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Thread: 1998 KTM 50 MINI ADVENTURE (Start with clutch)

  1. #1


    Hey guys, bought my son a 98 KTM 50 and doing some maintence along with new clutch springs to find a 3 shoe clutch?!?!? That is great because I can adjust where it engages but the clutch does not quite fit the hub. It sticks out a few millimeters and leads to some unusual wear. The hub and pads are shot so I am looking to replace both. Can I use the 3 shoe clutch hub in my 98 motor? The only thing I have noticed is that really concerns me is the fact that the gears machined on the back are at slight angles to the shaft. The 3 shoe clutch looks parallel with it. If anybody knows where to go or who to talk to I would really appreciate it.

    FMF states that their pipe works for 50cc KTM models down to 2001, I check the parts catalog and found that the 98 has the same part number as the 01, it only varies with SR, JR, and Adv models (I am assuming relating to preformance). Has anybody tried to install an FMF pipe and silencer on the 98s (any model)?

    Besides the pipe the other defining feature between the models was the carb, can I swap the DelOrto for the larger SR carb?
    Also looking at the Delta V reeds, can that be done?

    Bought this bike for $300 on craigslist so I am really stoked to get my son off his '81 PW50, the suspension was the best part but now he needs the the power. 4 y/o loves to ride, still on TW but can do some pretty sketchy trail riding. Can't afford the newer $2000 bikes so this will have to make do for awhile.

    Can anybody link me to the dominator clutch kits for this year? I figure it is better to buy an older bike and upgrade then new and be stuck with stock.

    Next is suspension...

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  3. #2


    Clutch Hub Dimensions
    this is ruff measurements of my sons clutch. I measured btwn 3 to 6 places and took the mean value as true, nothing was off more then about 0.1 mm.

    Will also say that the clutch and hub need to be replaced. Also the springs where installed completely wrong! as you can see in one picture the shoe would drop a good 3 to 4 mm before resting on the bolt (PIC 2, the bolt is IN the shoe)... this explains it severe crawl even at idol and bogging at low speeds in inclines, soft dirt, or if he came to a stop. Also you can see that since there was no washer btwn the hub and clutch that she was always rubbing on the back (front of the hub). Also the clutch stick out slightly (pic is without washer!)

    Once this thread has some support I will see if I can post a KTM 50 Morini Bible

    90.00 mm - 90.04 mm

    internal diameter
    84.4 mm

    hub wall thickness
    2.84 mm

    internal shaft diameter
    15.06 mm

    gear diameter
    33.4 mm

    hud depth
    20.85 mm

    overall depth
    37.5 mm

    PIC #1 user posted imagestock hub '98, seeing the back, which faces the engine when installed. Only see once it has been pulled off, notice the machined gears are not running parallel with the crankshaft it sits on.

    PIC #2 user posted imageThis is the photo showing the free play with THE BOLT IN!!! No wonder the bike could not sit still or hit the power band

    PIC #3 user posted imageNotice the shoe's pad wear on the left (well the far left edge has none ha ha). This is because the pad sticks out slightly (PIC 5) The wear is very uneven.

    PIC #4 user posted imageThis is inside the clutch hub where the shoe comes in contact with the hub. Those brown lines are not dirty oil, the the hub literally has to rings where no (or close to it) wear has occurred. That is the same color as the back of the hub. This is from the gaps between the contact "patches".

    PIC#5 user posted imageThis shows the 3 shoe clutch inside the stock hub. Notice that the clutch is a mm or so thicker then the hub's wall or drum surface. This is by the way without a washer btwn the hub and clutch.

    PIC #6 user posted imageA front view of the clutch inside the hub. Notice that the shoe walls are showing wear from lack of a washer separating from the hub's front face. Also you can tell I have it backwards (clutch assembly) because you can see the tapper which is pressed onto the crank

  4. #3


    Here is the KTM '98 50 Mini Adventure Clutch Removal Procedure

    Will post complete bike project in few days hopefully including engine removal and case removal for anybody interested. It was all pretty easy.
    This should work for at least models years 97 to 01. The only differences where minor like carbs, pipe, and reeds however the engines are VERY similar. Please ask if you have a specific concern. I am not a KTM mechanic so please verify before taking my process into action. I used the 97 engine manual as reference. Will say a little disappointed in quality for $38 but it was all I can find. Yes I have a 98 MA but the manual looks identical to my engine, not sure how NCY order the wrong year but whatever:smirk:

    Starting here
    I have the clutch cover and gasket removed along with the engine pulled out of the chassis. I kept the bolts in their respective holes to make sure I don't loose anything or spend an extra 10 minutes trying to figure which one goes where.:banghead: When this is down you should have a similar scene on the work bench (or old desk if you run a little redneck:banana

    user posted image
    yes the screw driver is intentional
    Insert the screw drive into the holes between each shoe,
    user posted image into the holes in the hub

    into the driven internal gear to hold it still while you break the nut (hopefully not literally)

    user posted image

  5. #4


    Once you have the nut off it should look something like this...
    user posted image
    Yes it may look like one piece but I promise it is a nut:thumbsup: Notice the machined surfaces, use a 15 mm open ended wrench to break the nut AGAIN IT LOOKS LIKE A GEAR!!!! AND IT IS LEFT HAND THREAD, my tools learned the hard way... don't ask:doh:

    Next you will need a special tool to pull it the clutch shoe off


    Bought mine off ebay for $30 with free shipping, made in the USA, worked great
    user posted imageused a 19 mm closed end wrench to drive the press (the large hex head in the center)

    In this photo I show with the clutch already out in case you are not real familiar with these tools. You simply screw the threaded bolts on each side into the tapped holes around the center of the clutch assembly. Once they are in hand tight (close to touching bottom) make sure they are close to level as possible to better distribute force between the two screws. Next torque the press bolt down until the clutch 'pops" off, it will pop. For really stubborn assemblies use a little heat with a torch. If you are unsure how to do this, get somebody familiar with the process. Evenly heating and not allowing the flame to sit at one spot are critical!
    user posted image this is using the 4 mm allen to screw in the side bolts. My allen wrench is just designed to be used with a ratchet (great tool). Again the clutch is out just so it is easy to see what I am doing

    nextuser posted image thread the press bolt (large center bolt) into the press body apply the force to the crankshaft arm, what the clutch sits on. This time I show the actual set up to pull it off its shaft. Your set up should look similar to this photo. Keep twisting the wrench on the press bolt until the clutch breaks free, again it will "pop" off. If you are applying an absurd amount of force then double check everything is right. Not worth breaking parts.

    user posted imagehere you can see the press bolt's contact tip meeting up with the shaft to apply pressure against the crankshaft resulting in pulling the smaller side screws away from the engine

    POP:banana:user posted image pull it out to inspect the shoes, the hub and make adjustments or replacement as

    user posted image

    The hub can be pulled off by hand now, looks like

    user posted image

  6. #5


    sweet, now to adjust the clutch stacks or springs.
    The springs come on the MINI ADVENTURE clutch but you can add a washer or two to boost the "hit" and get the bike to rev high before it engages. The washer stacks are for the JR and SR bikes but any can be interchanged based on the rider. Springs are recomened for beginner to intermediate riders or tight/root conditions. Stacks can be adjusted all the way to extreme hits for advanced riders competing in mx races. I suggest visiting the KTM 50 bible for way more info form the experts. You can request the use of a free emails if that has been a problem for your reg in the past:thumbsup:

    Again the stacks where wrong in my son's bike resulting at crawling during idol and bog at slow speeds, just showing you how to get to the bolts where the springs or stacks go.

    user posted imageuse a 10 mm socket to remove the shoes.user posted image once the bolt is out you can remove that shoeuser posted image now take out the bolt and look at the current configuration. user posted imageOn the stacks you have washers which are slightly cupped and shims. The way these are stack is a matter of debate and so is the suggested number again you would have to see the suggestions of KTMtalk. I can ask if they will let me post that info but must have permission (just joined, don't need a suspension already, I reserve that privilage for Ud right here on TT:devil::busted A big key is clean them and use loctite once reinstalled.user posted image
    Here they are removed to show you the difference between the washers and shims, not sure what that start washer is for any ideas?

    Yes the trans fluid was that dirty, guess I will have to tell my wife we just have to rebuild and mod

    Let me know if I missed anything or you have questions, will post torque specs soon, 7ftlbs for the stacks, keep really close to that for consistent performancerof:

  7. #6

    Default Re: 1998 KTM 50 MINI ADVENTURE (Start with clutch)

    We’re you successful with this clutch mod? I have the 2 shoe and would also like to switch to the 3 shoe.

    Thanks for any help!

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