Mountain Weedy

Discussion in 'Photos & Bicycle Builds' started by daddyfredregill, Sep 26, 2013.

  1. daddyfredregill

    daddyfredregill New Member

    Hi all this is my first build and first post. So here we go. It all started out when I found this old engine from a 1974 weed wacker. The engine is a Tecumseh 85cc 3 hp. It also has a scary looking weed zombie on it which is pretty cool.
    ztuw.jpg
    Sorry the image is upside down.

    So I got the bike all built up with a back rack, chain tensioner and hand made clam shell adapter.
    alxu.jpg

    3ep6.jpg

    guxr.jpg

    I have a 42 tooth gear on the bottom and an 11 tooth gear on the engine. I was so happy and ready to go. But it was not meant to be. I fired it up and i wont move, the engine runs good with the chain disconnected but as soon as a load is put on it it just does not move. If i lift the tire up it will spin it really fast and i lost a chain that way and destroyed it.

    In the early stages of this build I was an idiot and started the engine with the bell housing off the clutch pads. You can imagine what happed clutch pads and springs went flying. I found the pads but the springs were shot. I went to ACE hardware and purchased some music wire, which is spring steel. I bent my own springs and put everything back together. The output shaft does move a little more at idle that it did before the mishap but the bike will still not move.

    I am at a loss. Is it a clutch problem or is the engine really that week? Should I ditch the clutch and just direct drive it, i would have to kill the engine at stop lights then. Or should I get a different engine. I am confused, please help anyone.
     

  2. Looks cool. Id say its your clutch,how does it spin with no chain on it? Might try lifting rear wheel off ground and letting it rip, and see how it moves the wheel with no weight on it,then slowly put it down and see what it does. Pretty sure the clutch is not engaging properly. 3hp would really make it go. Good luck let us know what you find. I googled the motor looking for parts and found a complete engine on ebay,but no clutch parts yet.http://www.ebay.com/itm/Vintage-Wee...d=100011&prg=8141&rk=4&rkt=5&sd=251304218994&



    [​IMG]
     
  3. powerstroke

    powerstroke Member

    Thats a great setup it really is. good job, looks great too.
     
  4. daddyfredregill

    daddyfredregill New Member

    I tested it with the back of the bike in the air. Even at idle it spun the tire a little to fast. Then when you lower it down it just bogs and the engine dies. I made new springs for the clutch out of thicker spring steele wire and it still went to fast at idle. I think the problem is is that this engine is governed at 4000 rpm and the cluth engages at a way to low of a rpm. So it it never has any time to build any hp before it engages the clutch. This was a weed wacker so it probably worked fine for just that purpose. I also ran the engine without the chain connected and it runs fine. I am at a loss. I don't know what I should do. Help
     
  5. Surely you can find some stiffer clutch springs for it. Don't give up on it. Wish I could help more. Might try the http://motorbicycling.com/ website. Maybe someone over there has a clue?
     
  6. zippinaround

    zippinaround Active Member

    do you have a reduction gearbox on it? because if you don't then you have a reduction of 3.8:1 which simply wont work! it needs to be 18.75:1 for the ideal ratio but as close as you can get will do.
     
  7. daddyfredregill

    daddyfredregill New Member

    I am a noob please explain. The engine is directly connected to a centrifugal clutch so I guess No it is not gear reducted. How can I achieve this gear ratio?
     
  8. zippinaround

    zippinaround Active Member

  9. daddyfredregill

    daddyfredregill New Member

    If I can use a pocket bike gearbox. What ratio should I be looking for? I found a 1:5 on ebay, one turn sprocket to five turn engine? With the same gears I have what would my ratio be.
     
    Last edited: Sep 27, 2013
  10. zippinaround

    zippinaround Active Member

    the 5:1 gearbox reverses the drive rotation so you would have to turn your engine around. think you can get 4:1 boxes that don't reverse rotation but not sure if they really are 4:1 cuz i dont have one . you can also get 3:1 boxes so you will have to ask whoever you buy from to check what it is. if its 5:1 you need a 42 would be good. if its 4:1 50 would be good. you can download the ratio calc somewhere on one of these forums
     
  11. LR Jerry

    LR Jerry Well-Known Member

    I would consider a set up like GEBE uses. You could get their belt drive set up. Your title had me confused. I live in Tennessee we've had some mountain weedy growing here.
     
  12. daddyfredregill

    daddyfredregill New Member

    So I am still confused, do newer weed wackers have gear reduction in them? I thought I have seen some smaller cc engines on bikes that just go directly to the tire like my setup. I am so confused.
     
  13. LR Jerry

    LR Jerry Well-Known Member

    Last edited: Sep 28, 2013
  14. daddyfredregill

    daddyfredregill New Member

    So I would not even use my clam shell adapter or the gear I made? I really wanted to use them. What about a pocket pike gearbox? Or a cvt
     
  15. LR Jerry

    LR Jerry Well-Known Member

    This is but one option. The two main questions are: 1) Can you make a drive system connect to your engine? 2) How much money are you willing to spend? The GEBE system probably can be adapted to fit your engine, give you the reduction that's needed and at a minimal expense.
     
  16. daddyfredregill

    daddyfredregill New Member

    Ok I redesigned my setup. I am now using Lorace's rim to rim with a belt method. The only difference is is that I welded my two rims together. So the bike moves now but it is just not very fast. With no load I adjusted the high idle screw and the rpm's were nice and high. Sounds like it is running really strong then I let the tire down and try to go and the engine dies. So I lower the adjustment screw and the bike goes fine it just never gets very high rpm wise. So I don't know what to do. 3 hp should move these s bike very well. Anyone have any ideas.
     

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  17. zippinaround

    zippinaround Active Member

    i reckon your drive pulley is too big! i think lowracer used a 1.5" pulley .
     
  18. daddyfredregill

    daddyfredregill New Member

    I still don't think that would help that much. When I adjusted the high idle screw and made the engine really sing with the wheel in air it is fine. Even if I set the bike down without me sitting on it and try to make it go it dies out. So even the bike by it self will not move.
     
  19. zippinaround

    zippinaround Active Member

    i don't have any experience with weed wackers but i'm sure the clutch would be unusable because it was designed to never have a load on it. you might have to remove it! do a search for whatever make your engine is in the forums and see what others with more experience say.
     
  20. IbedaYank

    IbedaYank Member

    not for this motor its not as it will not rev past 6000rpm if still has governer 3200rpm 10-12-1 is much better on a larger CC and slower turning then the 50cc gx50 that will turn 9500rpm

    it is a 2stroke VERTICAL shaft engine anyway
     
    Last edited: Oct 1, 2013
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