Just acquired a KDX200

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HarryCallahan
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Just acquired a KDX200

Post by HarryCallahan »

Just acquired a '99 KDX200, on the original chain and tires (still has the dimples in the front tire center knobs!). Runs like a champ, and has great acceleration (for and old guy like me!).

Regular maintenance has been done to it like trans oil, clean and oil the air filter and replace a broken part here or there, but no top end stuff. I ordered a service manual, new x-ring chain and sprockets plus a Weisco piston kit with bearings and wrist pin just in case. I am considering running a 'shock treatment' of Yamalube Ring Free thru it to clean up the top end, anything else I should consider? Other stuff on the list might be brake fluid, fork oil and bearing grease for starters. I would like to keep my good fortune of finding this bike in good shape going.
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m0rie
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Post by m0rie »

Welcome! Sounds like you've got a pretty good handle on what needs to be done. You might also want to consider respringing your front end while you've got it apart to change the oil. There is a lot that can be done to a KDX to allow it to grow with you as your skill level increases. Have fun!
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Colorado Mike
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Post by Colorado Mike »

if it's a 200, the stock piston is a good one. the 220's are the ones that use surplus grenades for pistons. If the thing has as little hours as it sounds, I don't see why you would do anything to the motor.

By all means, disassemble and lube all bearings in the rear linkage/swingarm and especially the steering head. Change the glop in the forks, but use fork oil instead. spring the forks to your weight, Honda XR400 springs work well.

Then RIDE!! :supz:
Mike

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canyncarvr
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Post by canyncarvr »

You might take a look at the KIPS..make sure it's OK.

Remove the slotted cap over the KIPS main shaft on the LH side of the engine. Start the bike and ensure the rod moves as it should when it should (6kRPM+). That the main shaft moves doesn't ensure the valves in the cylinder are OK..but likely are with an 'H' series KDX.

Next time you have the pipe off, look up into the exhaust port and while manually activating the KIPS via the nut under the mentioned cover, look at the two subport drums and main valve to see that they are timed correctly and moving properly.

BTW...riders with the OEM forks generally really like taking a couple of the large shims off the compression stack. There are something like 6-24mm before the taper starts..take off two of them.

Haven't heard that it is necessary, but DO make sure the removal of said shims does not leave you with a short stack that will not give you enough threads to tighten it up with.

The XR springs CM mentions are a great improvement. Set the oil level to about 110mm and the preload to something not nearly as stupid as the 35mm+ the bike comes setup with.

Set your shock sag. Shock clickers have more effect (on the shock) than the fork clickers do (on the forks).

Wheel bearings? If you need those, consider them from CBR bearings. Lifetime warranty. Not cheap as the junk you get from the local shop aftermarket-wise, but the last a good bit of time..and don't cost anything ('cept seals and shipping) when they DO give out.

Have fun!!

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HarryCallahan
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Post by HarryCallahan »

Good tip on the fork springs, I will pick up a set - any particular year XR400? On the subject of fork oil, I could use some experienced help choosing a weight. I figure I am a little heavier than normal rider weight, lets say 275lb, and I don't plan on anything radical as far as terrain or riding activities goes (excluding unplanned stuff!). What would be the proper weight and quantity for the oil with the new springs?
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canyncarvr
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Post by canyncarvr »

The OEM forks use oil viscosity as rebound control...having no rebound adjustment. I have no experience with how thicker viscosities change 'stuff' in the OEM fork. Still, I'd probably start with 'regular' until I knew different. I've used Mobil-1 ATF mostly..that based on a rec from the tuner that revalved my OEM forks (Wilkey).

At 275#, probably leave the original shim stack (don't take off the two 24s mentioned) until you think otherwise.

As far as the XR springs go...I've lost (can't find it anyway) the write up I had on what years have what. You can use RaceTech's spring rate search and catalog to pick what suits, though. The XR springs run around 530mm in length, the OEM springs are 470mm with a BIG metal spacer making up the difference. Pick a spring of the correct diameter and 530mm long and it doesn't matter if it's listed for a Yamaha or anything else.

RaceTech's rec is a spring around .50kg/mm for your weight. RT's recs are generally on the high side. Even a bit lower..say .46/.48 isn't something you will find as OEM equipment on an XR. The OEM XRs were in the .38/.42 range on the higher side.

275# will likely need a stiffer shock spring, too. Set your race sag to 100mm, then check the free sag. If free sag is <1/2" (I'll bet you won't have any!), you need a stiffer spring.

It's the balance of the bike front-to-rear that's important.

Oh...quantity. The forks are not measured that way. With the spring out, the forks collapsed and the rod down, check the oil level. Use a large animal syringe with a piece of tubing attached to reach 100mm (or your choice) inside the tube. Overfill the fork, clear the bubbles (pump the rod), remove the excess oil with the syringe.

The air shock (air space above the oil) acts toward the end of the fork stroke..the less air, the more resistance to bottoming. Obviously valving and spring rate work into the equation, too. 100mm is considered pretty much 'normal'. My preference on the OEM forks was 115mm. That was with .38 XR (530mm) springs set to 3-5mm (I don't recall for sure what I ended up with) preload. I'm 175#....or so. :wink:

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