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I picked up a 01 KDX last summer and rode it a few times before cold set in. PO did not mention of the motor had ever been touched. Looking at the head I do not see any marks on it looks un touched. The bike runs fine so I am on the fence as to what to do. Should I at least pull the head and see if it has the stock piston? Can you tell this just by pulling the head? Is there a way to test the KIPS to see if it is working?

Mike

Is this a 200 or a 220? If it is a 200 then just do a compression check. If it checks out good then it's good.

If it is the 220 I would pull the head and/or cylinder to make sure it what piston is in there. I'm not sure which is required as I haven't had to worry about it myself so I didn't pay enough attention as to how to identify the piston. As you probably have heard, stock 220 pistons like to grenade with no notice. If it is stock replace it ASAP with a Wiseco and get back to riding!

Is it a 200 or a 220? If it is a 220 you should replace the piston. (many a post about that, just search.) If it is a 200 it could be fine. you could take a compression test and see where that is at. Also you could pull the pipe and look in at the front of the piston and the rear of the cylinder to get an idea with out having to pull the cylinder. I have a 2000 200 that still has the original piston and rings with 150 psi of compression. I forget the low end of spec but I think it is around 98 psi. I could look but the book is in the cold garage. The top end spec is 151 I do belive.

The kips can be checked thru the slotted plug on the left side of the cylinder. Remove the plug and start it up. Rev the bike up and you should be able to see the gear turning. The KIPS opens around 5000 +/- RPMs. You could still have an issue with a part of the kips but that should tell you if it is moving at all or not. Good luck!

SS109 wrote:Is this a 200 or a 220? If it is a 200 then just do a compression check. If it checks out good then it's good.

If it is the 220 I would pull the head and/or cylinder to make sure it what piston is in there. I'm not sure which is required as I haven't had to worry about it myself so I didn't pay enough attention as to how to identify the piston. As you probably have heard, stock 220 pistons like to grenade with no notice. If it is stock replace it ASAP with a Wiseco and get back to riding!

Ya like he said!

I'm gonna go ahead and disagree with everyone. If I bring home a used 2t with no documented evidence of a recent top end replacement, I'm putting in a piston and rings. It gives you a chance to check the condition of the cylinder and the bottom end, and provides you cheap insurance. In the case of the KDX it also gives you an opportunity to clean and inspect the KIPS valves, which is very important.

New top end = cheap. Rebuilding everything after a grenaded piston or rod bearing = not cheap.

I agree Julien but it depends on what the OP wants to do. Some don't want to replace parts or tear things apart unless they absolutely have to. I was just posting up what I consider the minimum on what needs to be done.

True, a new top end is good way to get peace of mind. The thing to ask is.
1. How used is the bike, has is been rode a few times and sat in someones garage forever? Or has is been beat to death and neglected?
2. How much money do you have? If you have a couple hundred sitting around that needs a new home it would be a good place to spend it to know what you have.

It is your bike, you know what you want of it. As I said before I am still running a 11 year old piston. My bike was hardly used and it showed in every way before I bought it. I had the engine apart last fall and the piston looked like new after I wiped off the carbon from the top of it. My budget didn't allow me to replace it at the time so it went back in.

It s a 220, I have rebuilt Harley motors but that Kips valve has me worried, looks pretty complicated. I have done some checking and found some shop manuals looks like it will be around 75 bucks for those then a piston kit at another 140 or so. I am pretty mechanically inclined, with that being said is the KIPS valve something that a novice can tackle? Really worried I will get it all apart then have a pile of parts I can not get back together. Any one know of a good engine builder in Colorado Springs CO?

check the link at the top of this page for a better deal on a service manual via cyclepedia. get it, and print out what you need when you need it.

If it's a 220, and it's possible that it still has the original piston, it is IMPERATIVE that you get it out of there asap. When those pistons let go they can cause some major carnage. You will want to use a Wiseco in place of the cast OEM piston. You can find a better deal on that piston kit, check ebay and shop around. I got my last wiseco on Ebay for about $70.

The KIPS valve is more technologically advanced that *anything* on a HD motor. That said, it is not rocket science. Take some pictures as you proceed, and do a little research before you begin. There are a couple of important details you should know about before you touch it - like holding the shaft with a wrench before you attempt to loosen the left hand threaded nut.....
I do tend to agree with Julien. When you buy a 2 stroke of unknown history, it is usually best to at least do a top end job as soon as you can, so you have a base line for future maintenance. In my case, it doesn't always work out that way, though. My used '04 200 has been ridden for over a year by me, without a top end job yet. It feels good when I kick it over, so I will get to it when I get to it. But that is a chance I decided to take......I really should get after it now, though.... :-)

Julien had said to look at the repair book at the top of the page but due to recent events you should get a hold of KDX Butterfly before ordering any thing from this site.
http://kdxrider.net/forums/viewtopic.php?t=10163

And like the other post had said, the KIPS is not that bad to deal with. Pay attention when you take it apart. NOTICE some repair books have the left and right valves marked wrong in the book and some do not. The book I have has the error in it so make sure you keep track of them when removing them.

And yes if it is a 220 you NEED to replace the piston.

rbates9 wrote:Julien had said to look at the repair book at the top of the page but due to recent events you should get a hold of KDX Butterfly before ordering any thing from this site.
http://kdxrider.net/forums/viewtopic.php?t=10163

No worries there man. The online manual link at the top of the page is a direct link to cyclepedia. No funds would be transferred or sent to kdxrider from there. I wouldn't have suggested it were that not the case

Under $25 with great color pictures, and you can just print the sections you want, or print the whole dang thing if you want to.

juliend wrote:

rbates9 wrote:Julien had said to look at the repair book at the top of the page but due to recent events you should get a hold of KDX Butterfly before ordering any thing from this site.
http://kdxrider.net/forums/viewtopic.php?t=10163

No worries there man. The online manual link at the top of the page is a direct link to cyclepedia. No funds would be transferred or sent to kdxrider from there. I wouldn't have suggested it were that not the case

Wasn't sure how that one worked and didn't want to see money tied up for months. Thanks for letting every one know!

Even with the power-valve this thing has about 300 less moving parts than your harley....so you'll be fine.

Ok I think I will get the online manual for now, this may be a dumb question but can you just change the piston without getting in the KIPS valve? Can you clean the valve up with out taking it apart?

You still need to remove the shaft actuator that NEEDS to be supported when you remove and put back together (that's the one with the left threaded nut)
It's really not that complicated at all, might as well clean everything while you're in there.
It doesn't take much longer to remove everything, and clean it real good.
With the manual shouldn't be a problem, if you're lost or not sure, take pics and ask us

Ok I just purchased the manual, I am going to go for it. If it warms up this weekend might start tearing it down. Looking at the steps once I remove the exhaust valve actuator shaft the top end will come off correct? The bike is at a buddies so if I could just take the top end home then I could clean up the kips and what not...