Coral Snake Cobb Job

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After riding a bit over the Summer, the primary drive chain was getting ruined in less time than ever. The last one had about 20 miles on it and was blued in spots, that's getting hot! Going to give up on the Honda and pulled the engine ready to cut off the lower tube and start fresh. The thought ocurred to me that any other project bike or go-cart will need to be belt driven, try and give it one more chance.
Found a three inch alloy pulley in the stash with a 1/2" pilot, drilled it out to 9/16" and then reamed/honed it to the oddball metric size Honda used instead of 5/8", 15.8mm maybe. Filed a keyway and was most of the way there, at least eliminating the feeler gauge shim from the chain drive. Got lucky and managed to get a 5-1/4" pulley to fit on the jackshaft to maintain the necessary speed reduction to my V-plex clutch. Got a belt to just barely fit over the pulleys with some tension. Fairly thin belt, but from what I have read, a thin belt will transfer torque if run at a high speed.
Early results seemed to show promise, with a slight loss of tension as expected from a belt broken in. Got out the rat tail file and made some adjustment slots in the engine mount. Problem solved. Rode it around Greas-a-rama, a local rat rod car show over Labor Day Weekend at the Boulevard Drive-in. Things went well, putting around while Dad ran his motorized wheel chair. Flat ground, no load, no speed to speak of, mongrel cycle did all right. Tried riding up the hill when I got home and could easily tell the belt was slipping. Belt was further down in the grooves than new. A slight misalignment on something so short coupled had worn the fabric off of one side of the belt.
At Greas-a-Rama, I was invited to bring the cobb job to the Mods vs Rockers show at the local City Market "Art of the Machine Series". Sounds fancier than it really was, about half regular scooters and some vintage British motorcycles with the rest just standard fare. Not a single fish-tail parka in the bunch, or anything with too many lights or mirrors. Mine did not fit with either, but got the usual head scratcing and questions of "Why so many belts?" or just "Why?". Would include a link but the filter at work won't let me open "cult or gang activity" hilarious! Nice show, will attend again if they have another. Promoter is somewhat ambitious in his attendence figures IMHO, but that's his right, and job for that matter.
Had to do something to get it to run just a little longer, and too cheap to buy another new belt. Got out a piece of aluminum plate and made this belt tensioner. Worked well enough, perhaps too well. Bearing wore a serious groove in the jackshft from the added side load. Probably not good on the engine bearings either. Hack it off and start fresh.
Wife never did like the looks of the Honda, she thought I should play up the steam punk aspect with polished brass and copper. I'm just not an artist, and that is what it takes to pull that off well. Did give it a rattle can paint job of Rustoleum Dark Bronze. Less coral snake, I like it a little better.
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Well, if we truely learn from our mistakes, I should have several advanced degrees and make more money. Looking around the garage, found not one, but two Lauson engines that just might fit the bill. One an RSC, and the other an RSH series. Can't remember which is which, but I used the bigger bore one off a Toro Roto-Hoe. The smaller was off a Jari sickle bar mower and had gas tank brackets built into the shroud, along with a pleasing shaped opening covered in screen and a cool aluminum starter pulley that looked much better than the plain rusty one off the tiller. So with little problem the pieces were swapped, seemed to have fairly good compression also. Was concerned that the older engine, while heavier may have more vibration so was looking for a less rigid mounting method. I had already moved the final drive front sprocket as far to the rear as possible, limited by the belt rubbing on the bottom bracket. Also installed a shorter crank off a 20" girls Chinese Schwinn. The Lauson mounts with only two bolts inline. I used another bend from the school bus seat and went straight down. The engine bracket was flat steel sheet that I cut out and hammered down. Didn't intend to replicate the rounded shape of the cast engine sump, just worked out that way. Using two pieces of strap steel set vertically, clamped to the rear round tube and let the engine float where it wanted to with the same belt previously driven by the jackshaft.
Engine appears quite a bit lower than the Honda because of the larger flywheel and sump. While walking to the bus stop I noticed the step on a heavy equipment loader made from a large size roller chain. That should take care of the front mount and dampen the vertical vibration, the straps should reduce the horizontal, maybe. Dug thru some rusty tractor parts and found a roller chain that wasn't good for much else, might be a size 50. The added bonus was that no bending would be required for the front down tube.
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Did not take into account the upward thrust of the engine trying to climb the belt, quite a bit of slack develops in that hanger.

With a little coaxing the engine sputtered to life, yeah! Time to add some gasoline and take a ride. With the engine warmed up, there is a spot where it seems to almost lock up. You want to make sure that is when you first start pulling the rope. I didn't and tore off a finger nail and nearly dislocated my pinkie, half way thru the pull. That shiney little crank pulley just doesn't offer any leverage against the mighty 2-1/4hp.

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Got it running fair and it seemed a bit quieter than the Honda, lower tone perhaps. Rode it around and then the hill climb test. Still had to pedal a bit, time to reduce the final drive (again). I wasn't sure a 10 tooth would provide enough chain clearence around the bottom bracket, but I ordered it anyway. A 9 might have fit, maybe, glad I didn't wuss out and go with the 11. Nice thing about going from the 13 to the 10, could take out one whole link and the rear axle is still in a good spot. Added a tensioner on the pedal chain to take up that slack. It was a record high 72 degrees yesterday, so I got off work early and took it for a spin. Does alright, marginal at best. Rusty muffler is blowing out and getting pretty snotty. Don't have the twist throttle hooked up so it is a handfull.
 
I bent another school bus seat tube into an "S" shape to replace the roller chain front tube. Rode it a bit, the reach to the low bars was just too far. Swapped on a set of short ape hangers takeoffs from refurbishing my Mom's trike. Much more comfortable to ride, although it looks more like a chopper than a bobber now. One observer even suggested the handlebars more closely matched the rototiller engine intent.
Installed a throttle lever and better muffler, here it sits. The bent seat tube is not on purpose.
 
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WOW! That is a truly original drive setup that with some tweaking to the variable pulley will get the job done.. I know this is waaay after the fact but I have a Honda 50cc +2 piston sitting in the top of my toolbox.. :)
 

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