2 speedTomos moped engine on bicycle frame

mdlee1957 & 37Elgin,
I can see that in frame these moped engines take some fitting and are not plug and play. Mounting them is the challenge, isn't it? But I can also see that the results are pretty impressive. 66 mph on two wheels is more than I will chance fate. Wow. I feel like I'm really clipping along at 35.
I'm curious on the Elgin what sprocket count you used on the rear wheel. And is that a larger sprocket coming off the engine? With that Tomos A35 did you alter the pedal on it so that now it is strictly a kick start? If so, that's pretty cool. When I should have been sleeping last night I was thinking about that old Elgin and picturing a straightbar Schwinn panther frame with a nice inframe gas tank and the Tomos engine... that would make an impressive machine with plenty of power to handle a canoe sidecar and all on a budget.
I have a feeling that now and then we're going to see more moped engines powering bicycles, thanks to the pioneering work of you guys.
If either of you have photos showing your work in progress I hope you'll share them.
SB

I was kind of hoping you had made the modification to kick start. No doubt it can be done. Did you have any issues with the pedal crank running into the engine? How did you mount the driven sprocket on the rear wheel? It looks like a coaster brake hub, not skip tooth but more recent. Nice.
SB

1937Elgin,
I've been staring at your engine mount setup, trying to understand what you did.
Did you utilize the hanger from the moped frame?
Did you weld the hanger above to the bottom of the crossbar and behind to the seat tube?
What metal did you use to cover it all and so nicely wrap around the seat tube?
Is the metal shrouding under the engine mostly for cosmetics?

I don't suppose you have any photos of your work mid way?

In thinking about your build, it seems to me that it is just about perfect in my book... vintage cruiser frame, in frame gas tank, engine fills up the space and looks like it belongs there, plenty of power while technically being legal (at 49cc anyway), 2 speed automatic transmission for the best of both worlds... low end grunt with hill climbing and top end speed for cruising without winding out the engine. It has about everything I want in a bike and best of all by scrounging used moped parts it yields about everything you need to finish out an old frame, other than having to build the wheels to incorporate the moped hubs. It is a high quality, high performance, budget minded build. I think we're going to see more builds being done along this line. At least one more anyway...
SB

Thank you for those photos... they say it all. Perfect. I had been wondering about the curve in the seat tube of your bike and now it makes sense. The pictures are also helpful in that I could show them to a welder and he would understand right away what needed to be done. I have an Indian friend back home who is a welder and loves to make things... rides around in a WWII army jeep with a fifty caliber machine gun mounted which he made. Also made the cannon in his front yard. He's a little different and I think this might ring his bells nicely. Ha! Is that a Worksman frame?
I always liked the 49 to 51 Fords. Nice work on yours! I used to have a 41 pickup and a 41 sedan delivery which was a joy. Old Fords rule.
Thanks for posting the photos... they give me a lot to think about.
SB

While the engine mounts are the same on the Puch and Tomos engines, I see that the overall shape is different, with the Tomos head rising at a slight angle. Do you think the Tomos engine would fit equally well in the Worksman frame? For this application, I like the shape of the Tomos engine a little better as it follows the lines of the frame better and also looks like it could sit a bit lower in the frame.
What is driving my questions is the Worksman you see pictured at the upper left as my avatar. I built it last summer and overall am pleased with it. However, I have been wanting gears for hill climbing and did some figuring with the cost of a jackshaft kit and internally geared rear hub to go with it... not cheap. So, I'm thinking about a partial rebuild of that bike and using the PK-80 on a different build. I would have the frame modified, repaint, change the in frame gas tank and end up with an awesome bike. The main expense would be in paying a welder to alter the frame... probably a good bit less than the cost of a jackshaft kit and internally geared rear hub. But it isn't just the cost savings. It is ending up with what I wanted in the first place... a capable cruiser with hill climbing abilities, low end grunt, and impressive top end speed... all in a bike that turns heads. This would do it. Now I need to see if the pedal start can be converted to kick start. I'm hoping it is just a matter of switching a few stock parts... that's my guess.
Another question. My A35 has an oiler setup where there was a little reservoir under the seat which had an oil line running to the carburetor, so that the two stroke oil mix happens there with a little internal pump. I did some reading on the Moped Army site and see that some people disconnect this and mix the gas manually. Which route did you take? What would you advise? I've been so happy with running opti-2 in my China girl engines that I'm tempted to use it again, but the mix would be all wrong with an automatic oiler which is set up for a 50-1 mix. I suppose there's a good smokeless 2 stroke oil at 50-1. Anyway, I'd appreciate your thoughts on this.
Pictured below is my "Indian" that would get the Tomos A35. Sidecar was made from a Grumman canoe.
SB

Forgot to attach the picture. Think the A35 would fit?
SB

Forum member Curtis Fox is making me a leaf spring front fork for that bike. I'm excited to think that with frame modification the A35 could power that bike and the sidecar. With a heavier frame for the sidecar and stronger mounts to the bike I think it could haul an adult in the side car and still handle hills. Fasteddy is going to advise me on the sidecar frame modifications next summer. This bike would be my ultimate dream build. While it is all apart I have some minor things to change and improve. A copper gas tank will replace the cylindrical one, change the mounting for the rear rack, little things.
I've told this before, but will repeat the little story... as a boy my big brother said that someday he would have an Indian motorcycle with a sidecar and that I could ride in the sidecar. We grew up and he forgot about it. I didn't forget and never grew up. So this is my "Indian motorcycle".
I guess you can tell I'm enthused about your build and the possibilities it opens up for me and others here. Pretty cool. Thanks,
SB

Yes, I'm figuring in the bigger bore kit & don't know that I would actually be riding around with a passenger and if so, then likely a child and not at speed. And yes, I might also change the gearing for more grunt and less top end if need be.

RebelHellbilly said:

tomos iz 1 of best mopeds. i have had a few. wut ya paid for that 1 iz good deal if the motor N all iz good. it looked straight from wut the pics show and its got that turbo pipe! i had that would do 45 plus. would be interesting onna bicycle frame tho

Click to expand...

What CC was that engine that would do 45? I don't know whether this engine has the big bore kit or is stock other than the pipe. The big bore kit seems pretty reasonable. Might need rebuilding anyway, but it sounded good when I fired it up and started easily. Carb is off though, as the throttle was not right. I can worry about that later.
I like that it has enough juice from the magneto to power headlight, tail light, brake light and turn signals... horn. I'm glad I got that engine and think it is going to work out. Do you know if the peddle start can be converted to just a kick start?
SB

RebelHellbilly said:

tomos iz 1 of best mopeds. i have had a few. wut ya paid for that 1 iz good deal if the motor N all iz good. it looked straight from wut the pics show and its got that turbo pipe! i had that would do 45 plus. would be interesting onna bicycle frame tho

Click to expand...

What CC was that engine that would do 45? I don't know whether this engine has the big bore kit or is stock other than the pipe. The big bore kit seems pretty reasonable. Might need rebuilding anyway, but it sounded good when I fired it up and started easily. Carb is off though, as the throttle was not right. I can worry about that later.
I like that it has enough juice from the magneto to power headlight, tail light, brake light and turn signals... horn. I'm glad I got that engine and think it is going to work out. Do you know if the peddle start can be converted to just a kick start?
SB

Regarding a pedal to kickstart conversion, I asked on the Moped Army website and there were several suggestions. One would be to swap out the whole lower part of the transmission... which would be the neatest way to do it. Second is to just remove the right side pedal and use the left pedal as the kick start. That would be the simplest, but would leave the pedal sticking out and no doubt it would get in the way of my leg. Third would be to get just the kick start arm and switch it with the left pedal. That's not bad, but something would need to be figured out with a spring return. Fourth would be to make an arm which could fold in against the engine and spring back. At least it can be done. This build is not going to happen overnight, so I may be able to find someone who wants the whole pedal start to make their moped legal and do a swap. That's what I'll shoot for.
SB

mdlee1958 said:

Orrrrrr, just one pedal arm and a folding pedal.

Click to expand...

That's a thought... along with a return spring.
SB