Kips Valve Question

[jjm7384]

I was riding at the local motocross track and came off a jump when all of a sudden it sounded like a marble was inside my engine. I immediately shut the bike off and pushed it off the track. When I took apart the engine, I found that the Kips arm (small metal plate with pin attached inside the engine cover) had broke and took out my clutch basket and spur gears. Needless to say the $8 part caused almost $400 worth of damage, but I'm curious what would have caused this. Could the valve maybe lock up? I moved the actuator shaft that controls the valve and it moved freely in and out with no problems. It appears that the Kips arm just failed...Is there anything else I should check before I put it back together and ride? This part of the engine was never taken apart before. I need a reliable trail bike (luckily it happened on the track)...Has this happened to anyone else?
Bike Specs: '93 KDX200/aprox 1200 (original) miles/Ported Polished/rad valve/weighted flywheel/R&B Carb/Pipe/Silencer/Air Box Mod/Race Tech Suspension/110-100 Rear Tire/13-50 Gearing

 

[canyncarvr]

Yes it has happened to others.

It is most likely a result of:

1. Not knowing the nut on top of the shaft is LHT...and in 'loosening' it (which is actually tightening it), the shaft is tweaked.

2. NOT holding the shaft at the flat when the above nut is removed, which fatigues the shaft.

You mention the bike was not apart before (you say 'this part'. The above would happen without 'this part' being apart). A '93 with NO kips service? That would be odd.

Especially since about that year, the KIPS rods that actually activate the subports are reported to be weak spots.

Other parts?

Yeah. Make sure the main flap and the subports work as they should. You mention binding....the top racks strip before the activating rod breaks. Well..unless one of the two (or both) fatigue issues have taken place.

 

[jjm7384]

CANYNCRVR, I purchased the bike last year with 280 original miles (which I know to be accurate). Can you elaborate on the "a '93 with no kips service" part? If you could let me know what I need to do and what "weak" parts I should replace while I still have it apart that would be great. I'm not a pro wrench so the more details you could give me the better. Thanks again for the info, and YES...I probably did tweak the shaft without knowing of the reverse thread!

 

[canyncarvr]

BTW...here's another KIPS story:

http://dirtrider.net/forums3/showthread.php?s=&threadid=8156&highlight=KIPS+shaft+broken+thread

A bike almost 10 years old that has never had the KIPS taken apart and cleaned AND it still works would be a surprise. The KIPS is in a nasty environment...and keeping it clean is important if you want it to keep working. A sharply jetted bike is a big + in this area, but hardly anyone's bike is jetted for diddle.

I did do a search (a couple of 'em) and didn't find what I was looking for as far as specifics on the '93 kdx. There are some years before '95 that had known weak KIPS parts...don't know about '93 specifically. I said that already.

When you say, 'this part was never taken apart before...' but indicate that it's a 'ported, polished' bike.....those two 'facts' are mutually exclusive. You have to mess with that shaft to get the cylinder off. That's when it got stressed and then broke I'd guess.

Take note of the above thread concerning parts.

One other thing...the LHT thread nut at the top of the shaft is a fer'sure on the 'H' models ('95+). No way you could have taken it apart and NOT know that. You would have broken the shaft then.

Anyway, certainly replace the shaft...make sure the subports/main valve operate and are timed correctly (subports closed at 'rest', open at the same time to the same point when activated and that the main valve works, too).

The kdx is quite reliable. It has quite a reputation in that regard.

Good luck

Another btw...the thread listed in BRush's post in the above thread isn't available anymore. The 'dreaded 404 error'....

 

[jpm200]

On the 1989-1994 models you do not have to undo the LH threaded nut to remove the cylinder or even to remove the kips valves for a service.

My 89 is currently apart (cases split and the crank out for a rebuild. I haven't touched that nut.

When servicing the kips valves with the cylinder still on the cases just remove the circlips on the end of the actuator shaft and the spool slides off.

When removing the cylinder the shaft doesn't even come into play.

 

[jjm7384]

Thanks for the help guys!

 

[canyncarvr]

jpm:
Thanks for a post that actually applies to jjm's situation.

I've read numerous times about earlier (not 'H') models having known KIPS weak spots. Which years does that apply to?

Would you expand on the '..doesn't come into play' part? If the actuator rod drives the KIPS through any sort of gearing system, how does it NOT require something in the way of attention when the cylinder comes off?

I'm headed to buykawi.com to look at a '93.......

Thanks for the lesson!

***edit****
Looks like the actuator rod is connected to the main shaft with a pin? Still, there's a nut on top of the actuating rod. Don't see how you could 'not touch' it to take the cylinder off. Learn me, please?

 

[jpm200]

CC:

Looking at the parts diagrams for the 1989 KDX200 (Engine cover and cylinder) on Buykawasaki. (I chose 89 because that's what I ride)

First on the engine cover drawing.
The lever part 13168 is held onto the governer shaft 49114A by a nut 92015 that has a left hand thread.

This lever engages the spool 92143 on the end of the governor rod 49046 (on the cylinder drawing)

The reason that you don't have to remove the LH threaded nut is that the lever sits below the spool allowing you to lift the cylinder away.

On the subject of weakness.
I think that 89-94 KDX owners need to consider the side kips valves as a consumable just like pistons and rings and replace them regularly. They are just aluminium parts and are subject to a pretty extreme environment. They are not expensive and it is an easy job
The LH valve has been labelled as a weak spot. It will fail before the RH valve because it has a narrower section of rack running on the gear giving higher stresses on the gear teeth.

Hope that this clears it up. Best I can do without taking a photo and my engine is currently in 1000 pieces while I try to complete a bottom end rebuild.

 

[canyncarvr]

Excellent!

Thank you!!!

I see the lever...and the spool. The lever fits INTO the spool, then? That's the direction the lever is facing (up as you say, so the cylinder would just be lifted off), so it fits into a hole on the spool?

Do you know of any reason the governer shaft would break in this (jpm's) case? In the earlier thread I referred to, a brand new shaft broke under thumb pressure....maybe jpm's just had a problem from the gitgo.......

Thanks again for the info. Learning stuff is good......:)

 

[jpm200]

Correct
The pin at the end of the lever fits in the groove in the spool.

One other difference on the 89-94 is that the governor shaft has no flats.

In the other thread I suspect that the new shaft broke because the nut was tensioned without supporting the shaft. Just a guess. I suspect that it wouldn't take too much to snap the plate off the bottom.

I need to check out the 95+ on to see the difference. Got me interesed.

 

[canyncarvr]

Differences: (some anyway).

There IS a flat on the shaft for support when removing the nut.

Which MUST be removed because there is a stamped/geared metal piece that drives a gear (by rotation..not levering) on the main shaft. That piece is on TOP of the gear, so it must be removed before the cylinder can be taken off.

There is a timing issue then, when the thing is reassy. You need to ensure the KIPS is 'closed' when the activating rod (obviously in a 'closed' state when you put it back together) has the stamped gear piece put on.

The same issues (I presume) with both systems are so...you'd want to be sure the subport shafts are timed properly (drums to side shafts to main shaft) before you hooked the activating shaft to the KIPS system.

I don't read that the nut on jjm's bike was removed. Like I said, he couldn't have removed that and NOT know it was LHT.

One other thing....the 'E' model pin must not rotate the spool...it must PULL on it? So instead of the main shaft rotating, it is levered back and forth?

Obviously that would be another diff 'tween the two systems.