1990 Rebuild/Restoration - A Family Heirloom

Discussion specific to the 1989 - 1994 (E Series) KDX200 model sold in the USA
Post Reply
Drunkonunleaded
Member
Posts: 7
Joined: 11:01 pm Jul 19 2020
Country: United States

1990 Rebuild/Restoration - A Family Heirloom

Post by Drunkonunleaded »

Stealing this first post from my intro thread...

I've recently come into possession of a 1990 KDX 200. The bike was purchased new by my uncle in 91, and saw a lot of trail riding. For a few years, he rode it in some AMA D-14 events, including a few rounds at the Silverdome. In the early 2000s, he switched to quads and it mostly sat in the shed at our property in northern MI.

This weekend, a deal was struck and I bought it home.

For the most part, the bike is in great shape aesthetically. Most everything on the bike is original, sans the silencer and handlebars.

Mechanically, she hasn't fared as well unfortunately. While most of the bearings seem to be in good shape, everything rubber is about shot. The teardown and "restoration" will be cataloged in this thread. F

To start things off, here's a few quick photos from before I began to tear things apart:

Image

Image
Drunkonunleaded
Member
Posts: 7
Joined: 11:01 pm Jul 19 2020
Country: United States

Re: 1990 Rebuild/Restoration - A Family Heirloom

Post by Drunkonunleaded »

After getting this thing back home, I begin to take stock of the situation. Sorry, I did not think to take pictures during the initial assessment, but I have plenty of the teardown which will be highlighted later in this thread.

Here's the major items that will need addressed:

1) Brakes. Complete garbage. Brake fluid is clean, but who knows when it was last replaced. All dust seals are falling apart. Rotors are rusty.

2) Engine. Was originally "stuck" when I picked it up. A swift kick loosened it up. Bike has never had a top end rebuild and the carb was on stock jetting. This thing is about as stock as it gets (minus the FMF silencer as the original got damaged). The fuel lines are crumbling and the vent hoses are hard as a rock. Carb will need a rebuild at a minimum. Splitting the cases is highly unlikely.

3) Cooling system.. Coolant is clean, but has NEVER been changed. Radiators are nearly undamaged, with few bent fins. Almost zero scale buildup inside.

4) Gearbox. Too early to tell. This was one of the few items that saw regular service. Then again, there is little to go majorly long here. Chain and sprockets are greasy. Wear does not seem abnormal.

5) Suspension. Seemingly fine. No idea when stem or linkage bearings were last serviced. Assuming never. That being said, everything is smooth. I am much larger than my uncle, so while this bike was set right for his 5'7"(?) 180lb frame, this setup isn't going to cut it for a 6'4", 280lb. freak of nature like myself.

6) Wheels and Tires. This thing is supposedly on it's original tires... Seriously. No dry rot, but they're hard as a rock. Wheels are true and have no cracks. Spoke are corroded, but the bearings are good.

7) Aesthetics. Everything is in excellent shape. Some minor scuffs (as is expected) and scraped graphics, but nothing needs replacing other than a ton of rusty hardware. Odometer cable snapped, but I believe the head unit itself is still functional. Seat foam has been "reshaped" (albeit poorly).

With that being said, the question becomes: How do we address the above?
Drunkonunleaded
Member
Posts: 7
Joined: 11:01 pm Jul 19 2020
Country: United States

Re: 1990 Rebuild/Restoration - A Family Heirloom

Post by Drunkonunleaded »

So with the above issues in mind, it is time to decide what path we are going to take. To be honest, my first thought was to use the engine/gearbox and build a KX Hybrid. This would net me a "modern" bike with the sweet E-Series powerplant. If I could come up with an "ideal" trail 2020, that is close to it.

On the other hand, this is not some Craigslist basket case. People have sentimental attachments to things, and I can vividly recall my first experience riding this thing. It's simply too nice of a bike to cut up or part out.

That leaves us with two viable options: Leave as a survivor, or "reimagine" this bike as something different. I could simply address the brake hydraulics, attempt to scotchbrite the rotors, rebuild the carb, and more or less have a perfectly functional bike. Or, I could address the known issues

The other option is to replace, but upgrade. This mainly applies to the front end. Is swapping to something like a more modern KX USD fork setup a big upgrade? My thought process was that if I am truly going to ride this thing, I will need a fork rebuild at a minimum. Couple that with the possibility of not being able to salvage the $100 stock front rotor, and the rest of the braking system needing a refresh, I might as well spend the extra $300 or so on modern forks and brakes (CRF or similar per some other threads here). If I'm going to go this far, I'd probably look at upgrading a few other things, kind of blending the original 90s aesthetics with a more modern "works" feel.

It was my thought that the upgrade path, while a bit more expensive, might provide for a better riding bike. If I do ever decide to sell, something like a fork upgrade seems like the type of reversible mod that could add value (to an extent) for someone who is looking for a solid bike to ride. My problem is that I am almost of the opinion that this thing is closer to a good vintage "rider" and not something that's going to see Harescrambles or the track any longer. I am open to people's input on this topic, however.
Drunkonunleaded
Member
Posts: 7
Joined: 11:01 pm Jul 19 2020
Country: United States

Re: 1990 Rebuild/Restoration - A Family Heirloom

Post by Drunkonunleaded »

The way forward...

This is where I tap into the wealth of knowledge here on the forum. For the most part, I've been able to search and find the answers I've needed. For some other items, I have yet to find a clear answer. More importantly, I love the idea of active forums and wish to contribute to a community of enthusiasts vs. simply posting questions on a Facebook group. With that being said, this is my gameplan so far:

1) Brakes. Rebuild master cylinders and calipers using an All Balls kit (or similar). Attempt to clean rotors via scotchbrite pads or perhaps electrolysis. If unable to save them, investigate alternatives via parts swap. Later E-Series rotors are available, but early ones are not. Basic sintered pads (Tusk, EBC, or similar) to get things rolling. The hoses look to be in good shape, but I'd prefer to replace them. My plan temporarily is to address the other items (rotors first, then master/caliper rebuilds). If everything is good with the other items and I stay stock, I will try to track down new hoses.

2) Engine. Carb rebuilding seems straightforward, but the art of jetting is voodoo to me. Should I go with FRP's recommended jet/needle settings and piece together a kit from Sudco, or simply go with a generic Moose/Tusk rebuild kit and go from there once it gets running? Fuel lines are 1/4" ID and vents are 1/8" ID (correct me if I'm wrong...), I will be replacing all of it. Also plan on replacing the reeds while I'm in there. Not sure if it's worth going with the Pro Series carbon reeds if I don't plan on doing major engine mods at this point, but it can't hurt, right? I also plan to repack the silencer. A pipe would be nice, but not needed to get it going.. That would be considered "Stage 2" engine mods.

3) Cooling system.. Coolant is clean, but has NEVER been changed. This is an easy one. Fresh coolant + hoses. From what I gather, the GPI silicone hoses for the H Series can be made to fit with some trimming.

4) Gearbox. Change the fluid with Golden Spectro 10W-40 and degrease the chain and sprockets. Re-address this area if needed.

5) Suspension. Still debating on doing the fork conversion vs. rolling as while I address the other areas. Kind of depends upon the investment required as far as saving the OE front brake rotor. Otherwise, I don't plan on touching anything until the first shakedown ride around the yard. I'd prefer to know that it's running before address a mechanically functional system.

With that being said, this thing is going to need to be resprung for my weight regardless. I've noticed various labor rates for a rebuild, but I am ignorant of bike suspension. On a car, you typically have to revalve your dampers when moving up in spring rate. Should I be budgeting for revalving too, or is this a case of paying someone to throw in new springs, seals, and oil? Regardless of whether I go to a modern fork or keep the stock setup, I will have to respring as mentioned previously.

6) Wheels and Tires. Plan to leave as-is until I can address the engine and sort out the brake issue. If going to a KX setup, I'd likely rebuild the rear wheel with stainless spokes. Once I get a path set and know the engine is good, I'll eventually replace the hub bearings just so that everything is 110% new.

7) Aesthetics. Planning on polishing the plastic. Debating whether leaving the stock graphics as is (see pics in following post), or getting a set of reproduction OEM shroud graphics. This, again, is all secondary to getting it rideable. If I decide to head down the "upgrade" path with the KX forks and whatnot, I've had an idea in my head of going full out with Splitfire graphics or similar with a more modern ribbed/gripper seat cover.

However, I do plan on addressing some issues during the teardown. While it is apart, I also plan on using PJ1 paint to touch up the frame. While it obviously won't be perfect, I'd like to address any potential problem areas before rust begins on the frame. I hate garbage fasteners, and plan on throwing in new hardware in most places, from Specbolt or similar. I'd like to find a good piece of seat foam without having to spend $100 on a new hunk of foam from CEET.
Last edited by Drunkonunleaded on 12:20 am Jul 21 2020, edited 1 time in total.
Drunkonunleaded
Member
Posts: 7
Joined: 11:01 pm Jul 19 2020
Country: United States

Re: 1990 Rebuild/Restoration - A Family Heirloom

Post by Drunkonunleaded »

Now that we've addressed the background and what needs addressed, it's time for everyone's favorite part: pictures! Here's a few snaps from the initial steps of teardown. Do note that this bike hasn't been cleaned in ages. I'd venture to guess that this is the first time that a lot of these items have been removed.

Image

Ignore the messy garage, I just completed a move and am still getting settled into the new digs. This is how the bike looked after a 300 mile ride home on a rainy Sunday afternoon.

Image

I first pulled the side covers. Nothing bad under here, just a lot of dirt. This looks to be an OG Powercore? I haven't seen one like this before with a ribbed case.

Image

Not much going on under those side covers. Just a lot of old dirt.

Image

There was quite a bit of dirt/grease buildup here. Not pictured: a colony of ants living behind the headlight bulb. Apparently, a group of ants decided to hide their eggs back there. They were not a fan of getting blasted by brake cleaner...

Image

That's not rust, it's actually more dirt. There is some rust where the upper shock mount is welded in (bottom of photo), but it's only on the surface. I plan on addressing these areas with some PJ1 paint and rust converter primer.

Image

Dirt under the tank.

Next steps are to continue the teardown, cataloging items which may need replaced. I plan to next address the engine and cooling system, with some input from the hive mind here. Goal is to rebuild the carb, throw on new reeds, and address the fuel/vent lines. I'll likely pick up a new radiator cap as well. Is the OEM one the way to go, or is there a preferred alternative? I prefer OE quality or better here, but if there's a generic (like Gates or similar) or upgrade to be hand, I am open to any and all suggestions.
User avatar
jaywylie
Supporting Member I
Supporting Member I
Posts: 93
Joined: 09:35 am Jul 23 2013
Country: USA
Location: New Orleans
Contact:

Re: 1990 Rebuild/Restoration - A Family Heirloom

Post by jaywylie »

This is so cool. What a great backstory! If it was mine, I'd try to restore rather than upgrade wherever possible and keep this bike a time capsule. Some items, like suspension, just may not work for you. In that case I'd keep all the original parts to be able to return to stock, but upgrade for function's sake.

Thanks for the great write up!
User avatar
KDXGarage
KDXRider.net
KDXRider.net
Posts: 14047
Joined: 06:45 am Nov 01 2004
Country: United States of America
Location: AL, USA
Contact:

Re: 1990 Rebuild/Restoration - A Family Heirloom

Post by KDXGarage »

How did I miss this one?? Thank you to jaywylie for bringing it back up.

Clean, clean and clean. Try to hold off on the break cleaner as a general cleaner. It's a bit harsh for most things.

The spark arrestor is indeed an old model. Mine is the same on my '94.

Looks good!
Thank you for participating on kdxrider.net. :bravo:
To post pictures from a device: viewtopic.php?f=88&t=24128
sluggo641
Member
Posts: 5
Joined: 09:53 am May 30 2021
Country: United States

Re: 1990 Rebuild/Restoration - A Family Heirloom

Post by sluggo641 »

is this bike going to be for sale? :pop:
Post Reply