Belt stretching problems with GEBE kit....

Discussion in '4-Stroke Engines' started by fall_down_stand_up, Jul 18, 2011.

  1. I have a GEBE kit with a eho35 Subaru/Robin engine....At 150 miles the belt had stretched so much that the belt tentioner wheel was rubbing up against the drive gear and at 200 miles the belt snapped(I think becouse it got cought up in the gear)....The belt was perfectly alligned and had no wear on it when it snapped....I weight 162 pounds and the hills are not that steep around here....
    Has anyone else experienced this problem????
    I am going to weld a 1/2 inch or so extention on the tentioner arm to make it longer so as the new belt stretches it doesnt end up touching the drive gear....
    John
     

  2. Sadly, my GEBE-Robin EHO35 powered bike was stolen last year. It was head and shoulders the best of the 4 gas motored bikes I have built. I had several thousand miles on the original belt with only a small fraction of an inch of streeeeetch. I'm sorry you are having a problem with yours. I wonder if you got a bad belt?
     
  3. It has to be if you had several thousand miles on yours....I only weigh 162 pounds,so I know it wasent my weight....
    Sorry to hear about your bike getting stolen,thats such a shame....
    John
     
  4. The only problem I ever had with the GEBE kit was when new the tensioner would "jump" back and forth during hard acceleration instead of moving smoothly. Others have experienced the same jumping and have written about several cures. I tried several quick and easy fixes that only worked temporarily. The problem is one poorly engineered design flaw in GEBE's belt tensioner, the tensioner pivots on a threaded bolt. Pivot on threads? That's just Pi** poor engineering. I replaced the threaded bolt with a long bolt I found with a smooth collared section of the correct length near the head without threads. I cut off the unwanted section of the bolt, reversed it, used very thin brass washers on either side of the tensioner, lubricated everything with dry molycoat, and locktighted the standard, thin nut used to hold it on. It is necessary to draw the bolt fairly tight with only very little clearance(slop), but it must not be quite tight either. Perhaps a few thousandths of an inch of clearance is about right. I tried using a nylon inserted locknut, but it's extra thickness interfered with the spring and wouldn't allow the tensioner to stay off the belt when you tried to release the tension using the knob so you can pedal with no resistance. Following this modification the belt and tensioner operated as smooth as silk with zero "jumping". I wrote a thread here covering this mod, but no one seemed to notice it. I think the belt might last longer with less chance of breakage if the tensioner rides smoothly on the back of the belt, thus holding constant tension on the belt, rather than the tensioner binding then pivoting on the threads allowing the belt to be jerked on due to tensioner jump. It was quite difficult to start the bolt into the threaded hole with the spring tension on the bolt, but with patience I managed it. I hope this helps you.
     
    Last edited: Jul 20, 2011
  5. My spring tentioner snapped and am now using a bungie cord that works exellent....It gives just the right amount of tention on the belts....
    I will keep in mind about changing the bolt on the tentioner or atleast lubricating it....
     
  6. strotter

    strotter Member

    I took a piece of old inner tube and made a rubber band. Put it around the tensioner and the upper support. (thus adding tension to keep it engaged) Works like a charm...
     
  7. If you loosen the bolt alittle bit that holds the tentioner arm on it will not hang and it will stay ingaged and you wont need anything but the spring....
    John
     
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