Bike Bug "Clone" DIY

[Dilly Bar Rob]

So I finally finished my "top secret" DIY friction drive project (my first friction drive, also my first DIY - my other bikes all have HT's and although some fabrication was required on them it was peanuts compared to this...). I've been working on this the past 2 weeks & figured I would share some pictures, you guys will totally love this

Bike is an old Raleigh 5 speed, I haven't looked into what year it may be but I'm guessing 1975-80. Picked it up at the side of the road, was standing among some other bikes with a sign "free" on it. It was in great condition, just needed new tires. It is very light, a pleasure to ride. I figured that I would just ride it "as is" (unmotorized) as I didn't want to try and cram a HT in there for several reasons (chain clearance would be an issue, tubing is fairly thin, and I already have 2 great bikes with a HT on them ). I figured if I would ever do anything with it it would have to be something special, perhaps a custom friction drive, but then I didn't want to do a rear one, it would be a crime to hack up that rear fender + If I needed to ride it in unfavorable weather my back would get dirty....

The motor is a Tanaka TOB120 outboard. 22cc, 1.2 HP. I believe that this is the exact same motor that the Bike Bugs used, the only difference is the carb (which is gravity feed). It was given to me by my friend/boss who jokingly said "slap this on a bike" when he gave it to me. The flywheel cover/shroud was missing (got broken when his dad lent the outbard to someone years ago). Since the coil attaches to it and the part was NLA from tanaka I had to make a mount for the coil from some chunks of steel. I could only guess what the position of the coil relative to the flywheel was supposed to be (ie timing) but since the motor started right after I mounted it I guess I got it right (or close enough should I say). I shortened the shaft that went to the prop as much as I could, cut the prop "wings" off and pounded a sketeboard wheel on there. The 90 degree gear has some slight reduction, not sure exactly what it is, never bothered to investigate. I am sure that it is very similar to the 90 used on the bike bugs. The manual for the tanaka stated a max of 8000 rpm at the prop, if I knew what the engine rpm is at that time is it could be calculated. The engine mount is a piece of 4" channel iron with holes tapped for the engine mounting bolts. The handle to "release" the drive is from a old floor jack that went missing. The swiveling piece on the handle that you turn to make the drive stay disengaged (wedges against the handlebars) is a rocker follower (?) from an unknown engine (found in steel pile). The "rack" that the engine sits on is welded from scrap angle iron and is very sturdy. The gas tank came from the outboard, it is only temporary until I find something better. I am thinking that a copper tank would look awesome on there.


I would write more, but I'm late for work

 

[robin bird]

Very innovative ! it never ceases to amaze me some of the creative talents you guys have. It looks like one of those 1950's British inventions.Is that handel thing coming back towards the driver the accelerator ?

 

[Dilly Bar Rob]

Very innovative ! it never ceases to amaze me some of the creative talents you guys have. It looks like one of those 1950's British inventions.Is that handel thing coming back towards the driver the accelerator ?

Thanks robin Yes, it does look quite "British", doesn't it. the handle (drivers right) is the engage/disengae lever. The engine has no centrifugal clutch, if it did I would have probably had it engaged to the tire permanently for simplicity. I studied how the bike bug engine engage lever worked and couldn't figure it out going just by pictures so I did it this way. The downside is that a LOT of spring tension is needed for the drive roller not to slip (more then I thought was necessary - this is my first friction drive so I didn't really know how much is needed), the upside is zero drag when the motor is disengaged. I have a bolt with a wing top on the left side under the motor, by adjusting this up or down I can control (to some extent) how far the drive roller presses into the tire. The accelerator is the small lever on drivers left, came with the tanaka. There is no kill switch from factory, you simply turn the accelertor past the yellow dot and the engine dies (no set idle screw). The lever has no spring return so you simply set it and forget it, I actually like it, you dont have to constantly hold it with your thumb for cruising. The carb is (interestingly) almost identical to a HT carb, though it seems much better built (duh). The air cleaner IS from a HT (with 2 of the sponges inside for better filtering), the setup on the tanaka had a external filter (missing) with just a plastic "cap" on the carb (was cracked). Since the HT air cleaner bolted right on I may pick up a performance one at SBP, helped the HT's power so should help the tanaka as well.

I just picked up some silicone heater hose & heavy duty clamps so I can attach a small muffler. I really like the look without, but the engine is rather loud at anything but the lowest speed (read that bike bugs were that way too), requiring me to use earplugs. I also started thinking that since the factory pipe was designed to go under water the engine may not be too happy without the backpreasure, dont want to hurt the thing after all the work that went into it.

Total investment in bike now is about $70-$80 tops, all I bought was tires (darned S6 size on the back, took me 2 wrong tires to figure that out, front wheel is from another bike, it uses EA3 sized tires which are much easier to find, a good thing since the friction drive is on that wheel), a gel seat cover, and now the lawnmover muffler, hose (didnt know that silicone heater hose is sold by the INCH) and clamps. My wife is on vacation in europe right now so I gave her the task of finding me a vintage sprung leather seat as these were plentifull there on old bikes. I may go thrift shop hunting for something that I can use for a nice gas tank.

 

[Wheres my dog]

Definately creative there....

Does the exhaust bother you?? Noisewise and polutionwise?

 

[5-7HEAVEN]

Good job on your DIY, Rob.

You can use less spring pressure if you fab an adjustable latch at any point from the pivot towards the lever handle. When you engage the lever, you lock it in at the latch.

A simple Happy Time fuel tank would work.

You can make a killswitch by running a wire to the coil or sparkplug, then to your switch on the handlebar.

I'm working on a BikeBug engine right now. I'm gonna replace that same throttle lever you have with a spring-loaded thumb lever which is included in most rack-mounted engine kits.

I've used silicon hose to reroute the exhaust on the front engine, all the way to the pedals. It worked so well that I did not have to install a muffler at the end of it.

Hope some of this helps you.

 

[Dilly Bar Rob]

Definately creative there....

Does the exhaust bother you?? Noisewise and polutionwise?

Yes the noise bothered me. I attached the lawnmower muffler with the silicone heater hose, it is much better now. Polution wise there is no problem, the exhaust points enough to the side that the smoke goes around me. It doesn't smoke much anyway as I use decent quality oil, and the tanaka only calls for 50:1.

I currently have the 90 degree "transmission" disassembled (it's very easy to take off, just 4 bolts, engine stays on bike),as it proved to be a weak spot. One of my fears was confirmed - the transmission was only meant to take forward thrust generated by the propeller on the boat, it was not made to deal with the side loading I give it by using it for friction drive. It only has one bearing on the back of the housing supporting the propeller shaft, the front of the shaft (which gets the most side loading thanks to my setup) only has a bronze bushing . The units that came on the bike bugs are completely different, they do have two bearings there. After just a few rides I noticed that the shaft had more side play then originally - the bushing was wearing scary fast! Not wanting to ride it till it piled up I disassembled it to see what I can do.....Turns out the solution is easy - just behind the "prop" (now the drive wheel) there is a oil seal - ID=9mm, OD=20mm...well it turns out that they make bearings in that size I have a sealed one ordered (should be here in a week or so), I will simply take the seal out and put the sealed bearing where the seal was. This should be more then enough, the shaft will be then supported by 2 bearings and the original bushing....

Thanks for the tips 5 - 7.

Yes I could run a kill switch that way, the coil even has the terminal for the kill wire. I don't think that I will bother though, I like having just the throttle lever on there - as I say, you just move it past a certain point and the engine is killed, so really no need for a separate switch to do that. I also like the no return throttle. I dont think a HT gas tank would work-it would be too low for gravity feed if it sat on the top tube, I need something on the handlebars.

Before I noticed the transmission issue I took the bike on a longer (maybe 4km) cruise round town. Ran good, very smooth, no vibes at all. I really liked that I could disengage the drive down hill, zero drag and quiet (compared to clutch drag and chain noise of my 2 Happy Times). Also when just pedaling the bike feels no different except the few extra pounds on the front. We have some BIG hills, this was the tanaka's weak spot. No drive slipping, just not enough power (well it is just 22cc....). At the top I was just as tired as the poor lil' engine, boy was I glad the bike has at least the 5 gears, I used every one of them. Still better then sans-engine though

 

[5-7HEAVEN]

On most 2-stroke engines, the tank is lower than the carb, but the engine can still suck the gas into the carb.

Try mounting your tank onto the bike's frame tube. If the engine can still suck fuel, then a Happy Time teardrop tank should work.

Orr, you could mount a goped tank onto the bike frame, that part where the fork sticks thru.

 

[Dilly Bar Rob]

On most 2-stroke engines, the tank is lower than the carb, but the engine can still suck the gas into the carb.

Try mounting your tank onto the bike's frame tube. If the engine can still suck fuel, then a Happy Time teardrop tank should work.

Orr, you could mount a goped tank onto the bike frame, that part where the fork sticks thru.

I thought about that 5-7, but don't you need a special carb so that it draws fuel itself? I am aware that the fuel tank on the bike bugs (for instance) is below the carb, but they have carburetors with a diaphragm chamber (as many 2 strokes do, probably most now days) and not a float bowl like my engine has as far as I know...The carb on the my tanaka is virtually identical to a Happy Time carb. The gas tank on my folder bike is only slightly above the carb, when I go up a steep hill with the tank low on fuel I have flow problems, so the carb definitely isn't drawing any fuel by itself, it is purely gravity feed...

I can't mount any tank in the frame triangle, as I have a special plan for whats going to be in that area. So far top secret, but I will post pictures when it's done.

I am still waiting for the bearing for the transmission to show up, my local bearing supplier didn't have it, and their supplier is waiting for it on their shipment from japan.... I did find bearings of that size on ebay for cheap, but they would probably take even longer to ship and they were described as "electric motor quality" No sense in me saving $5-10
just to get a bearing that wont last very long. Only the best for the tanaka

 

[darwin]

What size wheels are those? 29ers? Scary lookin setup but way cool.

 

[5-7HEAVEN]

Darwin, they look like 700cc wheels/tires.