I mounted mine on the front for a day. It seemed to do okay but I just couldn't get all the stuff juggled right.

I think now I have the ideal solution for me at least.

1. The engine always stays in good contact with the rear wheel.

2. I pedal it down my short drive in full choke.

3. I switch to half choke for half a block after it starts.

4. I turn off the choke and just pedal away.

5. At about four miles an hour it will start.

6. It will shut down automatically when it slows below that speed. (If you have good constant pressure on the wheel.

7. I can start pedaling from a reasonable uphill and have it start no problem much better than even the china girl bike. It is much lighter. Now there is more drag on the rear wheel so it is harder to pedal than the bike would be without the engine but it is doable.

Downside:

You can not just pedal it. the engine will start. I will be carrying a tool kit to take the nuts off the engine hold down to release it. That is just in case of major problem far from home. I'll just tie the engine up and go.

I am still in the test phase but I learned something new today. Even the 25cc which I had no previous experience with has a threaded shaft. It was hidden behind a spacer of some kind. I found the when the spacer unscrewed itself for me by accident. I am now having a new drive wheel welded.

Also I found out that almost all new home improvement store trimmers have the same engine. the two hundred dollar trimmer has a 31cc ryobi engine and so does the 69.99 model.

If you live in a reasonably flat area the 31cc should take you all over the place no sweat. So even if you go new its 75 bucks for the engine another 75 or so for a wallymart bike and a little more for assembly parts, and you have a motorized bike.

I know even here I can get a working 31cc engine at the flea market for 35 bucks and a used bike for 25 bucks. Twenty five more for mounting hardware and for under a hundred bucks you are riding to work instead of walking.

When I am finished with this experimental project, I plan to do a parts list and step by step to convert a weed whacker to bike engine instructions.

If you have hills like me you might take a look at used backpack blower engines. Some of those run 40cc and of course chainsaws

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visit my blog for Riding in the hood,... The home brew bike journal....http://frictiondrivebicycles.blogspot.com/ The deacon's fiction