Dirt bike transmission gears kinda beat up. Can I run it like this?

Discussion in 'The Garage' started by TheRadBaron, Jul 16, 2017.

  1. TheRadBaron

    TheRadBaron Been here awhile

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    I bought a non-running KTM '06 200XC a few weeks ago and I've been tearing into it. I don't know anything about its maintenance history or anything.
    When I drained the gearbox oil the goo that came out wasn't confidence inspiring. There wasn't much oil in there, what was there was very dark, and one or two small metal chunks came out. There was also a lot of swarf on the magnetic drain plug. I have the cases split now and the gears don't look so great. At a quick glance everything looks fine but when you look closely lot of them have small chips and there is some galling on various teeth. Below is a picture that's representative of the whole gearbox.
    It would be big bucks to replace all the gears with new ones from KTM and I really don't have that in the budget. Some searching around online didn't turn up any used gearboxes. I'm hoping that I can get away with just cleaning everything up really well, putting it back together, using high quality gearbox oil, and changing it often. The gears still have their overall integrity, after all.
    What do you guys think? Can I get a couple more seasons out of this gearbox or is it a grenade that will be ready to go off? I'd also be interested in a good, used gearbox that would fit this bike if anyone had one. Either an XC or XC-W would be alright with me. Thanks.
    IMG_4059.JPG
    #1
  2. shovelstrokeed

    shovelstrokeed Long timer

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    If that is the worst of it, I really wouldn't sweat it. Yes, rinse everything with solvent and then lubricate with fresh, high quality gear oil and run her till she blows.
    A caveat, disassemble the shafts to get the sliding gears off and wash the innards and splines down. Same for any and all bearings. Study the bearings with great care, a strong light and a magnifier is recommended. Any visible defect is cause for replacement.
    #2
  3. gonerydin

    gonerydin Been here awhile

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    I think I would put in new bearings as long as you have it apart.


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    #3
  4. lnewqban

    lnewqban Ninjetter

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    As explained above.
    Additional thing that I would do: look closely for cracks, sharp edges and anything that looks like will beak away in the future and make it safer or smoother with a grinder, keeping the temperature as low as possible.
    Same for dogs that show an angle, indicating that they will tend to disengage under load.
    Break-in the transmission again and replace or exam the oil after the next 500 or 800 miles.
    #4
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  5. TheRadBaron

    TheRadBaron Been here awhile

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    Cool. I was planning to change the bearings out. Dressing the damage is also a good idea.
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  6. shovelstrokeed

    shovelstrokeed Long timer

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    I would stay away from power tools when dressing minor nicks and scratches. A couple of small square india stones will get the job done with little danger of cutting through the surface treatment on the gears. Just knock down the high stuff and round off anything sticking up on the tips of the gear teeth.
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  7. tntmo

    tntmo Oops, I did it again.

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    KTM loves sharing parts. I'm willing to bet if you looked up part numbers, the gears in the transmission cross reference between many two stroke and possibly some four stroke models. After you're armed with that info, some searching on Ebay may find you some reasonably priced replacement parts. Worth taking your time on, but I agree that the gears don't look terrible it would help you sleep at night knowing you replaced the worst of them.
    #7
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  8. ohgood

    ohgood Just givver tha berries !!!

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    the dogs matter a lot more than the gears. if the dogs are notched or angled, get a new (you know, eBay "new") transmission and pick the best ones to run. I'll mirror what the others said about knocking down the sharp edges and notches on the gears.

    I bet they blew up a clutch basket and kept running it, or had a bad bearing that chipped the gears.
    #8
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  9. trailer Rails

    trailer Rails Washes hands before going to the bathroom

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    That is a dirtbike he is working on, typical oil life is 1-200 miles. If you want to do a quick oil change and inspection, that would be 50 miles. Obviously that depends on where and how he is riding.
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  10. TheRadBaron

    TheRadBaron Been here awhile

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    I think I found a good used gearbox on ktmtalk. If that doesn't work out I'll just deburr and run this one assuming it holds up to a better inspection of the dogs and everything.
    #10
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  11. JCool

    JCool Long timer

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    It's a 2-stroke , therefore we're talking transmission lubrication , not a high strung , low oil capacity 4-stroke.
    #11
  12. TheRadBaron

    TheRadBaron Been here awhile

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    I still change 2-stroke gearbox oil after every couple rides. Cheap insurance.
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  13. trailer Rails

    trailer Rails Washes hands before going to the bathroom

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    Lots of clutch material becomes deposited in the oil. Obviously that depends on how and where he rides it.
    #13