Soon-to-be-steam engine arrived today. The 49cc motor I ordered came with a "68.5cc" tag on the side. Hmmm. Oh well.
Had a ton of fun ripping this thing apart and busting off the cooling fins. Steam engines like to run hot, just the opposite of IC engines. Back in the day, some even had preheat jackets around them where steam passed through before entering the cylinder. If the cylinder is too cold the steam loses it's power almost instantly as it condenses.
The piston had to come out because I'm adding a valve tappet on top of it to actuate a reed valve in what will be a modified head.
Tomorrow I'll take an angle grinder and dremel tool to the block and remove all the unnecessary castings. I won't need the clutch or cross shaft or magneto. It will have a fairly heavy pulley on the left side (steam engines like some mass on the crank) and that will drive a belt to a Whizzer-type pulley on the wheel. That's it - no jackshaft or anything, just a two pulley system. "The clutch" will be a lever with a roller at the lower end that tensions the belt. Real old school.
QUESTION: What size pulley should I put on the motor to mimic the stock gearing? Of course, I'm assuming the stock gearing (generic bike kit) is correct for this bike, but that's a total guess. The rear pulley is 14.5" (inside the groove).
Here's the victim:
Here's after I had some fun: