1990 KTM MX 250 Built

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4/2/2022 12:46 PM

After a long Research i found a 1990 250 MX .
Visual in a Good Condition with New Plastic and Graphics -Powdercoatet Frame.
Seller wants 3000€ i give him 2000€ , it’s still to much but that bikes are very Rare i drive 1500 Kilometers .

But technical really bad. Engine needs a complete Rebuilt, Swingarm -Linkeage -Wheelbearings are Toast, Fork lost Oil

These Is Not the Problem i found Piston, Connecting Rods , Bearings and Gasket kits.
What concerned me is the inner Clutch Cover it’s complete rotten and lost Water

If anybody has experience/useful Infos with these bikes please let me know

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4/2/2022 12:47 PM

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4/2/2022 12:50 PM

Start disassembling today

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4/2/2022 3:06 PM

Looks like a magnesium clutch/ water pump cover. Just like the Honda”s, over time they rot. Highly doubtful anyone is making replacement covers for these bikes as the production numbers were likely low. You have 2 options. 1. Located an NOS cover or 2. Repair what you have. Hard to tell how bad your cover is but they can be repaired with a liquid metal product if prepped correctly.

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4/2/2022 9:27 PM

I gota 91 ktm 300 last year going to restore
Lots of info on ktmtalk.com

90 - 97 covers will fit

90 - 95 magnesium
96 97 alloy

In order to use the 96 97 cover with earlier models
Must drill bore out blanked off water spigot on clutch cover. Thread it and put a water spigot in it.

Pic shows on this 96 year cover the blanked off water spigot.

There's more you can do like update the sem ignition to a newer gen bike Japanese kokousan stator flywheel wiring harness and cdi.
Foot pegs up to '16 fit.

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4/2/2022 10:26 PM

SmokinJoe439 wrote:

I gota 91 ktm 300 last year going to restore
Lots of info on ktmtalk.com

90 - 97 covers will fit

90 - 95 magnesium
96 97 ...more

Thanks for that information was not sure about the newer Clutch Cover they look similar but Part Numbers are different

But when I can modify a 96-97 i try to find one

The next problem is that bike was convertet from a GS to MX and acorrding to KTM Parts list there are some differences



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4/2/2022 10:31 PM

sandman768 wrote:

Looks like a magnesium clutch/ water pump cover. Just like the Honda”s, over time they rot. Highly doubtful anyone is making ...more

It’s really in bad Condition

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4/3/2022 7:43 PM

I found a pic of oneof the newer 96 97 alloy covers modded so you can better see it. Did mention a couple things I forgot. Newer cover has 1 extra bolt hole mounting point around kickstarter that doesn't effect anything. Rubber piece for power valve linkage must use older style. Older style round newer style squared shaped.

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4/4/2022 3:14 AM

Ok now I see what you mean
Is that water Connector removeable from the old cover
What Size of Thread is it ?

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4/5/2022 9:41 PM

KTM Two Stroke wrote:

Ok now I see what you mean
Is that water Connector removeable from the old cover
What Size of Thread is it ?

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Don't know just saw that was the fix size n thread may depend on what you do. Water spigot not sure have to make your own.

Think it maybe cast as part of the case not removable. I can't tell you that yet I haven't started on mine. Been mostly gathering info on what swaps upgrades I can do. I'm not going to keep my 91 300 original.

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4/6/2022 6:54 AM

You have got a gem there mate .... good luck with the build... cool

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4/11/2022 4:51 AM

Split the Cases this Weekend with a selfmade dissasembly Tool
Lukily the gearbox is ok the rest is toast , never seen Main Bearings like this
Now sent out Crankshaft for service and look for Engine Bearings and Piston

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7/3/2022 2:51 PM

Small update on my 250 MX Built
Almost every part on that bike was broken
Swingarm Crack
Inner Clutch Cover Magnesium rotten
Outer Clutch Cover Crack
Front Wheel Bearings
Carburetor Coating comes off
Linkeage completely rotten
Clutch Basket worn out

Biggest Challenge was to find parts because the 1990 was the first Model of the 546 Engine Type and KTM change many Parts in 1991


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7/3/2022 2:59 PM

Almost 3 Month and 3000€ later 😂 I had almost every part for the Rebuild
Engine was out for Cleaning and some Repair Welding

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7/4/2022 10:28 AM

god damn that motor looks good, vapor blasted?

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7/4/2022 11:41 AM

Hope I can translate it right from German but I think you call it Glass Bead blasting
Very good looking but
the Problem was i covered every hole with Tape but the glass dust come everywhere inside the engine

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7/4/2022 1:25 PM

KTM Two Stroke wrote:

Hope I can translate it right from German but I think you call it Glass Bead blasting
Very good looking but
the Problem was ...more

Nice rebuild I'm about to start a 91 300 exc I'm going to make into a 93 300sx.

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7/4/2022 2:52 PM

KTM Two Stroke wrote:

Hope I can translate it right from German but I think you call it Glass Bead blasting
Very good looking but
the Problem was ...more

SmokinJoe439 wrote:

Nice rebuild I'm about to start a 91 300 exc I'm going to make into a 93 300sx.

I think the 1991 is a good bike for rebuild you can interchange many engine parts from 1991-1996
Like Clutch-Cylinder-Power Valve and many Chassis Parts are the Same

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7/4/2022 7:14 PM

KTM Two Stroke wrote:

Hope I can translate it right from German but I think you call it Glass Bead blasting
Very good looking but
the Problem was ...more

SmokinJoe439 wrote:

Nice rebuild I'm about to start a 91 300 exc I'm going to make into a 93 300sx.

KTM Two Stroke wrote:

I think the 1991 is a good bike for rebuild you can interchange many engine parts from 1991-1996
Like Clutch-Cylinder-Power ...more

Those clutch basket dampers

Where did you get them still available new from ktm?

I haven't done anything to mine yet just a lot of parts swapping research on it.
So far all I've done is buy a 93 sx 250 petrol tank and subframe airbox.

I bought a new air boot for the air box from enduro klassiker. When I got it, it looked like a cr250 part.
The air filter cage and air filter are 98 cr250 fit.

I'm also going to do the cdi ignition wiring swap to the kokusan from a later model. Seen a couple swaps done last one guy was using a 2017 300 cdi.

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7/4/2022 9:18 PM

SmokinJoe439 wrote:

Nice rebuild I'm about to start a 91 300 exc I'm going to make into a 93 300sx.

KTM Two Stroke wrote:

I think the 1991 is a good bike for rebuild you can interchange many engine parts from 1991-1996
Like Clutch-Cylinder-Power ...more

SmokinJoe439 wrote:

Those clutch basket dampers

Where did you get them still available new from ktm?

I haven't done anything to mine yet just ...more

Almost every Spare Part I get from André Horvath
Enduro Klassiker , I’m lucky he is close to me I visit him many times for that project to find out the right parts also the Clutch Rubber Dampers

KTM Musch in Germany is a Good Adress for Youngtimer parts but the are expensive

What I can recommend is a Talon Clutch Basket they use Srews for the Gear and not the Rivets

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7/5/2022 12:47 AM

A very nice build! I´m excited about the result.
best regards from Germany
Jonathan

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7/5/2022 1:08 AM

Jonathan83 wrote:

A very nice build! Im excited about the result.
best regards from Germany
Jonathan

Thank you Its a lot of work to finish but time is rare at the moment.
Planed some Powdercoating for the brake caliper and Hubs to match the blood red from the frame and maybe New Rims

Grüße zurück aus Österreich

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7/14/2022 11:26 AM

Pick up some Graphics and Seat Cover today in Italy 🇮🇹


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7/24/2022 10:20 PM

New Billet Clutch Cover

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8/4/2022 6:52 AM

Nice bike I just recently picked up a 91 KTM 300. Was told by the guy selling it that he didn't know much about it just that he got it at a estate auction. But he thought it was a 125. So I went to look at it and once I saw the pipe and cylinder I knew it was no 125. He was asking $400 but I talked him down to $200. Has good compression but he flywheel is gone. I read something about these bikes having bad ignition systems. But that they can be retrofitted with stuff from a newer model. Mine needs a total rebuild too it's been rode hard and put away wet. And from the look of the plastics it's spent a few years outside.

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8/4/2022 9:52 PM

Vogel174 wrote:

Nice bike I just recently picked up a 91 KTM 300. Was told by the guy selling it that he didn't know much about it just that ...more

The 1991 is a better bike to start a rebuild it is the second year Generation of the 546 Type Engine

It think it already have the Aluminium inner Clutch Cover, it has updated Clutch Hub and Disc wich is the same til 1997

About the Ignition i have the old SEM and it works but think about a upgrade when its completely finished

Good luck for your Build

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