KDX200 - what happened to my top end???

[Canadian Dave]

GS you've replaced the clutch plates, did you measure the clutch springs while you had it apart?

Have you checked to insure the power valves aren't carbon seized, a very common problem. Pull the pipe and have a look up into the exhaust port. The sub port valves should be in the fully closed position. From your description it sounds like one or both of the valves may be stuck in the open position.

If you are going to do some work on the carb i.e. rejetting pull the carb off the bike and make sure its clean inside and out. Run to some place like Canadian Tire and pick up some carb cleaner. Disassemble the carb and go to work. Don't blindly start changing jets. Clean the carb and record what jetting is presently in the bike, including the jet needles clip position, and go from there. The stock jetting is likely too rich. A good starting point would be a 30 pilot jet, stock jet needle in the 2nd from the top clip position and a 330 main jet.

Have you recently done a compression check or serviced the top end?

Have you changed the spark plug?

The sprocket isn’t the problem though it is certainly worn out.

David

 

[dirt bike dave]

Let's recap.

1) The bike will over-rev in first and second gear unless it is short-shifted.

2) It revs way too high in first gear when he cracks the throttle, but pulls fine in 3rd and higher gears

3) It has new clutch plates and a badly worn front sprocket

My questions is: When the bike 'over-revs' and 'revs way too high' is it accelerating strongly or just maintaining its speed even though the engine is speeding up dramatically?

If the engine revs are increasing and the bike speed is staying the same while the clutch is engaged, something in the drive train is slipping.

 

[Green Streak]

first off I want to thank all of you for your hepful suggestions. I have a used other forums (not for my dirtbike) that allowed unregistered people to post and you get back a lot of stupidity!

I'll try to 'very' clearly explain the way my bike is acting. I wish I could attach a .wav file so you could hear it firsthand but my bike is in pieces.

When I am in first gear and start off at normal speed everything is fine. As soon as I twist the throttle (more than 1/4 open) the bike will not go any faster in that gear. If I keep twisting the throttle (1/4 to full) it sounds like the bike is red-lining (too bad enduros don't have tachometers). However the 'sound' remains the same throughout the 1/4-fulll throttle in fist gear.
The same is true for second gear.

As for my carb. I have taken it completely out. I have a 300 main jet and a 22.5 pilot jet. I just went to a dealer today and ordered the stock jets which are 320 mian and 25 pilot. The jet needle is on the 2nd groove (from top).

The carb is pretty clean but I will pick up some carb cleaner at CT.

As for my clutch plates I did not do them myself - I had a mechanic do them since I was in a hurry to ride earlier this season. When they were done he told me I did not need new friction plates as they were in good shape. I do not know if he checked the spring(s).

My top end is new and and I have a new piston (7hours on it - fast riding but not racing).

I would pull the bottom end out and re-look at it but don't you need some special tools to do so? (i.e., crankcase splitting tool, gear holder, etc..)

As for the 'power valve' I assume you are speaking about Kawasaki Integrated Power Valve System (KIPS) - my bike does not have this.

Sparkplug is brand new - old one was black with carbon which probably meant I was running to rich.

I did the obvious (to me ) sparkplug, air cleaner, clutch plates and still have the problem. The dealer will probably have my my parts (jets/sprocket) by Wednesday.

Why am I getting the feeling my problem will still be there???

Maybe it's time to buy a new(er) bike!......

 

[spanky250]

By your description, it sounds like the bike is running very rich. You say if you exceed 1/4 throttle, the bike stops accelerating. Does it run smoothly when this is happening, or is it very blubbery? Does it smoke a lot?

 

[dirt bike dave]

OK, I'm still a little confused about the description. When you say
'it sounds like the bike is red-lining' do you mean the bike is actually reving super high? Or do you mean it sounds like a bike or car with a rev limiter hitting the rev limiter?

 

[andrew]

I wouldn't say he's running too rich - not with a 300 main jet. I used to own one of these very fine machines, and my experience was that the optimal jetting for this bike is a 310 main (320 was standard). I left my pilot jet standard.

I can remember having a similar problem, that is a feeling that something was slipping somewhere. I replaced clutch plates and springs but the 'feeling' never went away. By the time I noticed this 'feeling', I had put a 240 kit through itand was having all sorts of problems getting the jetting 'just right' again, and I put it all down to that, the extra torque generated etc.

I never did get it sorted as my desire for water cooling and a rear disc brake overcame my fear of spending lots of cash, and so I went and got a '96 model and never looked back.

I know this post mightn't give you much joy, but if you're determined to keep it I'd look at ALL the clutch components, followed by the transmission components. Remember, it IS an old bike. And BTW, my '87 DID have power valves - I'm pretty sure they were introduced in '86.

Cheers,

 

[Brian Grau]

you allways have to eplace the drive plates friction plates and springs on mine i did the friction plates and it was grabby and didnt work rite so i did the drive plates and its been fine ever since.

 

[Canadian Dave]

Before we go any further you need to ID the year of your engine.

"As for the 'power valve' I assume you are speaking about Kawasaki Integrated Power Valve System (KIPS) - my bike does not have this. "

If it doesn't have power valves its an 85 or older engine/bike rather than an 87. Check it out and get back to us. We can't make meaningful jetting recommendations with out knowing.

David

 

[Green Streak]

more like the rev limiter scenario

 

[spanky250]

I think what he is experiencing is an inability of the engine to rev above a certain throttle opening, due to an overly rich condition. It is not as much of a problem in the higher gears because the increased load is allowing the enigne to at least attempt to burn all that excess fuel. The fact that you say it occurs beyond 1/4 throttle opening is a big clue that there is a fuel problem. Green Streak, I think you need to check the float level, and the condition of the reeds.

 

[Green Streak]

Originally posted by Canadian Dave
Before we go any further you need to ID the year of your engine.

"As for the 'power valve' I assume you are speaking about Kawasaki Integrated Power Valve System (KIPS) - my bike does not have this. "

If it doesn't have power valves its an 85 or older engine/bike rather than an 87. Check it out and get back to us. We can't make meaningful jetting recommendations with out knowing.

David

My bike is definitely an 87 KDX200. Here is a pic of it in it's current state of disassembly..

I checked the VIN number as well - just in case I was going crazy...

I have checked Kawasaki service manual that I have as well as my more detailed 83-88 Clymer service manual and neither reference power valves.

Are they called something else?

Forget it... your right! It is under 'exhaust advancer assembly' along with cylinder replacement.

 

[JohninKY]

I think I see the problem. The rear wheel is not attached. Sorry, couldn't help it.

 

[TobyS]

I have a '95 KDX200, and my clutch slipped just like you describe (near as I can tell), because the clutch basket had notches worn in it where the fiber disk tabs drive the basket fingers. I think these notches keep the clutch plates from coming together under torque. I paid about $180 dollars for a new basket, and that fixed it.
There are these guys called "surf and turf racing" (on the net) who will CNC machine a basket to remove the grooves, while maintaining the correct angular spacing (although the friction plate tabs will have more clearance) for $50. This worked great on my son's YZ125.
I should mention that I replaced the friction (fiber) plates on both bikes, but the old plates were still within spec and didn't look bad, especially the KDX.
Ask your mechanic if he looked for notches. If not, you might have him check.

 

[Green Streak]

Ok guys I need some help. Canadian Dave said check my power valves. So since I had carb out, etc.. I took my top end of to see them.

What I have is one open, one shut. When I pull the operating rod out a bit the one that is hut opens and the one that is open shuts. I am assuming this is screwed up. Right? see picture - it may help..

GS

 

[Canadian Dave]

When you say the right valve is open when the left is closed do you mean open to the chamber (Halmhotz resonator) on the right side of the cylinder or do you mean open to the exhaust port?

Both valves should be open/closed to the exhaust port at the same time. If the left valve is closed to the exhaust port and the right open to the resonator but closed to the exhaust port then all is well.

Good point re: the clutch basket. This is a common problem on older bikes. You can redress the fingers with a file and get some more life out of it if they are groove and the plates are catching. If this were the case however I'd expect the plates to catch in all gears and at times not initially engage when. Its worth asking the mechanic, though I expect he would have informed you if there was a problem when it was rebuilt.

David