New Mod?

cgreene · Mar 14, 2002

I recently saw a post on another thread that talked about a mod to a KDX that I had not heard about before. Basically -- the mod (as described by the poster) states:

" One thing I do that I have not seen mentioned is I remove the spring that is part of the powervalve assembly and is located on the left side of the motor. I actually first noticed this when my dads bike suddenly seemed to run much better then mine. We later found that this is what had happened. He called Fredette and said that is actually how he runs his bikes."

Has anyone done this mod and, if so, what results? Any potential downside to such a mod -- with respect to the engine, etc.?

BRush · Mar 14, 2002

Count me as skeptical. How about looking up the spring on www.buykawasaki.com and telling us exactly which one it is so we can evaluate its function?

cgreene · Mar 14, 2002

Mod

The quoted part of my original thread here came from a post by Kaw_Boy_5. I sent him a PM to request specifics on the mod.

Kaw_Boy_5 · Mar 14, 2002

On the left side of the motor is a bolt that threads up through the bottom that holds a spring to the powervalve. If I could post a picture I would show the exact spring I am talking about (give me tips how to if you want to see the schematic). Once removed the powervalve opens sooner. Not all may like it this way but I love it. I was shocked at first when I noticed the bolt and spring was gone but when I talked to Fredette he said he does this to all his bikes. Give it a shot. Just remove the spring and replace the bolt.

Lutz · Mar 14, 2002

Kaw_Boy_5,
I know what spring you're talking about now. The spring is actually supposed to hold a small ball bearing (at least the ball bearing is there in my '95) against the left-side mainshaft gear, and, like you said, helps to hold the powervalves in the closed (low-rpm) position.

I was confused when I took the powervalves apart on my engine and this tiny ball bearing rolled out at me...I thought I had big problems until I looked at the schematic and figured it out.

Thanks for mentioning this; every mod that can be done for free is great to know about. I'll be trying for sure it when I get my bike back together....boy-oh-boy, that 225 is going to rip!

Kaw_Boy_5 · Mar 14, 2002

Needless to say, leave out the ball bearing also.

KDX1 · Mar 14, 2002

Thanks for the clarification on this as I too am curious. I will try this on my bike now. I know what you mean when you say that the ball bearing fell out. Last summer when I pulled my top end, the same thing happened to me and I thought that I "bought the farm". I put it back in and was ripping up the trails in no time. Thanks for the mod info. :cool:

canyncarvr · Mar 14, 2002

re: mod

I wanna hear from BRush. I like the way he thinks about 'stuff'.

What do you think?

I like the idea of the detent that holds the valves in the 'de-activated' mode.

But then...the 'main' spring should do the job just as well....or not??

Looking at the 'schematic' the bolt is item# 13091 on the cylinder head/cylinder page of buykawasaki.com.

This spring isn't really adding that much pressure..it's not directly acting on the KIPS of course, but only holding the check ball against the 16085 gear. It's only the diameter of the ball as transferred to linear movement of the spring that is going to matter..it's not going to be a 'progressive' sort of thing that you'd get if the spring was actually being compressed through the entire travel of the rod.

Seems this would remove any 'snap' to the activation of the KIPS. That could be a good thing.

CDave? Even the doctor himself??

BRush · Mar 14, 2002

There must be a detent in the shaft/gear, either in the closed or open position. The first question is what's the benefit of removing the ball? Assuming the closed position, It does not seem like the ball would affect the point at which the KIPS opens. That's controlled by the centrifugal advance mechanism under the clutch cover. I think CC must be right that the main difference would be the abruptness of the movement since the detent would serve to let the whole shaft assembly "wind up" a bit when the advance shaft starts to move, before the force builds to overcome the detent spring. What, if any is the effect on power delivery? I can't imagine it would increase or decrease it, but would it smooth the transition to PV open?

The second question is what are the consequences for removing it? The Kawasaki engineers had a reason for putting it there.
Are there other forces acting that would cause the valve train to move or fatigue without the detent to hold them in place? Maybe we could get someone here who knows Jeff well (Hint, Hint Canadian Dave) to call him up and plead for a more detailed explanation?

WoodsRider · Mar 15, 2002

Originally posted by BRush
Maybe we could get someone here who knows Jeff well (Hint, Hint Canadian Dave) to call him up and plead for a more detailed explanation?

A couple years ago I lost the bolt, spring and ball on my '96 and noticed spooge dripping out of the hole. I went over to Jeff's to order parts and asked him if I had done any damage to the engine. His response was typical Jeff:

It won't do any harm. I rode the entire '98 Six-Days without it. Just put a short bolt in there with a little Loctite to stop the spooge.

He didn't mention any performance advantages and I didn't ask if there were any.

Canadian Dave · Mar 15, 2002

I've talked to Jeff about this in the past. Woodsrider's quote from Jeff is pretty much an exact quote of what Jeff told me as well, it wouldnâ€™t hurt anything.

As I understood it the idea removing the ball and spring allows the power valves to open a little sooner and make the transition in power delivery a little faster. You should be able to play with the preload on the centrifugal advancer's spring as well or change the spring to one with a lower or higher rate to affect when the transition is made and how smooth the transition will be. Give Jeff a call and I bet you dollars to donuts he's played with that as well. I know he sold a different rate spring for the 89 to 94 KDX200s at one time.

Maybe we could get someone here who knows Jeff well (Hint, Hint Canadian Dave) to call him up and plead for a more detailed explanation?

LOL You don't have to be on the inner circles with Jeff to get the full story, an honest answer etc. He's a great guy and will be more than happy to discuss KIPS valve mods with you.

David

acutemp · Mar 15, 2002

PV spring

I've talked with Jeff about this type of mod before also. He does, or did sell a spring for the 89-94 kdx's for around $ 6 or 7 dollars that would open the powervalves 400 rpm sooner than stock. When I talked to him a year or so ago about doing the same thing on my 95 he told me that I could just modify the stock spring. He never mentioned removing the spring and I think that I would give him a call before I tried it.--Dan

canyncarvr · Mar 15, 2002

So, dan....

I think that I would give him a call ...

Let us know what he says!!
:)

Kaw_Boy_5 · Mar 15, 2002

Instead of talking about this for four days, why don't you you go and remove the spring go for a ride and see if you like it.

canyncarvr · Mar 15, 2002

Why?

Instead of talking about this for four days...

1. Because some have grown past the impetuous, non-sensical approach to anything..including motorcycle modification?

2. Because if something sounds too good to be true, it probably is?

3. Because removing parts from an otherwise well operating system may well have consequences that are not intuitively obvious to the most casual observer?

4. Because being stymied to a place of inactivity by never-ending questions is as useful as jumping on some idea hatched by a scientific method that includes, 'Whar did THIS come from??'...Oh well..I'll just put it back together without it!'?

5. Because I'd prefer not to 'fix' my bike...then find it has to be 'repaired'?

6. Because 'riding day' isn't here yet..so might as well jaw-jack about it until then?

Porter · Mar 15, 2002

I only have 1 year experience with the KDX (and all of it's mechanical noises)but I think you can't ignor the obvious.The detent ball is there for a reason.The "wind-up" thought must be correct,to give the valves the snap open action.Likewise for the closed position.It's there to make sure it's in the closed position and stays in the closed position.Without even trying it, I'm sure the KIPS will work without it and most likely improve throttle response.But at what cost?The system may or may not wear out or reqiure maintanence sooner.Right now I have my cylinder off.The KIPS is cleaned and reassembled.The difference between the stock set-up and the "no ball and spring " idea is huge.Its easy to see why it would make a difference.But,you can get real close to the same feeling as the" no ball and spring " idea by using a shim washer on the bolt to reduce the tension on the ball.I have it set so the action is positive(you know it's closed) yet a smoother transition than stock.A happy medium:cool:

fatty_k · Mar 25, 2002

Well guys, I tried it on my cylinder on my bench and it does move noticably smoother with the bearing out. The whole KIPS rides a lot smoother and quicker. With the spring and bearing in, it feels a little sticky and hesitates a bit. But I think there is a way to have the spring and bearing still in and have it move justs as good. I was thinking if you cut the spring, maybe one coil, it would drop the bearing down a bit and would get it out of the way a bit or, like porter said, add another washer to the two that are already there. I would really like to ride it and see if there is any difference. I wouldn't mind a little midrange hit. (if I could get one)

fatty_k · Mar 26, 2002

I tried it with adding another washer on the bolt, and it seems to roll nice and smooth but not as freely as without the bearing. By adding another washer, it dropped the bearing so just the top part of it is exposed to the wheel. I think I have found a happy medium. It still has some friction, but I think it rolls nicer than with the bearing totally out. Now I want to ride with it and experment with it in different postions. :)

BRush · Apr 21, 2002

Since I had mine apart, I thought I'd try to post a picture.

New Mod?

cgreene

BRush

cgreene

Kaw_Boy_5

Lutz

Kaw_Boy_5

KDX1

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canyncarvr

BRush

WoodsRider

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Canadian Dave

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acutemp

canyncarvr

Kaw_Boy_5

canyncarvr

Porter

fatty_k

fatty_k

BRush

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