Coral Snake Cobb Job

[nick_ish]

Whoa! Brilliant work love it! ;D

[Mr. Gangrene Genes]

Last Saturday I rode a few miles over to Ralph Wayne's Backyard Nationals. One of the best motorcycle shows you can attend if you are in our town the first Saturday of October. Really more of an "organic happening" with 100's of motorcycles swirling around the neighborhood like a bee hive. The cobb job was not booed or laughed at, really a warm reception for what shape it's still in. Took pictures of a bunch of motorcycles for my Dad who could not attend, forgot to take one of my own entry. Here is a website I found with just a small fraction of what was there. Not sure if the comment is satire or irony, they did feel strong enough that they took a photo of my mechanical novelty.
This Saturday I rode 11 miles over to Steve's Auto in Raytown for their annual Open House. Nice show on the lot behind the shop and they are friends from way back. Swapped the V-plex torque convertor driver for one with more range, the driven seems to be unresponsive to change in load. The 40 year old spring is probably weak. Also have not lower the gear ratio so it slows considerably going up hills. Lovely day for a ride and made it there and back. Knees were complaining somewhat on the ride home, may have to adjust the seat up.
Here is the referenced link, thanks for looking.

http://smg.photobucket.com/albums/v306/ ... 1QQtppZZ16

[Mr. Gangrene Genes]

Finally got a 13 tooth sprocket swapped in for the 16 over the weekend. Rode it about 11 miles to work yesterday in the spitting rain. Gear ratio change made very little difference in the hill climbing ability, however it did slow the descent speed. Many more hills than previous rides, painfully slow. Got passed by a Metro bus, how embarrassing. It is faster than pedaling my mountain bike, 50 minutes compared to 1:20. I surmise that the wider range variable V-Plex pulley was somewhat cruddy when first installed. Now that it is limbered up and properly oiled, the ramp angle is too quick for my application. With any engine speed much above idle, it moves the belt into a higher gear than it can pull. Still very much in the trial and error phase, lots of errors.
Swapped back to the smaller pulley in the photos, replaced the steel pan comfort seat with a springier item off an English racer 3-speed, and the Schwinn approved grips for some smooth black rubber ones. In my quest to make it look more bike like, failed to consider that the finger grooves would rotate with the throttle grip poking the palm. Raised the seat as high as this post will allow to ease the knees, too old to be totally addicted to style. Cobb Job motorbike is really pretty short with the moped tires, seat floats in space now. Not that you can tell with my bulk hovering over it.
Yesterday’s biggest mistake was forgetting the Number 1 rule; in a gun fight, it’s have a gun, on a gas powered device, it’s have some gasoline! Completely forgot to check the fuel level when leaving the house, got to push ½ mile uphill to the 7-11 on the way home. Current tank only holds 87 cents worth, about 15 miles to the cup. Lost a lot of enthusiasm for the project, got some back when it started and made it the rest of the way.
The short chain from the engine to the jackshaft is throwing all the lube off very quickly. Soaked it in gear oil lasterday and it still went dry. Swapped out the high speed bearing that takes most of the load on the jackshaft. Hope it was my poor installation or a defective part because changing that every week or so will get tiresome. Suspect the speed is too fast for the Tractor Supply chain and standard bearing, may have to step up in quality. The rear chain seems to be holding up well. Have not made new rear drop outs, axle has not pulled out of alignment yet.

Won’t be getting much accomplished in the next few weeks. Have plans to build a pedal powered carriage for the Independence Halloween parade.
The main idea is “What if the Child Catcher from Chitty Chitty, Bang Bang teamed up with Prof. Fate from the Great Race and had him build a new collection van?”. Front wheel drive with some cast off 10-speed wheels mounted on swivel bogies in the back. Hello kiddy winkies, I know there are children here, I can smell them. Free Candy & Ice Cream today!
Why do my best ideas involve putting my 5 year old in a cage?

[Mr. Gangrene Genes]

I worked toward the 5-wheeled carriage but didn't make much progress and missed getting to ride in the parade. Oh well, there will be another one next year, start a little sooner for 2012.
Beginning to think the jackshaft chain on the Cobb Job is a fatal design flaw. A 12 tooth sprocket with a 1/2 inch pitch chain seems to me as 6 inches. At the top governed engine speed of 7200 rpm, half would be 3600 feet per minute, or about 40 mph chain speed. Reading some roller chain manufacture specifications, they consider anything over 1500 fpm as "high speed" requiring an oil bath or at least a directed oil spray. Have emailed the gentleman at Max-Torque who recommended this set-up, Jim I think. Have not received a reply if anyone has used the jackshaft scheme for more than a display. Have less than 100 miles on mine and the chain is toast, including the master link. Perhaps a better quality chain will suit, or perhaps a Gilmer tooth cog type belt would work. Emailed Gates about their CarbonCog bicycle belts to see if they would stand up, no reply yet. Don't think I will.
Riding this project as daily transportation seems to be a lost cause at this point. Weather is nice today but can't last much longer. May have to pickle it and try again in the Spring.
Did find a cool fuel tank in the war chest, probably too nice for this project. May still make brackets for it, can always install it on another in the future.

[Mr. Gangrene Genes]

Well I did mount the Briggs fuel tank, also used one of Dad's old aluminum lunch buckets to hold a pair of batteries. The lid has enough clearance to run the wires with out drilling holes or bending anything. One battery for the halogen headlight, one for the taillight I stuffed full of LEDs. Should have wired one to the engine kill to have a running light, with the rest wired to a brake light switch. Live and learn, may change it later. It is somewhat cluttered, not really sold on it. Changed the cable controlled brake to the front, and made sort of a rod activated emergency brake for the rear. Looking around for a lever to use and thought that it would need a bend and a knob. Then I spied a tire iron that meet all the requirements. The pivot and angle is not quite right, takes up a lot of the slack before engaging the brake. Hard steel, difficult to drill, ruined some bits. May have to bend the lower a bit to make it right. Think I am going to give up on the 50cc legal engine for this project, not really working as planned. Probably re-do the lower mount and use a Briggs or Tecumseh. Since this will be mostly used to cruise around tractor shows or fairgrounds it doesn't need to be legal. Plan to use the legal engine for a lighter weight, somewhat more normal bicycle. OK, more of a motorized cycle-truck.

[Mr. Gangrene Genes]

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.

[Glen]

Another ridiculously good steampunk build up...

Boy I love this forum!

Keep it up mate,

Glen.

[deven_science]

This thing is crazy!

[iven]

this kind of insanity defines Ratter' in my book

[Mr. Gangrene Genes]

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.


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.



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.