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I think the KDX is just fine down low and up high and don't see where I tried to imply otherwise. GS said they lacked hit and - compared to a competition-level machine - they DO. And that's just fine . . . as long as you're not looking for that kinda snap.

Reading what you guys have written could make one assume that the KDX does not run well up top, which it does, at least the 200 does

And that is what the OP is trying to sort out


Just my take on it

I happily trade UNBELIEVABLE tractor GRUNT for that silly little wheel-spinnin' 'hit'.

All I wanted to imply was that if you're expecting the hit of an mx bike, it won't be there, but that you'll notice that the other guys, with their 'hit' bikes aren't leaving you in the dust AT ALL!

Just wanted to make sure he understood that is a (great) characteristic of the KDX.

I just wanted to make sure the guy does not think that KDX's don't run up top

His bike is not right, just don't want him to think they all run like that

A couple new findings. I stuck a new plug in it. Took it for a ride to get it up to temp for the compression test. It ran a bit better, reaching the higher revs a bit more cleanly. The tiny headlight worked better than expected.

Just for fun I looked at the LH kips gear motion. It was again getting held up (stuck closed) at the point of the detent ball.

Removed the plug, (black wet insulator tip) did the ole compression test: I couldn't kick the needle past 120#. That's kind of the low normal isn't it?

Now I see that I need to tear it down regardless to clean the KIPS, so I guess its time to do the top end rebuild as well. Then jetting.

Is it possible that the bike would actually run better without the kips if the topend is weak?

Can't wait to get her sorted

Compression: 120# is a bit on the low side, but depends on many factors.....such as each of your leg muscles! How does it feel when you move it through the range slowly?

You seem quite ready to do her up, so guess it doesn't need to be really know, those parts on their way out anyway.

Great idea to run through the whole KIPS system....take photos and remember that there are...
1) ONE NUT/THREAD THAT NEEDS TO BE TURNED IN REVERSE OF THE NORMAL DIRECTION.

2) THE KIPS ACTUATOR SHAFT MUST BE HELD WITH A WRENCH OR GOOD VICE-GRIPS PROPERLY OR YOU WILL BE REALLY SORRY.

Take pics as you go and watch for a check ball and spring, likely gummed up and lying in wait to drop onto the floor when you least expect it.

There is lots of info hereabouts, just search BEFORE you start, will save expensive mistakes.

Here's a good overview for a top-end job.

http://justkdx.dirtrider.net/bakimseytopend.html

Very good overview, Grump

GS wrote:People here are the best, anywhere. The BEST!

Sounds like you're maybe a little spoiled by displacement!! But the KDX is worth gettin right, she can really keep up and you can watch the other riders shake their collective heads......which for some strange reason REALLY makes me smile.
Guess I like being the underdog.....with others looking down attcha, until they get a lil green surprise! Just adds to the FUN factor.

I could not agree with you more GS. My neighbor bought a new Yamaha YZF 400 and my little KDX 200 (stock) would blow his mind everywhere we rode!

Dentvet - do you have a manual? The clips and posts are great for help but those are supplementary to a manual. One place to find a GREAT manual that's available immediately that Indawoods provided for us is the cyclepedia.com manual - click the "KDX Manual Online" to join - yearly fee is <$20, well worth the cost. Great descriptions, great pictures.

If the governor rod cannot hold up to the force necessary (considering the system to be working) to manually activate it using that LH access, it will not hold up to the force necessary to activate the KIPS itself" . . .

Jeb wrote:I gotta disagree.

Then we agree on something, 'cuz I disagree with you.

Not really...I just think we be not talkin' 'bout the same thing.

Jeb wrote:The forces against what the governor rod must work when the KIPS governor is activating the rod (the ball/detent) is much less than the forces the rod must work against when working against that spring in the KIPS governor. Remove the claw and you can twist the rod that activates the power valve and sub valves much more easier than you can compress the governor spring.

It should be impossible for me to disagree with what I don't understand (can't say as I follow the above), but, I do.

I think you're referring to an issue of gearing, the multiplication and division thereof. Obviously ratios matter...that's why cars have differentials (the term 'differential' in this case having nothing to do with what the word actually means, but referring to the final gear reduction in that assembly that real cars have). It takes more force to turn the driveline and make the car move than it does to turn the wheel and make the driveline move. Try it with your hands sometime.

But...that has nothing to do with what I was saying.

If the detent ball/spring takes 'X' force to get 'undetented', that same 'X' force at the ball will be required regardless of which end of the gearing sequence it comes from. Yes. You may have to turn the following gear (under the LH cover) with more force than what is required from the other side, but it can handle it..and still, the same amount of force will be required...at the ball.

I can push a pine needle around with a 2x4 for a long time and not hurt the pine needle, but if I try to push the 2x4 around with the pine needle...something is going to break, and it ain't the 2x4.

..which, again, I think is what you were saying...and not what I was saying.

Generally, it's always good to drive the drive and have the driven driven..don't do it backwards and have the driven drive the drive. Still, KIPS can handle it (manual activation via the LH slotted cover).

The flat on the governor shaft is to prevent damage from excessive force that will be applied during the removal of that nut. The governer will be driven PAST its normal limit..something that it is impossible for it to do by itself...from the 'normal' direction.

Wrench on the nut under the LH cover past its normal limit and you will break something, too....a tooth off the gear. That happens on a regular basis.

Again...not what I was talking about.

I forgot to thank kawagumby for pointing me towards this fine site.

I haven't taken one apart but i've looked at the exploded diagram regarding the kips. Here's my understanding of the kips mechanism.

The gears and shafts within the cylinder open and close the exhaust port valves. The geartrain is held in the closed position by a return spring of some sort (different from the detent ball in the lh cover)

The geartrain in the head is turned by the governor shaft which extends into the area of the rh crankshaft. The gov shaft is twisted when the bike reaches 6000 rpm. The twisting is caused by narrowing of the gap in which the flat end of the gov shaft resides. The flat end is at an angle with respect to the axis of the crank. As rpms rise, the crank gov compresses two plates towards eachother, which pinches the end of the gov shaft, making it twist through a cam action. The two plates or discs are held apart by a spring. Is this anywhere close to being accurate?

I know its wordy and the only reason I typed it was to learn more about the bike. It also might make clear why you can tun the assembly by hand and not break stuff. If the shafts and valves aren't frozen, you are merely overcoming return springs and detent balls and sludge friction, right?

If the kips is completely frozen with sludge, I bet the governor plates are just pinching in vain, not being able twist the shaft. Clean things up and everything works again, right?

Set me straight, please

Re: 'The twisting is caused by narrowing of the gap in which the flat end of the gov shaft resides.'

It's a pin attached to the shaft..not a flat..that provides the axis offset:

Here's a pic of a bent/broken one (shaft not supported..and the rider didn't know it was a LHT nut)



..and with the centrifigal assy (again,not a working one):



Re: 'Set me straight, please..'

Unlike the pictured shaft...no straightening required.

There is a big difference between the power of a 600CC anything and the KDX.

Get the KDX running nice and you'll give that CRF450 a run for its money in the tight stuff.

[hijack] We met a couple of CRF4s this weekend..heading UP a track we have only gone DOWN. One of 'em hit the 6' vertical entry chute..went over the top with his front wheel barely clearing the ground (don't know how he did that..like I said..it was mostly vertical with an oververtical lip a couple feet from the top)..hit the ruts-n-roots on top and flew up the hill. Yah....it's steep!!

The second guy didn't have quite that good-a-luck. We had to give him a hand. He got over the bank OK the two/three times he tried it..but got good-n-stuck directly after.

Did I say it was steep? With two of us (me'n the wookie) pushing down on the back of his bike, he STILL couldn't get going. And THAT was in a primo soil spot with no roots/ruts.

You had to get it like the first guy..hit the vertical fast enough to get up, not so fast as to loop it, but fast/smooth enough to have some forward momentum (again...HOW? ) when you hit the ground on top, then SCOOT.

I look at just the vertical part and think, 'Nah. I don't wanna die.'

I looped my bike later that day, but on a 'normal' steep slope/rutted/root mess you would have trouble standing on. Even so, the ground drops a good bit away from you when you're doing the somersault-downhill thang.

Do that on that big a vertical? The ground you're gonna hit is a whole lot farther away than on 'just a hill'.

[/hijack]

"I look at just the vertical part and think, 'Nah. I don't wanna die.' "

I've got a video from a few years ago (VHS, man) of some guys climbing this clay bank in a sand pit nearby. At least 20' high, smoth sandy transition at the bottom to vertical the last 5-6', hard clay.

I wouldn't do it. It did not look like they were obeying the laws of physics. They'd go straight up, 3-4' straight up off the top, straighten it out in the air, land flat with almost no forward momentum.

Not for me, I'm too old

I've seen just that at a local staging area. Yep..a GOOD 20' of decomposed granite with a .....->) lip. I watched the guy go round and round, do it over and over on a CR250.

I understand the 'spinning wheel is lighter than not' idea of hitting the front brake to bring the front-end down when you're in the air..same as revving the rear to drop the front.

At least...I think it's something like that.

Not something I want to 'spearmint with.

I like a good hijack when it goes away from mechanical minutia towards riding physics minutia.

here's the crf quarry:


of climbing vertical faces: I think as long as the run-up is sufficiently long and that said vertical face is sufficiently short, forward momentum will still be preserved, carrying the bike past the lip. The compression of the suspension at the face preserves the momentum. If the vertical face is long enough, it will cause the suspension to enter the rebound phase and kill the forward component; skyshot.




the top of those paths were vertical before we shot up them repeatedly, you could go really fast and high and still travel 6-10 feet past the lips, which were only 2 or 3 feet vertical. i think the bikes were 1980 yz250 and 1982 husky cr500, too poor for protective gear, i guess.

Re: 'I think as long as the run-up is sufficiently long..

In the case of the 4-fiddy's, the run up was maybe 3 bike lengths. There was more 'up' than the vertical (and over-vertical) parts..overall maybe 10-12'? Not huge, but it was close.

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dentvet wrote: The gov shaft is twisted when the bike reaches 6000 rpm. The twisting is caused by narrowing of the gap in which the flat end of the gov shaft resides. The flat end is at an angle with respect to the axis of the crank. As rpms rise, the crank gov compresses two plates towards each other, which pinches the end of the gov shaft, making it twist through a cam action. The two plates or discs are held apart by a spring. Is this anywhere close to being accurate?

I know its wordy and the only reason I typed it was to learn more about the bike . . .

There are 4 balls in the KIPS governor assembly. When the centripetal force the 4 balls make against the inside of the "dished" part of the KIPs assembly - whose action tends to force the dished part away and against the spring - is greater than 1)the tension of that spring AS WELL AS 2) what little tension the spring/ball in the LH side of the cylinder provides, the KIPs actuates. MOST of the resistance against the opening of the KIPs comes from that spring in the KIPs assembly.

In this first picture you can see the four balls. Note that they are kept in those channels by the "dished" part shown to the left of the balls/holder . . .



If what I'm saying is confusing, the next picture of the assembled governor may help clear it up (as unclear or blurry as the picture may be). You should be able to identify what looks like a slotted mag wheel as the other side or back of what I called the ball "channels". As RPMs increase, those balls move within those channels radially to a point where the centripetal forces actually open the pieces against the force of the spring. If you get the chance to feel the stiffness of the spring you will be impressed with what forces those four little stainless steel balls can generate.



Hope this helps, I can appreciate wanting to understand!!