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Thread: rat bike pictures 1936 Hawthorne
01-07-2007 #1psuggmog Guest
rat bike pictures 1936 Hawthorne
As promised here are some pictures of my previously mentioned rat bike.It is torn apart right now since I am working on modifications. The copper tubing in the first picture is part of a new tank mockup.
It is a 1936 Hawthorne frame, 1950s Monark springer fork, 1930s schwinn brakes: front drum, rear cantilever, 9 speed rear hub: Sturmey archer AW threespeed hub with a cyclo triple hub sprocket shifted by an mid 1960s chrome plated bronze Campagnolo Record derailleur. I modified handlebars from a small dirtbike by brazing a Campagnolo braze-on downtube shifter, and brazing on cable guides made from the inner rollers from bicycle chain. The 1950s era three speed hub is shifted by a 1930s vintage top tube shifter mounted on the handlebar.
The front hub is a 1930s Schwinn drum brake. I originally built this bike as a mountain bike prototype in 1980. All the parts except the front fork, rear hub and derailleur, alloy rims and tires, and handlebars were made before WWII. I built the wheels at this time with the only 26X1 1/2" rims alloy rims available: Araya. I made a headbadge from an emblem off of some old machine , thus conceiving a bike brand that never was.
I rolled it to fit the radius of the headtube. I used a Monark springer fork off of a girls bike because of it's longer steering tube. I put large washers between the forkcrown and the crownrace to lift the headtube and give more bottombracket clearance since this was an off road prototype. The frame is from a Hawthorne brand bike which was sold by Montgomery Ward. It was made by Cleveland Welding Co who made many brands for numerous companies. When I first got a chinese motor, I was planning to put it on either an old Schwinn straight tube or a phantom frame, both of which I had lying around. Both these frames had curved downtubes and I didn't like the way the motor fit the either frame. The rat bike has straight down and seat tubes and they were at the exactly correct angles to fit my motor without modification. I don't like the way the teardrop tank fits this frame, so I am in the process of making a tank to fit between the toptubes. I also didn't like having two left handlebar levers(1 clutch, 1 brake). I didn't want to use a twistgrip type clutch control either. I ended up taking a barend gearshift lever and modifiing it to use as a clutch lever. It has more travel than the stock lever and is adjustable for tension. I have it rigged to run in the down position(out of my way) and disengage the clutch in the up position. This is still out of my way but increases the width of the handlebar by 1.5 inches. On most motorcycles the left lever is the clutch and the right lever is the front brake. On most bicycles the left lever is the front brake and the right lever the rear. I decided to go with the standard bike lever setup, since this is more bike than BIKE. I have a few more pictures which I will post right after this.
01-07-2007 #2psuggmog Guest
I have been thinking about other carbs that would work with this motor. the middle one came off a british seagull outboard. It fits right on the stock intake manifold, the floatbowl hangs down into the clutch lever travel path. I changed The carb on the right is fron a 50cc 2stroke honda spree motor.
The tank on the right is the fake tank that was originally on the ratbike frame. I am working on buiding a gas tight tank this shape to use on the ratbike. i am planning a little protected compartment at the rear of the tank covers to hold the CDI unit. The sparkplug lead is long enough. and this would hopefully provide a little moisture protection and visual relief from looking at that modern thing on an old collection of rolling parts. I'm also working a new longer exhaust pipe, possibly with an expansion chamber.
Here is a comparision picture ofan old homelite 2stroke motor and a 48cc Grubee roundhead. I'd like to try modifing old motors like this to bike service.
01-07-2007 #3Mile High Chop-Ped Guest
Looks like you have a lot of fun stuff to work with. I don't know about the bar end for a clutch. It takes quit a bit of pull and you use it a lot. I have found it is not to much trouble to run the clutch with a couple of fingers and then brake with one of two of the others once you get the spacing right. Of coarse if you can get the bar end to work and lock in and out it might be pretty trick.
01-08-2007 #4Minnesota Hyena Guest
wow those things are like antique that still runs
01-08-2007 #5gone_fishin Guest
i've been taking my time about enjoying all your pics, psuggmog. you get to mess around with some pretty cool schtuff
i could say i'm speechless, but i'd be lying...i know exactly what to say:
"mom! hey, MOM! ...can i ride my bicycle over to psugg's and play?"
01-08-2007 #6Wheels Guest
psuggmog, you mention an old seagull motor, I know that these are legendary reliable micro outboards, any further application beyond the carb?
01-11-2007 #7psuggmog Guest
The carb pictured is from a british seagull model forty minus. It has a 64cc engine rated at 1 1/2 hp. The motors were built for heavy use in salt water. They use a 10:1 gas to oil mix. The cylinder is cast iron and water cooled. The engine crankcase isn't much wider than a chinese bike engine but the flywheel sticks out several inches. Many of the seagulls have an oval cross section 2.2 liter brass fuel tank which would work well on a bicycle. The throttle lever in well made and reminds me of the choke control found on old limey thumper motorcycles. It could be used on a bike as well. I have thought about machining off the waterjacket and casting cooling fins around the remaining part, shortening the driveshaft, using the bevelgear finaldrive minus the propeller, to make a shftdrive bicycle engine.
01-11-2007 #8Wheels Guest
Yeah that tank sure looks better than the coleman stove tank, I think if I had a motor like that I would be building a boat.
01-11-2007 #9psuggmog Guest
I was given this motor because it has a piece broken out of the crankcase where the tiller handle had attached. The break is across a gasket surface. I might try tig welding the piece back in, but the crankcase has to be vacuum tight. Thus, I've been considering using some of the parts in bike motor applications.
01-11-2007 #10Wheels Guest
I understand replacement parts are readily available for type of motor, could you not replace the crankcase?