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DIY Home Built Motorized Bicycle (non kit) Post all about your home built rides here. Weedwacker motors, lawn mower engines ect. This area is for non kit builds

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  #1  
Old 07-26-2016, 03:37 AM
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Tony01 Tony01 is offline
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Default 212cc 2-speed Schwinn rebuild

Well I blew up my Briggs flathead, took it down a hill with too low a gear ratio and the connecting rod grenaded, even took a bite out of the plastic cam and put a huge crack in the front of the block. This was about 10 days ago. I searched for a briggs 5hp, but my buddy was swapping in a 212 and i wanted to keep up with him so...




Bought a 212cc HF 69727 Predator motor (non hemi dished piston). Removed the governor.. man what a pain in the a$$ to take off that little clip that holds the governor gear. I had to completely rebuild the motor mount and 2-speed. My buddy gave me an 8' length of 4"x4" 1/8" wall box tubing and I got to work with a brand new 5-pack of HF cutoff grinder discs.

Making the engine fit was easy, but there is only about 35 thousandths clearance between the valve cover and the double tubes. If I pound down the lettering on the valve cover I'll have a 3/32" clearance! When the motor isn't supported at the front the vibration causes it to hit the tubes. I added a small tab to support the left predator gas tank mount. My buddy made a Heim joint for his bike that connects the shroud mount up there to the downtube, and cut his gas tank mounts off completely citing a risk of breaking one along with putting a hole in the crankcase. I'll add a Heim joint pretty soon as well.

The 2-speed took me about 40 hours. Hole saw, welder, drill, and angle grinder only. Spacing was difficult. The flange bearings eat up about a 1.25" of shaft space each. The final drive chain is a quarter inch out.. but its a long chain with the frame stretch and the rear sprocket is a 44t kit type that's only an eighth inch thick, so it takes it like a champ with the chain moving around on it. With the pedal chain sprocket limitation there just wasn't a way to get the final chain perfectly aligned. (LIGHTBULB! what if I put the bearing outside the... nah.. it would be too far out.. f*** it...) but it runs, and doesn't jump, and as long as it runs I really don't give a damn about it. The bearing mount bolts on the bottom JS are actually through-studs with nuts on the inside welded to the box tube, so tightening them down doesn't squash the box. Also welded in a little strap on the outside of the box to support it to further prevent bending in case the welds on the stud broke. Had to grind down my bolts for the upper jackshaft and cut relief holes and slots for the 2nd gear clutch and output sprocket.

The frame was wire brushed to bare metal, sanded, and painted with rustoleum truck bed liner. Angle grinder wire wheels are serious stuff. I got bit many times. The finish is very strong, looks good, and is oil and gas resistant.

I made my own flanges from 1" OSH washers (the thick ones!! .190" not the .150" thick ones that come in the same batch!!) and used 1" OD fork parts for both the intake and exhaust. Exhaust was done by cutting pieces with angles and welding them all together for the curves.. it looks like boogers in the corner of the underside of a church pew so I wrapped it up. All I got here is flux core! I also got a welding tan from welding with my shirt off in 90 degree weather.... complete with helmet tan line...

My first gear is 9.3 and my top gear is 6.4. This is approx a 1.45 jump. A 1.45 to 1.5 jump is perfect in my opinion. I have put about 3000 miles on the old 2-speed with a 1.6 jump and while it worked; it was way too much and caused excessive clutch wear, even with throttle blipping on shift. It's much nicer to keep your engine in the power band when it shifts. The top gear of 6.4 is way too damn tall though, but it's all I had for sprockets and I didn't want to gear it too low at 7.7 for fear of over-revving the 212. Tomorrow or another day I'll go down to Grainger and get a smaller output sprocket to get the ratio to a 7:1, will still be pretty tall but better suited I think!

The predator engine is very fat with the shroud and all, so I decided to go with a rope start like I had on the briggs. Anybody considering this should note that you must cut down the plastic fan down to the diameter of the starter cup and use it; otherwise the rope gets stuck in the gap between the cup and the flywheel. I also shortened the cup by taking it just down to the edge of where the slots would be. It really narrows the predator engine down.

The carburetor is a PZ19 slide type Keihin clone. Works real nice and engine idles very smooth! Needs some tuning, have the needed on max fuel setting for the midrange (lowest clip position). Still have some small things to figure out, like getting matching bolts here and there, putting the license plate back on, etc.

I just rode my first 15 miles for break-in motoman style and MAN does this thing haul. Was passing cars that were doing 45-50.

I'm surprised nothing broke or fell off on my first 212 adventure. Guess I finally figured out how to build 4-strokes...
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MxTrq clutch tuning | msrfan 2spd | 212cc 2spd | 3.5hp 2spd | Thud 2spd | CVT tuning
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  #2  
Old 07-26-2016, 09:34 AM
msrfan msrfan is offline
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Default Re: 212cc 2-speed Schwinn rebuild

Nice job Tony. Looks bullet proof. I love that Powerglide effect when it shifts under power.
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  #3  
Old 07-26-2016, 06:22 PM
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Tony01 Tony01 is offline
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Default Re: 212cc 2-speed Schwinn rebuild

Thanks Dale! Starting it cold
https://m.youtube.com/watch?v=AuH3iNGh5DY

Yep the shift is nice. It wears the clutch faster though. When I feel it complaining a bit right before the shift I blip the throttle to take the load off and let the clutch lockup without slipping too much. Depending on throttle input you can have an early or late shift too.
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I don't always listen to Alice in Chains..... but when I do, SO DO THE NEIGHBORS
MxTrq clutch tuning | msrfan 2spd | 212cc 2spd | 3.5hp 2spd | Thud 2spd | CVT tuning
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  #4  
Old 11-04-2016, 07:41 PM
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scratchbuilder scratchbuilder is offline
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Default Re: 212cc 2-speed Schwinn rebuild

Your frame is what id like to build. I like the low..2feet on the ground when you stop. Gotta go have a look at a 212. See if it looks too big for me to say..."naw Sir, its only a 4hp, officer��. I'm thinking a mm like Gilbert did. Like the acoholic says.."I can stop building anytime"��
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  #5  
Old 12-18-2016, 02:13 AM
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Tony01 Tony01 is offline
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Default Re: 212cc 2-speed Schwinn rebuild

This build is always under construction. Since the rebuild in July, I've done a number of things:

Made a new exhaust header. tubing is 1" ID, flange is 3/8" thick, and the brace tab is 3/16" thick. The inside of the pipe was ground and sanded smooth to 320 before welding each successive piece. ~9hrs

thumb_IMG_2505_1024 by Tony K, on Flickr

I didn't wanna wrap it, I thought it was so pretty

thumb_IMG_2509_1024 by Tony K, on Flickr


Also fixed my intake manifold and adapted it for the stock predator carburetor, because it was bending too much and causing air leaks. Increased thickness from .120" to 5/16". Port matched to engine!

thumb_IMG_2541_1024 by Tony K, on Flickr

intake flange by Tony K, on Flickr

thumb_IMG_2416_1024 by Tony K, on Flickr
__________________
I don't always listen to Alice in Chains..... but when I do, SO DO THE NEIGHBORS
MxTrq clutch tuning | msrfan 2spd | 212cc 2spd | 3.5hp 2spd | Thud 2spd | CVT tuning
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  #6  
Old 12-18-2016, 02:26 AM
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Tony01 Tony01 is offline
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Default Re: 212cc 2-speed Schwinn rebuild

Modified the carburetor to have an adjustable main jet. Did this by drilling out the stock jet to approx .055", and modifying a Tecumseh adjustable jet so that the adjusting needle screws all the way down to bottom out on the jet, and not on the bowl nut. This involves drilling inside, re-tapping a few threads, turning back the bowl nut head (I chucked it in a drill, turned it on, and used an angle grinder to turn it down, but a lathe is best of course).

Works great!

212 adjustable jet mod by Tony K, on Flickr

mod vs stock TEC adj jet bowl nut by Tony K, on Flickr

clamping fixture and bigger hole in stock 212 jet by Tony K, on Flickr


This is where the needle normally bottoms out. The stock bowl nut must be shortened down to approx .040" away from the smaller diameter, then the small bore must be drilled out and tapped a few threads same as the other ones, because the end of it must be bored down to allow the needle to screw further into the bowl nut. Best done on a lathe but I did it with hand tools.
bowl nut cross section by Tony K, on Flickr

completed adj jet mod by Tony K, on Flickr
__________________
I don't always listen to Alice in Chains..... but when I do, SO DO THE NEIGHBORS
MxTrq clutch tuning | msrfan 2spd | 212cc 2spd | 3.5hp 2spd | Thud 2spd | CVT tuning
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  #7  
Old 12-18-2016, 02:40 AM
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Tony01 Tony01 is offline
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Default Re: 212cc 2-speed Schwinn rebuild

Braced the rear end with 1" C-channel for the chain stays, 3/4" box tube cut lengthwise for the seat stays, and 1/8" steel for gussets.

Put new tires. CST Cyclops 26x2.4. I only have 500mi on them so far but I really like them.

seat stays separated as i was bending the box tube in, so I welded the entire area up.

weak area by Tony K, on Flickr

Just bent the c-channel over my knee while fitting and grinding.

1" C-channel chain stays by Tony K, on Flickr

nice flux core welds by Tony K, on Flickr

painting rear end by Tony K, on Flickr

made a tab for the brake reaction arm that bolts onto the gusset.
rear gusset by Tony K, on Flickr
__________________
I don't always listen to Alice in Chains..... but when I do, SO DO THE NEIGHBORS
MxTrq clutch tuning | msrfan 2spd | 212cc 2spd | 3.5hp 2spd | Thud 2spd | CVT tuning
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  #8  
Old 12-18-2016, 03:14 AM
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Tony01 Tony01 is offline
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Default Re: 212cc 2-speed Schwinn rebuild

Setup a brake light using a magnetic switch. It's tricky to mount on a lightweight hydraulic MTB brake lever, but I figured it out. The magnets are epoxied to the lever, and wrapped with some window screen also epoxied in for strength. A 450ohm resistor was the best one for me.

Everything is wired with frame as ground. Only one wire goes to the taillight. The on/off switch turns on the headlight, and the taillight in series with a 450ohm resistor and a diode. The brake light switch is wired to +12V and the taillight switch, so it works for day (off pos) riding. The diode in series with the resistor is what prevents the headlight turning on during the day when I hit the brake.

magnetic brake light switch by Tony K, on Flickr

Unfortunately my dash is not lit.

dashboard by Tony K, on Flickr

headlight is awesome!

autozone $30 round light by Tony K, on Flickr

This build is my daily driver and I need to be able to ride it in any California weather. This usually means heavy winter rains. I've ridden without fenders and it's only 5 minutes before you're soaking wet on all sides. Fenders are a must. I ride in the pouring rain all the time now if I feel like it.

I used bairdco's instructions on how to mount fenders from his thread (thank you sir!) Used the same heat shrink tubing. Had to make my own fork mounts as I have a QR axle on the front. Made fender tabs, fork mounts, and annealed them with propane so they hopefully won't crack. The fork center mount tab attaches to the steerer on both sides, and the fenders are rubber mounted on every point. So far so good. Love riding in the rain now, just gotta figure out how to stop my visor fogging up.

Also installed this glass pack straight-through muffler I got from a motorcycle dirt track machine shop I applied at. This muffler is really, really BAD A$$. Super quiet but when you open it up man does the engine sound off! Way better than an open header. I'm now a glass pack man. Welded a section of the c-channel at an angle to the seat stay to provide a mount for the muffler with a section of 1/4" rubber.

glasspack mount by Tony K, on Flickr

The bike is an absolute joy to ride now. I feel much safer having a brake light and better about going out in uncertain weather. It looks better, too. I routed all the wires together. The brake light wire runs with the drum brake cable and the tach and kill switch run with the throttle cable.

with glasspack by Tony K, on Flickr
__________________
I don't always listen to Alice in Chains..... but when I do, SO DO THE NEIGHBORS
MxTrq clutch tuning | msrfan 2spd | 212cc 2spd | 3.5hp 2spd | Thud 2spd | CVT tuning
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  #9  
Old 12-18-2016, 03:31 AM
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Tony01 Tony01 is offline
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Default Re: 212cc 2-speed Schwinn rebuild

But, there's trouble. My 2-speed top gear chain has eaten up my sprockets. I think I know why people use #35 chain. because the sprockets are bigger for the same diameter making the chain flex less per link. In the meantime I've swapped the bike to single speed with a single jackshaft. Although I really miss and prefer my 2-speed, I do love the simplicity of a single that I've not felt in a long time. The gearing is 7:1 and the clutch is starting to get worn out, running a black spring with mixed heavy/regular shoes. I'm probably going to swap to either all heavy/black, or all regular/green.

My 2-speed clutch looks real bad on the sprocket and the bell is worn deep after thousands of miles of shifts, but the bronze bushing still looks good. I guess the oiling every hour was too much maybe, but who knows. Most of my shifts were easy. I would blip the throttle when the clutch would start chattering. I figured it would save it somewhat. Guess it did on the bell. I could probably use the bell for another couple thousand miles, although it is really worn a lot along with the shoes.

tired sprocket by Tony K, on Flickr

2nd gear clutch 4000mi by Tony K, on Flickr

keyway of death by Tony K, on Flickr

The next bike modification is to drop the engine down over the bolts that hold the aluminum seat tube clamps together. I ordered and received some flathead allen bolts, 3/8" 3" long, and what do you know, I don't even have a countersink big enough to make them work. I plan to countersink the engine mount plate and then slide the engine right over em. I should gain an inch of valve cover clearance so that i can adjust the valves with the engine in the bike.

engine clearance by Tony K, on Flickr

I'll also completely remove the gas tank mounts (I've been using the drive side one) and will make a mount on the down-tube using an old 1" gooseneck.

right side by Tony K, on Flickr

see my other thread for the trailer I'm building!
__________________
I don't always listen to Alice in Chains..... but when I do, SO DO THE NEIGHBORS
MxTrq clutch tuning | msrfan 2spd | 212cc 2spd | 3.5hp 2spd | Thud 2spd | CVT tuning
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  #10  
Old 12-18-2016, 05:58 AM
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Ludwig II Ludwig II is offline
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Default Re: 212cc 2-speed Schwinn rebuild

You do realise you've created a motorcycle with the same style as some early 1950s Japanese types?



1952 98cc Minato Health





Tohatsu TFL-80




Last edited by Ludwig II; 12-21-2016 at 09:09 AM.
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