Mountain Weedy

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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.
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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.
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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.
 
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.
 
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.
 
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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
 
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.
 
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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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.
 
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.
 
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.
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
 
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