Proper way to tighten up chain on HT 50cc?

Discussion in 'Frame Mounted Engines' started by ktdfox, May 7, 2009.

  1. ktdfox

    ktdfox New Member

    So, I recently took a trip back to the OC area, picked my MB up, and ordered some parts from dax to repair it, last time I ran it the chain kept slipping off, so I tightened it up as best I could, but on the 2nd ride of any meaningful distance, it broke in my parking lot. What did I do wrong, and how can I avoid it happening again? Pics/youtube links of a demo perhaps?

  2. Mountainman

    Mountainman Active Member

    I have been commenting around here much lately
    regarding these (((((dangerous chains and tensioners)))))

    there are many good words of advice here in the search engine regarding chains and chain tensioners

    recommended -- a good new quality chain and possible better grade tensioner ??

    so that you can ride that THING without breaking down !!
    Last edited: May 8, 2009
  3. ktdfox

    ktdfox New Member

    Dangerous is right! If it had broken on the street instead of in a parking lot, then there could have been much worse consequences for me considering the way people drive...

    There's a couple other issues too that I noticed, like the throttle cable I recieved in the kit simply has to be the wrong one, as you could barely turn the throttle at all with it installed and the idle was high enough that just popping the clutch out and not even trying to pedal you would quickly take off and keep going faster without turning the throttle. That and the shimano crank that is installed has a habit of scraping the left side of the motor :(
  4. azbill

    azbill Active Member

    I have had good luck with using rubber to keep tensioner from moving
    I have also crushed the chainstay from tightening the tensioner before I tried rubber,...just a caution :cool2:
  5. echotraveler

    echotraveler Member

    my chain had problems with the tensioner, it went into the spokes making a pretty bad mess. put some rubber and welded a "slave" now, im not sure how long but seems solid enough......

    the chain...hmmm... try to see if the rear sproket is alligned with the chain, i had that problem too...the chain kept going inward, but after some wheel adjustments i got it to say ......

    to get a nice tight chain you can:

    put the tensioner were it should go

    alling the rear sprocket the best you can that way it doesn't fall off so easy

    then tighten the wheel

    now you loosen the chain tensioner that way you can move it to a less tensioned part, just a bit! remember were it was!

    now rise the white wheel, tighten and then re-position the tensioner to the old position...the chain should be pretty tight now.
  6. ktdfox

    ktdfox New Member

    I was most definitely considering using some rubber to keep it from moving around, perhaps a small section of good old fasioned used tire rubber is in order, though I'd much rather eliminate the tensioner altogether. The arms of the crank are a big concern too, that can't be too good for the engine if they keep knocking it, maybe some thinner ones will help, as the ones on it are fairly thick Shimanos.
  7. echotraveler

    echotraveler Member

    can you take a pic?
  8. fetor56

    fetor56 Guest

    Angle grind the part of the crank that's the sound of it u won't need to grind much.
  9. ktdfox

    ktdfox New Member

  10. Junster

    Junster Member

    Is the motor centered in the frame? Check the mounts. Did the chain jump off to the outside of the rear wheel? It looks from the pics like the motor is shifted to the left. If you can get it to move a lil to the right it may solve both problems. If it is shifting on the frame line the inside of the mounts with some inner tube. Also when the rear spocket is new the chrome makes it a lil thick. The chain sometimes tries to jump a little. You can touch up the tips of the sprocket with a file if it's really bad.
  11. ktdfox

    ktdfox New Member

    The motor was a slight bit (2mm at most) shifted, corrected that and it still scrapes by just a hair. As for the chain, well the old one literally stretched and the master link bent into a "U" shape, but it seems to be taken care of now. All it needs now is the correct throttle cable, the crank ground down a little (can't do it myself) and a dual pull brake lever and it'll be rideable. Spent the past couple days fixing my cage instead, that one's what I use for my 20 mile each way work trip.
  12. HoughMade

    HoughMade Guest

    The master link can only bend into a U shape if the clip and side plate came off. If you use a master link (I do) make sure the clip runs with the closed end forward when the link is on top. The other option is no master link.
    Last edited by a moderator: May 18, 2009