My 87 KDX200 project.

Reference and discussion for the various air-cooled KDX models
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kawagumby
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My 87 KDX200 project.

Post by kawagumby » 08:23 pm Jun 23 2012

The chassis is nearly done, and I'm in the middle of the engine rebuild.

The forks are 04 YZF with .39 springs and modified 08 WR250F compression stacks. EDIT: I took out the WRF compression stacks...they didn't work well at all, they're mostly just a blow-off setup and didn't respond quick enough in stutters and such. I ended up using revalved 02 YZ125 stacks, revalved based on previous success with YZ units - now the forks work very well.

The rear brake is H model with an 04 yamaha integrated master cyl. reservoir
The rear wheel is a 2001 KX125 - same hub and rotor size as the H model KDX.
I'm going with the stock valving in the shock for the time being, once I get it out on the trails I can figure out if it needs any changes.


I'm looking forward to seeing how this bike will handle the rough single track I like to ride!
Last edited by kawagumby on 06:13 pm Mar 27 2014, edited 3 times in total.
1994 KDX200, Beta Xtrainer, 2 yz125's, kx100 modded for adult, cf150rb modded for adult, gasgas contact 250.

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My 86 KDX200 project.

Post by SS109 » 01:26 am Jun 24 2012

Man, that is going to be one pimpin' air cooled KDX! :supz:
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Current KDX: '98 KDX220
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My 87 KDX200 project.

Post by kawagumby » 07:40 pm Jun 26 2012

Well, I got the engine in today and it fired about the 3rd kick. It's jetted pretty rich (the left side crank seal was shot so the PO probably tried to compenstate by jetting rich). But, I was happy to get it running and took it up and down the street a few times. I'm always uptight about tranny stuff when I'd not been able to ride the bike before teardown - but all 4 gears worked... :mrgreen:
When I get it finished, I'll post some pictures. The bike still has some bugs, jetting and the clutch side case gasket is seeping (cheap gasket set, never again)...


BTW, this bike was a rust pile...rust even in the engine - the oil had leaked out and water got in - the steel clutch plates were rusted, the crank had rust...what a mess. All the plastics have been replaced except for the side panels.

I rebuilt everything, every nut and bolt was inspected and replaced if necessary but now I'm poor again... even ebay is out of control on most prices now...but it was worth it, I think :rock: .



Here they are:

Image

Image
1994 KDX200, Beta Xtrainer, 2 yz125's, kx100 modded for adult, cf150rb modded for adult, gasgas contact 250.

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My 87 KDX200 project.

Post by kawagumby » 02:19 pm Jun 28 2012

I took her out for nearly 2 hours of ride time and suspension tweaking. The bike ran perfectly and was fun to experience.
As you would expect, the power was down some compared to my H models, but not bad....and for slower trails, the difference is negligible. The torque curve is shorter, but max HP isn't that far off, IMO, maybe 4 or 5 hp compared to my other bikes? I was using an old stock H model 47 tooth rear sprocket for the ride, but I think I'll go back to the C model stock 48 tooth as you can tell it winds up a bit slower in 6th gear and the lower gearing should help that. I didn't think the lower gears needed the change, they are the same exact ratios as the H model.

The air-cooled motor when worked hard sends more vibration up through the handlebars than the water cooled bikes - my hands went to sleep a couple of times -
The air-cooled motor does not like long drawn-out WOT hill climb situations...it brought back memories of hot, smelly engines and pinging from the good old days, LOL.

With the modern front end and the bar mounts moved over 1/2 inch further forward, the bike no longer has that old school feel to it, rather it feels more like any other bike. I think the stock KDX bar locations are too far back for all models, and they kept it there to work the rear suspension more rather than the weak front forks...just my take.

It is a great turning bike, and with a little more suspension tweaking, I think the lightness and lower CG will make this a great addition to my KDX stable. (It got a few looks while hauling it to the park too). :supz:
1994 KDX200, Beta Xtrainer, 2 yz125's, kx100 modded for adult, cf150rb modded for adult, gasgas contact 250.

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My 87 KDX200 project.

Post by KDXGarage » 09:21 am Jun 29 2012

WOW! She looks great. You have done a lot of work to it. Thank you for keeping one going, as well as the ride report.

The pictures did not show up for me in your thread, so let me try to display them.

Image

Image

Image

Image

Image
Last edited by KDXGarage on 08:50 pm Jun 29 2012, edited 1 time in total.
Thank you Julien D for all your hard work!

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Re: My 87 KDX200 project.

Post by kawagumby » 09:31 am Jun 29 2012

Thanks for the compliments...man, it was a LOT of work.. but it was fun too. My wife says I like to "recycle" machines.

If it is possible, it might be a good thing to copy the pictures to a new file name - the image posting site is free and they probably drop the pictures after a while.
1994 KDX200, Beta Xtrainer, 2 yz125's, kx100 modded for adult, cf150rb modded for adult, gasgas contact 250.

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Post by KDXGarage » 07:52 pm Jun 29 2012

I bet it was a lot of work.

I like the pipe and spark arrestor. Though my 1987 KDX200 is far from assembled, I do have those on mine.

On the pictures, pick 5 names, and I will put them on my site within a folder with your screen name on it. I will then go in and edit my post, pointing to the new location.

EDIT: I saw that they were already named, so I went ahead and copied them over.
Thank you Julien D for all your hard work!

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Re: My 87 KDX200 project.

Post by kawagumby » 09:23 pm Jun 29 2012

Thanks for copying those pictures....

When I bought this bike for $500 it was junk. One of the reasons I bought it was the pipe and spark arrestor...the pipe wasn't dented but it was pretty rusty. About an hour of steel wool and naval jelly and it looked pretty good.

The intake system was leaky so the engine had taken in some dirt. It had a fresh wiseco piston that was ruined from that dirt, but the cylinder surface was perfect... weird. You could tell that one of the previous owners had tried to keep it up, but the last owner was pretty lame. He kept it in a yard and didn't even put a tarp over it. I wouldn't have normally bought a bike in that condition, but C models are pretty scarce and this one was located just a few miles from where I live.
I had to laugh when he told me it was normal for the bike to rev high then slow down...I could tell right off the flywheel side crank seal was gone. It barely ran and had no brakes, so the tranny was a crap shoot, but as it turned out, the tranny was OK tho' the clutch was rusted up.
What a challenge - ebay provided enough used parts to cobble together a good machine, but it wasn't cheap - I spent more than I had planned, for sure.

Have fun putting your 87 together!
1994 KDX200, Beta Xtrainer, 2 yz125's, kx100 modded for adult, cf150rb modded for adult, gasgas contact 250.

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Post by KDXGarage » 09:20 am Jun 30 2012

Thank you for the further details on your 1987 model. It sounds like the previous owner was a regular Mr. Goodwrench! :naughty:

The pipe really wakes them up. It is the best power related mod I ever did to my 1987.
Thank you Julien D for all your hard work!

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My 87 KDX200 project.

Post by factoryX » 11:42 pm Jun 30 2012

Interesting. Did you mod the stock swinger or throw a E/H series one on? Looks incredibly light.
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Re: My 87 KDX200 project.

Post by kawagumby » 09:24 am Jul 01 2012

I modified the original swingarm. The E/H series will not work for a variety of dimensional reasons - they are completely different due to the different linkage.
It is light. One thing I noticed while working on the bike was the very simple and light frame. The engine is lighter than the E/H models also, as it is narrower and lacks the upper weight due to water cooling.

Edit: I weighed the C model low end ass'y vs the H model low-end ass'y and the low-end alone weighs 2.5 lbs less than the H model. So, if you consider the radiators, shrouds, coolant hoses, etc... you're probably looking at another 3 lbs...so the C model complete engine is probably about 5-6 pounds lighter than an H model.
That lightness and the fact that the seat height is lower means it is very easy to use as a tight-trail forager...

It feels as light as a pure mx'r but is lower, with a lower CG and a more trail-riding friendly seat - and it already has the right gearing and rear suspension for trail riding too...

I was thinking about building a hybrid, but came to the conclusion that this would be a better trail bike for the ergos and kinds of trails I like. I was a little worried about the rear suspension, but it is working as well as anything else I've owned (the shock is completely rebuilt and valved with a touch more rebound than stock).
Last edited by kawagumby on 03:02 pm Aug 15 2012, edited 1 time in total.
1994 KDX200, Beta Xtrainer, 2 yz125's, kx100 modded for adult, cf150rb modded for adult, gasgas contact 250.

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Post by KDXGarage » 10:57 am Jul 01 2012

How did you do the rear brake conversion? I looked at mine and was thinking of doing a 1989 - 1994 KDX200 wheel and brake parts.

Did you modify the swingarm or the brake carrier?
Thank you Julien D for all your hard work!

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Re: My 87 KDX200 project.

Post by kawagumby » 12:34 pm Jul 01 2012

Just the swingarm. Check out how the stay for the C model rear hub is welded...it is a separate sheet welded at the edges near the top and bottom of the swingarm. Those welds are easily removed with a grinder, if you're careful you won't even touch the swingarm itself - grind away enough to lift one end and it can then be bent over and broken off. Clean up what's left with a grinder or file. Then, find some weldable grade aluminum to act as the stay for the E or H carrier. It will end up being wider than the E or H model stays (meaning further out toward the wheel), as the C swingarm is wider with the new wheel still located left with the original C axle spacer (the 125 wheel with the original C wheel spacer placed the rear sprocket exactly the same position as the C wheel - lucked out!).
I found a chunk of wide aluminum angle that would work as the stay and had it welded on for $25, a price which included welding the chain guide tabs. So that part insn't a deal breaker. The fit of the stay to the carrier isn't that critical, IMO, as long as the up-down play isn't too excessive. If you notice, the E and H carriers are tapered for easy ass'y so you have more slop when the wheel is further back anyway - and the widened "T" edges are for alignment too, I think. So just using a simple rectangular-shaped stay works fine, the penalty is a little more hassle during wheel mounting.

BTW, I used a H model carrier, but I think the E model is likely the same. I bought a junk E model swingarm just for info purposes, so I had access to all three models of swingarms for comparision.
1994 KDX200, Beta Xtrainer, 2 yz125's, kx100 modded for adult, cf150rb modded for adult, gasgas contact 250.

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Post by KDXGarage » 01:34 pm Jul 01 2012

Thanks for the info. I saw Jeff Fredette with one on his 1987 at a national enduro back in 1987. I thought it was a very neat idea. I have always wanted to do it.
Thank you Julien D for all your hard work!

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Re: My 87 KDX200 project.

Post by kawagumby » 12:21 pm Jul 02 2012

I thought some of you might get a kick out of seeing my first kdx200 in action at the Virginia City GP in 1987...brought back a trophy that day too...

OK, so I'm an old dude....

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1994 KDX200, Beta Xtrainer, 2 yz125's, kx100 modded for adult, cf150rb modded for adult, gasgas contact 250.

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My 87 KDX200 project.

Post by hbgod » 09:42 pm Jul 07 2012

damn that thing looks sweet. i thought my kdx would be the nicest looking Air cooled bike on here...... you definetly got me beat. im keeping it pretty much original other then what needs to be replaced
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My 87 KDX200 project.

Post by zz3gmc » 05:34 pm Jul 21 2012

Your bike looks really good! I wonder if a similar disc setup would work on my 84 200 project. I believe the rear hub is the same as the 86 and up. I used to race a 84 200 and 250 in enduros and always hated the rear brake. I ended up swapping the 84 KDX250 rear wheel and ended up with bigger and better brakes. Did the same thing with the front end. My 200 hub was so worn out from all the dirt and mud that I was replacing shoes every race!

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Post by SS109 » 06:34 pm Jul 21 2012

Your bike turned out absolutely gorgeous! It is now too pretty to ride! I tip my hat to you.
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Current KDX: '98 KDX220
Old KDX: '90 KDX200 -White/Blue

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Re: My 87 KDX200 project.

Post by kawagumby » 11:16 pm Jul 21 2012

Thanks for the compliments, but don't worry it'll look like any other bike soon...I plan to ride it where there's rocks, brush and plenty of places to get out of shape...

zz3gmc - you're right about those rear hubs, that memory is what drove me to install the disk brake - once the drum was oversized the shoes wouldn't last long. I even welded extra metal to the brake cam to keep it from over-centering and locking up...what a PITA - and they didn't work well when wet anyway. My first small bore was a PE175 and I too went to putting an RM 465 front end on so I could get better braking (drums front and rear) back then brakes weren't anything like they are now.

As far as converting your 84, if the axle size is the same as the 86, it is the same as the E and H models (and early 2000 KX125's) so yeah, you can do the same conversion using any of those wheels and brake systems. :grin:
1994 KDX200, Beta Xtrainer, 2 yz125's, kx100 modded for adult, cf150rb modded for adult, gasgas contact 250.

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My 87 KDX200 project.

Post by zz3gmc » 09:22 am Jul 22 2012

I have a leftover rear hub from my 500 hybrid project. I did some research and the 01 125 hub shares the same bearings but the hub has a different part #. Im going to drag my 84 out and see if the axle is the same size. Or I could just check bearing #s online. I have the triple clamps from a 89 200 and I think the 84 shares the same head bearings. I was thinking of trying 43mm forks. I have a set of 99 DR350 fully adjustable cartridge forks laying around, actualy they are on my 81 PE400 now. I swapped a 84 RM250 triple clamp onto it and mounted the forks. They made a huge difference over the spindly 36mm forks! Im not sure what to do with the shock, Someone swapped what looks like a mid 80s KX shock (remote reservoir) onto it. I may try to work with it.

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