1987 KDX200 resto project

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Goofaroo
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Re: 1987 KDX200 resto project

Post by Goofaroo »

Great. I just pulled the kickstarter off and the washer behind the nut holding it on appears to be a shim from the rear shock. Hmmmm. I am going to have to do some serious research to figure out the correct set-up for this rear shock. Would it help if I begged for information?
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Re: 1987 KDX200 resto project

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I was going to wait until my son was here to help but I decided to go ahead and strip it all down. Everything came apart easily and seems to be in good shape. I'm going to take the frame to the car wash and give it a good cleaning. The steering head bearings are in good shape and the forks don't appear to be leaking but I'll still take them apart for a cleaning and new oil, boots, and seals. I was given a set of bearings and seals for the front wheel so I'll install them and I also need to take apart the master cylinder and the caliper and give it a good cleaning. It will need new brake pads as it appears that the fork seals leaked profusely at some point and contaminated them.

Everything seems to be pretty straightforward at this point other than the shock debacle. I'm not loosing any sleep over it but it will certainly have to be addressed at some point.

Any ideas on a paint that I can use to touch up the frame? Also, it is official, I am now begging for info on the shock valving.
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1987 KDX200 resto project

Post by pumpguy »

I understand Duplicolor Grabber Green is a good match.
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Re: 1987 KDX200 resto project

Post by Goofaroo »

Thanks for the tip. However, my frame is silver.
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kawagumby
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Re: 1987 KDX200 resto project

Post by kawagumby »

I used Ford-based Dupli-Color BFM0226 silver metallic (1E) on mine.
1994 KDX200, Beta 200rr, yz125, yz250, kx100 modded for adult, gasgas contact 250.
Goofaroo
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1987 KDX200 resto project

Post by Goofaroo »

I used Ford-based Dupli-Color BFM0226 silver metallic (1E) on mine.
Was that to touch up the frame or for a total repaint? Does it more or less match the existing paint?
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kawagumby
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Re: 1987 KDX200 resto project

Post by kawagumby »

My frame paint was in pretty good shape but was dull. This paint matched well and gave it a good metallic gloss - it does not put a heavy coat on, you need more than one coat if you are trying to cover defects, and bare areas should be primed with a light grey primer.
1994 KDX200, Beta 200rr, yz125, yz250, kx100 modded for adult, gasgas contact 250.
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Re: 1987 KDX200 resto project

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Thanks for the tip. I'll give it a try.
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Re: 1987 KDX200 resto project

Post by Goofaroo »

I am about to go through the motor and I noticed that it has a 13 tooth countershaft sprocket and 48 tooth rear sprocket. Before I disassembled the bike I rode it up and down the street a bit and it sure seemed to lack any top end cruising speed. Am I correct that this is the stock gearing? Has anyone gone up a tooth or two on the countershaft? This bike will be used mostly in the woods but also for occasional fire roads and open areas. What kind of cruising speed can I expect with the stock gearing?
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kawagumby
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Re: 1987 KDX200 resto project

Post by kawagumby »

That is the stock gearing (13:48)...I put a 47 tooth on my recently rebuilt bike and I felt the 48 worked better, as it rev'd out more quickly in 6th, so I switched back. With the 47 it felt a bit sluggish in 6th. Cruising speed with stock? I dunno, but faster than an mx'r with stock gearing, for sure. Gearing it higher won't net any gain IMO -
1994 KDX200, Beta 200rr, yz125, yz250, kx100 modded for adult, gasgas contact 250.
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Re: 1987 KDX200 resto project

Post by Goofaroo »

I guess I'll just leave it like it is until we get a chance to ride it on the trail and see what happens. Riding it on the street it just didn't seem to have much of a jump from 4th to 5th and 6th like most wide ratio trannys seem to have. If we decide to dualsport this bike it'll definitely need a taller gearing configuration but for now it'll only be off road.
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Re: 1987 KDX200 resto project

Post by Goofaroo »

I pulled the top end off and it is pretty nasty. Everything is really filthy and it appears that it has never been opened up before. The piston and cylinder wall are scored badly enough that it will need to be repaired. It appears that I can just have it bored and replace the piston. Am I correct that this jug can be bored?

Any piston suggestions?
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1987 KDX200 resto project

Post by rbates9 »

A stock jug can not be bored. It needs to be replated if it is that bad. Or you could sleeve it but that is a bad idea.
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Re: 1987 KDX200 resto project

Post by Goofaroo »

I guess I'm in the market for a replacement.
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Re: 1987 KDX200 resto project

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Does anyone know of a good source for cylinder replating? How much does it cost?
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Re: 1987 KDX200 resto project

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I've done some internet research and it appears that the cheapest fix would be to sleeve the existing cyclinder. LA Sleeve will perform the work and send the jug back to me with a new sleeve, piston kit, and all required gaskets for $339. That sure seems like the easy fix. What are the downsides to sleeving as opposed to replating? According to their site, they will match and chamfer the ports and machine the head gasket surface. Sounds like a pretty solid solution unless I am missing something.

Also, while I'm at it I would like to replace the crank seals. Am I correct that this can be done wothout splitting the case?

This is going to turn out to be a pretty pricey 1987 KDX200 but I really like the bike so I want to get it right.
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1987 KDX200 resto project

Post by dfeckel »

Sadly, the cases must be split to replace the crank seals.

You are right that the sleeve service is a good deal, especially since it comes with everything to do the top end. However, an iron sleeve is not better than a good plated aluminum cylinder. It wears faster, and with each top end, you'll likely have to bore it further out and get larger replacement pistons. With a plated cylinder, as long as there is no damage, you just replace the rings and piston with the stock size. No hunting around for the correct oversize piston.

Powerseal in Pennsylvania has done a good job for me. If there are deep gouges in the the aluminum, they can simply add a little weld, machine to spec, and then plate. It should cost in the neighborhood of $300.
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Re: 1987 KDX200 resto project

Post by Roadhazardguy »

If you could get ahold of this guy he would probably sell you a cylinder for cheap. http://kdxrider.net/forums/viewtopic.php?f=69&t=12422
Tony
1988 KDX 200
1980 KD 80
1989 ATK 406
1984 RM 500
1980 KZ 1300
2008 SM450R
Goofaroo
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1987 KDX200 resto project

Post by Goofaroo »

If you could get ahold of this guy he would probably sell you a cylinder for cheap. viewtopic.php?f=69&t=12422
I replied to his thread so we'll see what happens.

I also took another look at my cylinder and it appears that a lot of the damage that I percieved is actually aluminum burned onto the cylinder wall. I am going to try some muratic acid tonight and see if maybe I can clean it up.
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Re: 1987 KDX200 resto project

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I went ahead and split the case today and it turns out that it looks like the magneto side crank seal was leaking. The crank bearings seem fine so I will just order new seals.

I took some muratic acid and ate the aluminum off of the cylinder bore and it is is much smoother but I'm not sure if I will be able to reuse it or if I need to have it sleeved or plated. I'm going to have a friend give me his opinion on the bore and start weighing my options. This is turning into a very expensive 87 KDX200.

The exhaust valve was unbelievably carboned up but still seemed to be operating smoothly but I took it all apart for a thorough cleaning. The majority of the work I'm doing is cleaning all of the parts after I remove them.
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