It’s a Hercules K105X from 1972 and needs a LOT of work, but I really couldn’t say no to the offer. This will probably be my main project for 2026.

It’s pretty much complete aside from the missing battery cover and the engine turns over by hand. I had some trouble getting it into neutral, there’s definitely something wrong with the gearbox or the linkage. The tank is completely rusted inside, I’ll probably need a new one.

It might be a long shot, but does anyone in this community have experience with these bikes? The K125 is supposedly pretty similar.

  • RubberElectrons@lemmy.world
    0·
    4 months ago

    Alright bud, congrats, this is how I got into motorcycling as well, albeit on a different make/model.

    Some things to check, if you’re already aware of this stuff my bad, but maybe you’ll find some useful info here:

    1. The tank is probably fine, I used electrolysis+washing soda to derust that fucker over an afternoon. POR15 is great to permanently block water from being a problem again after the initial derust.
    2. Carbs are going to need careful cleaning, I never tried berrymans (gallon of noxious chemicals sitting around is not my vibe), but I do recommend ultrasonic cleaning. The rubber is likely degraded (pinholes, dry rot), see if you can find people making aftermarket replacements which use viton, resistant to ethanol in modern gasoline
    3. For the future, never spin a motor without putting some oil into the spark plugs holes, the piston rings will gouge the fuck outta the piston walls. Gouges = reduced compression, which = lower engine power, besides burning oil. Clean around the spark plugs to prevent any grit from falling in. Pull out the spark plugs, borrow an endoscope camera from AutoZone or whatever, check inside the cylinders for rust or for circumferential gouges left by the rusting piston rings as well. Nobody ever drops a little oil into the pistons before putting them away, the small amount of humidity that sneaks in causes flash rust. You’ll be honing the cylinder wall, it’s a bit of work but not too bad.
    4. Whether you hone or not, best way to check engine condition is using a compression tester, fill the engine with the right kind of oil (should meet at least JASO MA2, no friction modifiers!! They make your clutch permanently slip), plug a charged spare battery in (even a jumper from your car), hook a compression tester to one cylinder while the other cyl has its spark plug thoroughly loosened but not removed (otherwise it may jet oil out into your shop, you can also use some paper towels). Crank, crank, crank, check the tester for the max value. I don’t know this bike, but look for at least 110psi compression, with approx. symmetric values on both cyls.
    5. Save money and use cheap oil during restoration, the filter will catch the important debris as you keep reusing the oil, because you’ll find that as you get closer and closer to proper operating status, you’ll be emptying/refilling the oil to get at internals for inspection/adjustment, thus no need to keep using brand new oil. Definitely use the right stuff on the final fill though, and please recycle the old stuff and the filters at the place you bought the oil.

    Plenty of other work to do, as your life is in your hands, but you’ll learn a lot, and have fun too. Keep an eye out for corroded electrical connections too, there’s a wiring diagram in the manual that’s pretty easy to follow.

    The official service manual is your friend, take the time to read the job first before going for it. Crazy I gotta say that, but I’ve seen other people really fuck some moto jobs up.

    Have fun, keep us posted on your progress!