Chinese 4 cycle chain drive problem/ remedy report

Discussion in 'General Questions' started by Will Snow, Sep 1, 2009.

  1. Will Snow

    Will Snow Member

    This is the new kit with the enclosed chain rather than gears. Good kit, BUT, it has problems. I have been told the shaft to the drive sprocket is breaking and becoming a serious problem on several of these kits. After putting mine together and running it down the street, I can see why.

    The Chinese motor is surprisingly good. Starts easy and runs very smooth. Good tork to.

    The encased chain is well done. Good roller bearings and the drive sprocket looks better than the rear sprocket.

    The problem is: When the drive sprock spins it has a bad wobble. after inspection, I found the discrepancy in the way the drive sprocket is attached to the drive shaft.

    After disassembling the drive case I found this: A bushing that had been inserted in the large center threaded hole of the sproclet was welded to the sprocket on the back side. That weld is the problem. The sprocket slides onto the drive shaft and butts up against a ridge in the shaft. the back surface of the sprock should be flat to butt evenly up aganist the drive shaft ridge.

    The weld: It looked like it had been roughly spot welded leaving large blobs of welds. Worse yet, some of the weld was inside the bushing where it slide over the drive shaft. The sprocket that was a very bad fit had been forced on causing the wobble and a off center drive sprock. this bushing has a slot in it to slide over a slotted pin on the drive shaft.

    Well, there you have it. Do you think this flaw would be enough to cause these drive shafts to break?

    I am not a machinest or welder but hope I made clear what I found. I used my dremel to clean up the weld and now the sprocket runs well centered and no wobble.

    Too bad, there are a lot of nice things about this kit but whoever is adapting this for bicycle use is just slaming then tgether with very little or no care at all.

    Boy Go Fast is the dealer I purchased it from and they must by now know there is a problem. I hope this will help someone who has this kit.

    Best Regards

    Will Snow

  2. fetor56

    fetor56 Guest

    Pics Will,if possible.

    TREEWK Member

    i won a livefast rear rack 4 stroke kit on ebay auction for less than $200. it should be here this week. they and boy go fast don`t show much in their adds. thanks for your interesting post. ron
  4. Will Snow

    Will Snow Member


    You are right, pictures make a big difference. I have a couple more improvemets to make, then I'll add pictures with all the changes. Well,at lease I think they will be improvements.??????


    4 cycle under $200, what a deal. I paid more but the price was still fair and the work I had to do was exspected. It is probably the same engine as on this kit and that's good. You may have to do some tinkering but it will probably will work out just fine. Some of these Chinese kits were a little to rough for my liking, but this 4 cycle seems worth seeing through. I also got some good information from people on this forum. If you get stuck somewhere, drop a line. There are some pretty knowledgable member here as you have probably seen.
    I'll watch for your posting, good luck Ron.

    Will Snow