...have you modified the spring on the detent side (LH) of the main shaft?

..the proportionality is the drop of RPMs will be the square root of the drop in force required to compress the spring.

You might want to reconsider the $e%%y talk..you'll have some Kanuck's all over your arse.

An increase in ball size (mass) will increase the load on the device..I'm sure you considered that. Is the retainer up to the additional load? Talking about squares of things...that's what's going to happen to the force those balls exert on their restraints when the speed goes up.

I JUST read within the past few weeks of spring replacements for the KIPS..heavens knows I don't recall where that was.....

What do you use for a tach? You got one'a those fancy odo/speedo/last lunch break things?

This is going to be fun!

**
Excellent notation job!!! Of course, I loved the HiDef pics 'specially (my camera doesn't do macro worth a damne).

Why brass? Available? You mentioned a diameter change of .006" or so..that was a ball diameter I presume..was it larger or lesser (and still fit)? I'd wonder about the hardness of brass (not) in that applicationoid.

What is the movement of the sprung assy? Just curious 'bout that..I've not measured it. Smaller balls still allow for the max movement of the assy? At some point, too small a diameter (fit or not) won't 'push' as far. While you're noticing KIPS activation points, make sure the main shaft is moving as FAR is it needs to.

A BTW...but I notice your outside clutch plate is 'one off' the pack. Are you still running the OEM plates..not the wider XR plates? ..or, do you use an OEM plate in the last position only to accommodate the conical spring and seat (that's my setup)?

What's the difference in weight between OEM and brass?

Great stuff!!

[Jeb]

LH detent ball - If you're referring to the little spring that compresses the detent ball, I've left that alone for now. As I understand it (and this is my own logic if that's what it can be called), this little spring provides sort of a "break-away" force to make more of a sudden KIPS movement. I can tell you that this small spring pales in comparison to the force required to move the governor spring. THAT spring is STOUT. Nonetheless, that little detent spring IS part of the whole equation.

Is the retainer up to the additional load? Talking about squares of things...that's what's going to happen to the force those balls exert on their restraints when the speed goes up. - Great questions. Unless Kawasaki engineers designed that thing so that it barely held things in with the OEM balls, I'd say it'll be OK given that the total mass has changed by a relatively small amount with a change in resultant force against the retainer by about 5%.

ball size, weight, material, etc - I chose balls of the same size but different material, from a 5/16" steel to a 5/16" brass. I'm not sure of the exact weight of the OEM balls, but they're listed as "steel" and they look to be of the stainless variety. And the densities of most common stainless materials aren't that different, with a specific gravity (SG) range of 7.8-8.0. The brass balls are readily available and have an SG of about 8.6. The brass indeed is more malleable with yield and tensile strengths about 1/4 that of, say, chrome steel. The good news is that means they'll deform a little at worst but shouldn't fall apart. Point well-made, though; I need to do a mid-year checkup to look other things over anyway and that'll be something worth checking.

The 0.006" measurement was how much extra wiggle-room both the oem steel and the brass ball have. Meaning that there's not much room to use a bigger ball if one wanted a bigger, i.e. heavier ball.

. . . movement of the sprung assy? - 'Rougly 6-7mm if I remember correctly. And as it turns out, the movement stops because it "bottoms out" without the spring being fully compressed (I checked this with the OEM and new spring), and at that point the balls are still enslaved by the retainer! The retainer comes into contact with the inside of the plastic gear.

What do you use for a tach? - nothing yet but I need to find something by next weekend. What do you recommend?

A BTW...but I notice your outside clutch plate is 'one off' the pack. Are you still running the OEM plates..not the wider XR plates? ..or, do you use an OEM plate in the last position only to accommodate the conical spring and seat (that's my setup)? - I need to learn more! I have the stock setup in makeup and assembly. What's the advantage of the XR plates?

[Ondatrail]

I wonder how adjustible power valves work... Looked around and I would think if you found a way to adjust the springs tension it would work. Easier said then done eh?

[Jeb]

Yeah, what I'm doing is what you've described in a way . . . but there's no way to just adjust the tension on the spring like you can do with other bikes.

[Jeb]

So here's an update.

Even though it's a little chilly I'm itching to ride. Got her warmed up pretty good. Took off the KIPS cover on the LH side to watch movement. Don't have a RPM meter yet, but I juiced it several times. There's NO doubt that the KIPS actuates sooner although I'm guessing to say how much. I was anticipating having to use something that measures RPM to be able to really tell because I estimated 300-500 RPM lower but this is more like 1,000 because you can see/hear it. And, FWIW, it STAYS open LONGER best I can remember how it was before, good or bad as that may be. I believe where I was mistaken on my prediction is how much effect a lighter preload on the different governor spring is making.

I couldn't resist using the service road behind the house to get a feel for the change. I rode for maybe 15 minutes (left plenty of time to hide from the cops if they were called ).

I have a little hitch/burble moving up from low RPMs but I think that's jetting. I think it will resolve itself when it warms up, maybe a needle change perhaps. It's pretty mild and doesn't happen every time and seemed to lessen as I rode more.

When rolling the throttle, there's an unmistakeable "pickup" just above midrange - you can feel the front end lightening as the RPMS get higher. Not too abrupt of a change from before but noticeable. As I tried different throttle openings and getting more aggressive with opening it, I can sense more power delivery at lower RPMs as I had hoped for.

Frankly, I'm getting reacquainted with my bike having been away from riding since last September with the knee surgery. I think I've forgotten how good Ron's mods are. But, best I can tell I've got a distinctive edge now . . . I do feel power coming on when it didn't used to as I remember it.

I need to do more riding, like, LOTS more riding!!

The biggest differences:
1. There's more of a hit sooner. Two stroke glory. Actually, to put it in the correct perspective, it's more like a mid-RPM surge. I personally LOVE that. A LOT!!
2. When I short shifted, like 3rd into 4th, then would take a little jab at the clutch, just a little, to spin the motor up quicker, SURPRISE!. I used to have to make a more deliberate clutch movement for the same effect. I think the little jab is now enough to get the powervalve opened and hence the effect.
3. The wheelspin comes on quicker. A portion of the service road is gravel so I took advantage of it for testing purposes. Seems like more of it but that may be because of when it's happening.

I really need to ride more and fool around with the jetting to get a really good feel for it but I think I like it!

[canyncarvr]

Something to keep in mind: The timing retard 'programmed' into the sparky box is intended to coincide with the exhaust timing change (KIPS). How close the two actually are isn't something I know. It's likely (considering the kawi engineers did some sort of decent job) the two aren't the 'same' any more.

Re: Short shifts and clutch jebs....

I'm sure you have it listed..but what needle are you running, and what clip? Don't forget (like I know you wouldn't) to mess with that part when you go after this particular bobble.

Have fun!

[Jeb]

Something to keep in mind: The timing retard 'programmed' into the sparky box is intended to coincide with the exhaust timing change (KIPS). How close the two actually are isn't something I know. It's likely (considering the kawi engineers did some sort of decent job) the two aren't the 'same' any more.

Re: Short shifts and clutch jebs....

I'm sure you have it listed..but what needle are you running, and what clip? Don't forget (like I know you wouldn't) to mess with that part when you go after this particular bobble.

Have fun!

Yeah, I'm sorta studying on the whole timing thing. I know you posted a thread on a fellow that sorted this out. It was for an "older" model KDX but the idea is the same. I'm wondering how the timing on mine being retarded to favor the top end changes things along these lines . . . I'd like to fiddle some more with that even if it's a PITA.

I'm running the CEK that Mr. Black installed, #3 position even though my bike profile says #4. When us Kentuckians get together for some jetting here shortly, I'm going try a bunch of clip positions to see. I only moved it between #3 and #4. Maybe some cool surprises!

Gotta try a DEK sometime as well. Time to order one. Any other particular suggestions that might be fun? I don't mind ending up with a needle or two that has limited use on the chance that I could find some other thrilling stuff . . .

I wanna try some toluene too. Throttle response has been very good since the Ron's mods, particularly sharp after the race gas head. Just the same, I'd like to see if a little toluene does anything . . .

which reminds me - I WAS running straight C12 on my thrill ride yesterday!

Yep, I need an entire day just to fiddle with settings.

[canyncarvr]

The spec sheet says 21º@6000RPM. That leaves out a good bit..like what the curve STARTS at, and what it drops to when the timing cap is saturated.

Re: Particular needles..

The DEK/CEK work well..depending on the flavor of ride you want. I was suggesting changing the clip OF your favorite needle to see how that effects the bobble.

I don't know that toluene would have as great as effect on 'real' fuel as it does the junk out of the pump down the street. Won't hurt to try it.

Cheers!


Don't break anything!

[fuzzy]

Cool!

[hart125]

I know I talked to jeff fredette about this quite a while ago and I also remember some previous threads on messing with the power valve. that might be over in the dirtrider.net site though?? anyway the point was not to mess with it.. its been setup from the factory, you want to get a smooth transition from rpm ranges. if you start messing with the power valve you get more of a sudden transition like the older mx bikes. Maybe more power over a wider range but the transition will be less predictable.

[Jeb]

I read through some of those threads and, best I can tell, the "mod" in that case was to remove the detent ball/spring on the LH side of the main valve actuation shaft (the shaft that traverses from left to right that controls the powervalves and the subvalves). That makes the movement of the powervalve more gradual or "analog" so to speak, removing the more discrete movement the detent ball provides at around 6k RPM. Depending on how you apply throttle and how the engine responds, with the dentent ball/spring removed you could very well end up with an unpredictable power valve actuation.

In this case, I've changed when the discrete movement happens by modifying when the governor provides enough force to start the actuation. Since I've retained the detent ball/spring I should get as predictable an actuation as I had before, just at a different RPM

All that said, maximizing the benefit will depend on a bunch of things. There's probably an optimum setting of which I really am not sure of yet. And the benefit isn't exactly staggering or anything, just a way to make a great bike a little bit better . . . at least for me and in my own kind of way

[Indawoods]

Now... make it adjustable on the fly!

[Jeb]

That would be cool, Inda . . . then those orang-ish high-dollar rigs wouldn't have anything on us!

[muddertrucker]

Except a high price.

[Cturbo]

On a KTM 250 exc, changing the power valve spring to open sooner will make the hit less noticeable. Remember that the high speed porting needs RPM's in order to work to it's potential.

[Jeb]

. . . Remember that the high speed porting needs RPM's in order to work to it's potential.

What do you mean by "high speed porting needs RPMs in order to work to it's potential"? What is high speed porting? The speed of what, the bike? And at what RPM does is this potential reached on a 220 . . . and is it different than a 250exc?

I woulda' thought the way to change the "temperament" of a given bike - temperament being the hit, where it tends to come on and how hard - would be different for different bikes, based on a the way the motor is built/tuned. What I get from the KTM guys is that there's a different effect not only on what you do to the spring (different rate vs. different tension) for a given bike but between different bikes, of the same OR different displacements.

Another example, the RM85 (the only 85 with a power valve I think***) is reputed to gain a bunch of midrange by installing an aftermarket device that BOTH opens the valve sooner AND slower (as I understand it).

***EDIT 4/20 - This ends up not being true, other 85s have powervalves as well, just a BTW ***

The feedback seems to differ enough to make me believe that you can't draw the same conclusions from bike-to-bike on what happens when you fiddle with the power valve.

Which is why I went to fiddlin'.

I notice the power has shifted down, not lessened. My first impression is that it's a little more abrupt. Which may or may not be the case on a stock KDX220. Or maybe less on a KDX200 or, who knows, maybe MORE on a KDX200.

I do have enough of the brass balls if one of you "two-hunny" owners wanna' give it a whirl!!

[Jeb]

Got a chance to check things out to some degree . . .

took the kiddo out to an indoor mx track called Cowtown (a converted rodeo if you can believe that). Anyway, it's pretty supercross-style which isn't exactly KDX territory but a chance for some seat time ('bout 4-5 hours total, probably rode 75% of the time, very few riders there). It did give me a chance to test the "boom", coming out of some of the corners with enough acceleration to get some air off of the next jump or tabletop.

Sort of humid (raining) with temps in the 50s somewhere . . .

The bike ran great. Good snap; excellent throttle response. MORE POWER AT LOWER RPMS. It actually took some getting used to because when the RPMS spin up a bit here it comes.

Then I dropped the clip on the CEK to #4. I could NOT believe how much difference that made. Just to be sure I returned it to #3 . . . yep, that much different. I would not be inclined to run the bike in slippery conditions with the clip in the #4 position on this CEK. Pulls steady from really down low, gets snappy from about 3k RPMs and up. Above 6k or so it just pulls and pulls. Around 4-5k things get really spunky, I kid you not. REALLY noticeable on the whoops - kinda nerve-wracking actually. Or if I landed from a jump with enough speed so the RPMS were in THAT range and applied throttle - HOLD ON.

I kept my knees buried in the rad covers and had a stop a few times to rest my freakin' arms. It put a smile on my face.

I'm not going back to the stock governor setup - no way.

And I never really got to play with the A/S although I made a few small changes. I just wanted to keep things as is (or is that "as was"?)

Here's my setup: RB carb with CEK @ #4; 148MJ, 38PJ; A/S is about 2&1/8; RB modded head, shaped for race gas; running 2 parts C12 to 1 part premium pump with Amsoil Interceptor at 32:1; KIPS governor modified to open up somewhere around 4,500-5,000 RPMs; FMF rev, PC Type 296 S/A.

Almost forgot: this is also the first time I've put my suspension changes to more of a test. With the stiffer rear spring that Wibby sent me and the gold valves up front the balance felt really good. What was most impressive about the gold valves was that I changed rebound twice and the change it made was very noticeable in the whoops (one change felt worse, one felt better). Point being that a 4-click change in either direction made a big difference. Never touched the compression (never got there).

OK, I'll stop, but I had to recount the events. I'm lovin' it!!

[fuzzy]

Good report!

[canyncarvr]

Thanks for the write-up!

Man...I haven't been riding in about 24 hours. It's time to do summa that.........