Motorized Bicycle Resurrection

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yoothgeye

yoothgeye

I build stuff.
Joined
Jul 1, 2010
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Roanoke Rapids, NC
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Building a motorized bicycle is what brought me to rat rod bikes, but not long after getting here I realized that I wanted to just pedal my 1950 Columbia and put the engine on something else, so this is where we started:

oldmbike.jpg


It was fun, but without a diamond frame I had motor mount issues, I never finished breaking in the engine (cheap eBay kit) but with my GPS in hand on break in fuel I was hitting 36mph. I was happy with that.

Anyway, After removing the motor I had another frame in mind, but until today I hadn't really done any work on it. The motor has been sitting in my shop for about 2 years. Back in the spring I had taken apart a kids OCC Chopper (the 16" one) fork to use on this bike painted it and modified some cups to fit the frame. Today I started some work.

I started by installing the fork, it ended up going on really well. Then I grabbed my wheels. There was a member on here selling new coaster brake wheelsets and I bought a set over a year ago. Alloy rims, heavy gauge spokes, and Shimano coaster. These wheels are beefy. I put on the Bell Streamliner tires, I have these on another bike and I love them. Up top I added a set of bars off of a Kawasaki dirt bike. Years ago I had cut them short and now I wish I hadn't gone so short, but they will work fine.

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I also built a layback seat post. I had actually pulled one off of a monkey bike to use on this bike, but I couldn't find it today. I like this one better anyway, it's made from a piece of weight lifting equipment, so it's strong and I've got a black theme going on the bike (not really on purpose, haha but it's looking good.)

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I quickly ran into my first issue, the 3 piece crank arms hit the motor on the right and the muffler on the left. ugh. I got the left side off, but the right the threads stripped and I eventually got it off. Meanwhile I called a friend who I knew had a parts mountain bike and he brought it to me and I got the crank arms off it it and while I had it I pulled the cartridge bottom bracket and this thing now has good clearance and pedals smooth as butter!

Now facing another issue, I have a 41t "vintage" wheel sprocket for the engine and it fits over the hub but not sure if the smaller bolt pattern will fit around the thick spokes. The 44t that came with the kit (that I didn't use before) will fit the spokes, but the hole in the center won't fit over my hub. Ugh, I'll figure it out. I went ahead and got it riding and I really love the looks. With the fork putting the wheel further forward with a little extra rake (built into the triple tree clamps) this thing tracks really well and will be great when spinning the motor. Enjoy these photos, I wanna be on gas power by next weekend.

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And my daughter just HAD to be in one:
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Looks nice! Are you going to use a front disc?
 
Looking sharp buddy!!
 
Oh yeah, does anyone have a thumb throttle they wanna get rid of? I made mine from a 10 speed shifter off an old Schwinn road bike, it's pretty ghetto. I originally ditched the twist throttle that came with the kit, I didn't even wanna try it, I like thumb throttles, but mine leaves a little to be desired.
 
You can get a good thumb throttle at a powersports store. i agree with your decision to remove the motor kit from your classic cruiser. They are hard to find.
 
wheelbender6 said:
You can get a good thumb throttle at a powersports store. i agree with your decision to remove the motor kit from your classic cruiser. They are hard to find.
Click to expand...

I talked to a friend at church tonight, he works at a motorcycle shop, he initially said he didn't have anything then he remembered his old Waverunner 500 hull, so he's checking that. I just sold my Waverunner 500 in favor of keeping the old WaveJammer 500, but both have the same cool thumb throttle, so maybe that's my answer.
 
OK, the bike fought me a lot, but I got it going tonight.

First the "old" sprocket wouldn't work, so I used the heavy solid one that came with the kit. To do that I had to grind/cut out about 1/16"+ on the inside hole to make it fit over my hub. Once I made it fit I couldn't use the outer rubber piece or the bolt heads would hit my coaster brake arm. So the sprocket is on the spokes, but on the inside I used the rubber donut and metal backing plates, I will be checking this setup often.

The chain went on very well as well as the tensioner. Had I move the wheel towards the motor a little I probably could've run without the tensioner, but then I would've had to do something with chain slop on the pedal drive side.

I wanted to ride so I used my old lawn mower gas tank (as seen in first photo at top) and zip tied it to the frame, put in some fuel and went for a ride. It took about a minute to get it running and I then rode it a few miles, at around 1am in the dark. :shock:

I still am using a heavy oil mixture for break in so it's no "topping out" like a 2 cycle normally does, but I figure once I lean out the oil it'll do better.

Still need a better throttle, mine sticks on the grip at mid throttle, which actually works well as cruise control. I am not use to a brand new quality coaster. This Shimano is strong and I have to be light or it just locks up.

The bike is SUPER stable with the added length and rake from the fork, it ride really well.

For those of you who have used the eBay motor kits, what type of break-in did you do? My motor probably has 10 miles on it now, 2-3 tonight and 7-8 2 years ago.
 
I use "Opti 2" oil at 100:1 from the time i build it and I first gas it up. I have not had any issues. It is a very clean running oil. If you are not that fond of it try regular 2 stroke oil at 24:1 for break in then go up to 32:1. Just my thoughts
 
slowriderz said:
I use "Opti 2" oil at 100:1 from the time i build it and I first gas it up. I have not had any issues. It is a very clean running oil. If you are not that fond of it try regular 2 stroke oil at 24:1 for break in then go up to 32:1. Just my thoughts
Click to expand...

I had to fill it up yesterday, all I had was some Briggs & Stratton 2 cycle oil, I glanced at the motor handbook and it said to run 20:1 after break in, so that's what I did. I'd like to lean out some more, but I want to keep the engine safe.

Are you using just a cheap eBay engine or do you have a nicer one?
 
Well I didnt buy my motors from e-bay but they are the exact same thing. In fact, most of the little chines bike motors are made out of the same couple factories in china no matter who you buy from. I do however put a bunch of extra hours into the motor prior to installation. I also try to get rid of as much factory junk parts as I can. below is one in progress.

IMG-20120106-00201.jpg
 
I have one of the cone type air filters like you have on that bike, is there any difference in it and the stock one with the plastic cover? I haven't tried the cone filter yet.

I have some chain issues right now and working on getting it right, but I'm still riding.

Are you using twist throttles or something different? I made a thumb throttle from an old 10 speed shifter. It's kind of ghetto, but it works, I have a thumb throttle off of a Recon 4 wheeler that I'm thinking of trying.
 
I am using the billet throttle from SBP and the filter came stock on that particular carb. It is a RT carb from Thats Dax and it is the biggest improvement I have ever done ( that and the expansion exhaust :D ). I really do not think the air filter is much of a noticable difference in a stock carby.
 
I never planned to do an "hop ups" to this engine, but I did disassemble the exhaust before I wrapped it and opened up the "crimped" tubes in it with a screwdriver. An expansion chamber would be nice, but to get the full effect you need to make/buy a "boost" bottle for the intake.

Sure I'd like to be able to go faster, but I'm already breaking the law by going faster than I should according to NC unlicensed scooter law.
 
Right as I rode it to church today after swapping on the fattest, cushiest, most vibe resistant saddle I had, an old NOS Hunter cruiser saddle.

mbike1.jpg
 

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