1990 KTM MX 250 Built

jbrowny
Posts
4
Joined
9/7/2023
Location
Molesworth, TAS, AU
9/7/2023 3:01pm
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...
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













jbrowny wrote:

Is it possible to get in contact with you, I’m currently doing the same job, any help will be much appreciated 

Do you mean the clutch cover / water pump. I used one off a 95 those are alloy go right on. The 96/97 covers would work...

Do you mean the clutch cover / water pump. I used one off a 95 those are alloy go right on. The 96/97 covers would work. If you drill out the blocked off hose cast area. 

Then you'll have to either thread the one side to screw in a new water spigot or press fit one in. Of your own. 

Ok cool, nothing else has to be done? I noticed something about the power valve, can I still use my old one in the new case 

9/8/2023 12:51pm
jbrowny wrote:

Ok cool, nothing else has to be done? I noticed something about the power valve, can I still use my old one in the new case 

Depends which KTM you have.Mine is a 1990 Power Valve is different to 1991-1997

I have to put Shims under the Power Valve Adjuster, the 1994Aluminium Cover was a little different to the 1990 Magnesium Cover 

jbrowny
Posts
4
Joined
9/7/2023
Location
Molesworth, TAS, AU
9/9/2023 1:28am
jbrowny wrote:

Ok cool, nothing else has to be done? I noticed something about the power valve, can I still use my old one in the new case 

Depends which KTM you have.Mine is a 1990 Power Valve is different to 1991-1997 I have to put Shims under the Power Valve Adjuster, the 1994Aluminium...

Depends which KTM you have.Mine is a 1990 Power Valve is different to 1991-1997

I have to put Shims under the Power Valve Adjuster, the 1994Aluminium Cover was a little different to the 1990 Magnesium Cover 

Rightio ok, I have a 1990 and I’ve brought a 96 case with the lower power valve linkage setup

jbrowny
Posts
4
Joined
9/7/2023
Location
Molesworth, TAS, AU
9/9/2023 10:14pm
jbrowny wrote:

Ok cool, nothing else has to be done? I noticed something about the power valve, can I still use my old one in the new case 

Depends which KTM you have.Mine is a 1990 Power Valve is different to 1991-1997 I have to put Shims under the Power Valve Adjuster, the 1994Aluminium...

Depends which KTM you have.Mine is a 1990 Power Valve is different to 1991-1997

I have to put Shims under the Power Valve Adjuster, the 1994Aluminium Cover was a little different to the 1990 Magnesium Cover 

Am I able to use the 96 case and powevalve setup? I could only see the difference in the 2 springs as opposed to the “drum” and a spring setup, would that be correct? Appreciate the help 

The Shop

9/9/2023 11:57pm
jbrowny wrote:

Ok cool, nothing else has to be done? I noticed something about the power valve, can I still use my old one in the new case 

Depends which KTM you have.Mine is a 1990 Power Valve is different to 1991-1997 I have to put Shims under the Power Valve Adjuster, the 1994Aluminium...

Depends which KTM you have.Mine is a 1990 Power Valve is different to 1991-1997

I have to put Shims under the Power Valve Adjuster, the 1994Aluminium Cover was a little different to the 1990 Magnesium Cover 

jbrowny wrote:
Am I able to use the 96 case and powevalve setup? I could only see the difference in the 2 springs as opposed to the “drum”...

Am I able to use the 96 case and powevalve setup? I could only see the difference in the 2 springs as opposed to the “drum” and a spring setup, would that be correct? Appreciate the help 

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As i remember the right is a 1990 the left a 1991>onwards 

You have to measure from the Clutch Cover sealing surface down to the Waterpump Bearing, there was 1Milimeter difference from Aluminium to Magnesium Cover 

Lrain4546
Posts
1
Joined
1/9/2026
Location
Nevada, MO, USA
1/9/2026 5:15am
Still waiting for some Graphics hope can finish that Projekt next week         

Still waiting for some Graphics hope can finish that Projekt next week 

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7B836835-D696-4208-80E5-D10B1EBD0291.jpeg?VersionId=j9SWLGPl7xRuj4bQ.3Fz7D

D5420B3A-7A3B-46DE-A75C-1A2A5D4619F6

 DA08D6A1-0BF3-4FBC-A7D4-442F162F1B5E

 

Hey bud, I just picked up a ‘90 KTM 250 MX yesterday but don’t know much about it and I’m not sure on what parts are interchangeable through the years. Could I get some help pls? From my understanding, from ‘90 to ‘94 a lot of the parts are interchangeable but I’m not 100 % sure. 

1/11/2026 7:39am
Lrain4546 wrote:
Hey bud, I just picked up a ‘90 KTM 250 MX yesterday but don’t know much about it and I’m not sure on what parts are...

Hey bud, I just picked up a ‘90 KTM 250 MX yesterday but don’t know much about it and I’m not sure on what parts are interchangeable through the years. Could I get some help pls? From my understanding, from ‘90 to ‘94 a lot of the parts are interchangeable but I’m not 100 % sure. 

Hello, the 1990 Engine is Special it’s the First year of the 546 Engine Type 

Kickstart-Clutch- Pover Valve and i think Main Bearings are different to 1991 

1
JoWe
Posts
2
Joined
1/11/2026
Location
MUC, DE
1/11/2026 9:05am

Hallo KTM Two Stroke, ich habe gerade deine ganze Storry gelesen. Hut ab, es ist der Wahnsinn wieviel du in Details gesteckt hast, deine KTM ist Hammer! Ich würde dir gerne eine PM schreiben, bin aus dem Raum MUC und ebenfalls Besitzer einer 90er. Vielleicht kannst du mich kontaktieren. Beste Grüße Jo

1/11/2026 11:42am
JoWe wrote:
Hallo KTM Two Stroke, ich habe gerade deine ganze Storry gelesen. Hut ab, es ist der Wahnsinn wieviel du in Details gesteckt hast, deine KTM ist...

Hallo KTM Two Stroke, ich habe gerade deine ganze Storry gelesen. Hut ab, es ist der Wahnsinn wieviel du in Details gesteckt hast, deine KTM ist Hammer! Ich würde dir gerne eine PM schreiben, bin aus dem Raum MUC und ebenfalls Besitzer einer 90er. Vielleicht kannst du mich kontaktieren. Beste Grüße Jo

Servus kein Problem schick mir eine Nachricht 

JoWe
Posts
2
Joined
1/11/2026
Location
MUC, DE
1/11/2026 12:34pm

Servus, 

Das würde ich gerne nur kommt die Meldung: Sorry, this user is not accepting private messages.

Ich bin immer noch ganz baff von deinem tollen Aufbau und stell mir nun die Frage ob ich ein Fehler gemacht habe mit dem 90er Modell. :-/

1/11/2026 12:44pm
JoWe wrote:
Servus, Das würde ich gerne nur kommt die Meldung: Sorry, this user is not accepting private messages.Ich bin immer noch ganz baff von deinem tollen Aufbau und...

Servus, 

Das würde ich gerne nur kommt die Meldung: Sorry, this user is not accepting private messages.

Ich bin immer noch ganz baff von deinem tollen Aufbau und stell mir nun die Frage ob ich ein Fehler gemacht habe mit dem 90er Modell. :-/

Versuch nochmal, müsste jetzt funktionieren 

randbagger
Posts
123
Joined
5/17/2022
Location
Costa Mesa, CA, USA
7/28/2026 9:12am

Hello, I was the proud owner of a 1991 300 MXC. Some of the best days and some of the worst. Several times it just stopped. Pulled, pushed, kicked nothing. The next day 1st kick. Power valve. 3 times piston hit powervalve. Flapper broke off. Piston ring groove damaged. Motor was always operational. Broken piece bounced around in the pipe. Last time raced the bike the day after the valve broke. Did not remove the broken bit until after. I cracked the fork axel clamp. It was welded. Never an issue. Inconsistent running. Day to day. Temp to temp. Altitude to altitude. Never got to change the ignition. Always worked really hard on pressure testing the motor. The powervalve will leak but nothing more than micro scopic foam anywhere else. I used Hondabond 4 (unique Silicone product) to smear all paper gaskets and ignition manifold. 

Good luck on all your projects. 

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