2 stroke fouls plugs quickly

Discussion in '2 smokers' started by Stick_man, Jul 31, 2020.

  1. Stick_man

    Stick_man Adventurer

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    75 Harley sx 175

    I rebuilt it recently and replaced 2 broken gears. Upon rebuild I noticed the clutch wobbled a little. Anyway the plug fouls quickly and bike smokes like a b*tch. I replaced the right seal so I don’t know how gear oil is going in. Unless the gasket between the cases is bad or wobbly clutch /bad bearing is causing the seal to not work ... how else is oil getting in there? The trans oil is low so I know it’s going in
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  2. motu

    motu Loose Pre Unit

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    I'm not familiar with the engine, but on some 2 strokes the right hand main is lubed by the gearbox oil, and so the seal is inboard of the bearing, a leaking seal will suck gearoil into the crankcase. But you say you've replaced the seal ? Put gear oil in the gearbox, you'll smell it in the exhaust to confirm.
    #2
  3. Stick_man

    Stick_man Adventurer

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    It’s a typical Japan two stroke set up. The main bearings are lubed by 2 stroke oil injected in the cyl head.

    And yes I did replace the seal - it still does it. Did you mean put2 stroke oil in the gearbox ??? The gearbox already has gearbox oil.
    #3
  4. Navin

    Navin Long timer

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    Wear on the shaft? Bearings wobbling isnt going to help. Like my old 2t Derbi, fun old bikes but dont ride it farther than you can push it home just in case. :lol3
    #4
  5. Beezer

    Beezer Long timer Supporter

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    if its pulling gear oil in, it has to be either the gasket or a crack in the case
    #5
  6. BikePilot

    BikePilot Long timer

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    On a typical Japanese two stroke as you mentioned there only way for oil to get in there is the right side crank seal or leaking center case gasket.
    #6
  7. Stick_man

    Stick_man Adventurer

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    The gasket is new unless something happened to it upon assembly. Which is highly possible since I didn’t use gasket goop (I always considered it amateur thing to do). But man ripping that whole thing apart again shoot.

    Can you just run the injector Pump dry and put 2 stroke oil in the gear box or just use like castor oil or something for the gears?
    #7
  8. Strong Bad

    Strong Bad Former World's Foremost Authority Supporter

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    Let us know how that works out!
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    sieg likes this.
  9. Spikester300

    Spikester300 Roll Tide!

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    gear oil lubes the gears unless the crank seal is bad, it's not a 4-stroke.
    #9
  10. Stick_man

    Stick_man Adventurer

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    hmm the right side oil seal. OK when I put it together - I never replaced it. It started doing the oil thing in the exhaust/smoking thing. So I figured "well it has to be the seal. you should have replaced while you were in there... oh well, better late than never. " So i opened up the right side again, and replaced it with a new seal. It still does it.

    Maybe that clutch that wobbles, is causing so much vibration on the main crank it is shaking the seal that all gets past there >>> :dunno
    #10
  11. TNWillie

    TNWillie Long timer

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    Back in HS, MANY decades ago, I had a Suzuki X6 Hustler that I'd bought used. It fouled plugs in the same manner as your bike does. I rebuilt the top end (ie. pistons and rings) but it still fouled plugs. Finally sold it to a good friend who figured out the cause of the problem. I'd put std sized pistons and rings in not knowing that the previous owner had bored the cylinders 1st over. LOL
    #11
  12. Pendragon5

    Pendragon5 Carress of Steel

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    Is there an o-ring as well as a seal on the crank side?
    #12
  13. Stick_man

    Stick_man Adventurer

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    No there is no o ring. I already tore it down again. This time I am replacing all the bearings, seals, and I have a spare used countershaft. I am also using gasket goop on the center gasket and freezing the one case half before assembly. Heck I might even bring it to a mechanic and pay his 250 bucks to put it together if I have a hint of doubt about it working
    #13
  14. concours

    concours WFO for 48 years

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    ...except it’s Italian.
    #14
  15. PSchrauber

    PSchrauber Long timer

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    What color had the plugs whee they wet or just dark, or with build up black carbon?
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  16. gmk999

    gmk999 ____ as a Rotax

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    Check the cylinder bore vs the piston and ring diameter.. If its a Harley, it was owned by a Harley guy.
    Were there any homemade parts in there when you first cracked the case?:rofl
    #16
  17. Stick_man

    Stick_man Adventurer

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    I know it Italian but it resembles a typical japanese 2 stroke set up. only difference is the clutch.

    plugs are wet and black

    I think rings and stuff are ok. Has like 140 lbs of pressure.

    I think it was that center gasket ... I slit the cases and it looked like it got bunched up in there right where cylinder and gearbox surfaces mate.

    I also noticed the shaft bearing has a slight kilter on the inner race when spum around, which must be where that clutch wobble is coming from. Oh well need to be more careful this time.
    #17
  18. PSchrauber

    PSchrauber Long timer

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    Than it is running to fat too and also burning too much oil and/or gas.

    That is too a environment the plugs don't like at all and due fail with a sudden.

    I had the sane oroblem with an old crank seal on the gearbox (primäry gear side) and a carb that did not suite the motor.

    New seals and a proper carb dsolved it and of course simple plugs nothing special as tgese Iridium olugs don't like 2 strokes.
    #18