2nd build, in progress 1955 AMF Roadmaster, 99cc preddy, cvt

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beltbuckle

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Aug 22, 2011
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Keep checking off tasks on my second build.

bike started off as a 1955 AMF Roadmaster, frame was in good shape, wheels had seen better days.


roadmaster2



Got her stripped down to the bare frame


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Ordered 2 x 26" husky wheels with 11g spokes, and sturmey archer drum hub on the front. Put Maxxis Hookworm tires on the new wheels only to find the back tire wouldn't clear the chainstays. Elongated the rear dropouts a bit to fix that.


chainstay_mod


Hookworms on! Installed sportscarpat's rear sprocket adapter, layback seat post, and new saddle


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Got a Monark II springer for the front, starting to look like a bike again.


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beltbuckle

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Aug 22, 2011
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Found a tank from what I think was from a 1971 Yamaha dirt bike. Picked up an old ZOOM adjustable headset for $5 to get the bars a little more forward and have better clamping pressure than the old forged stem. Welded the front tank mount to the top tube tonight. I really think this tank flows well from the frame up the the stem.


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next steps:

Have sportscarpat's crank set that I'll be putting on, but the outer bearing race was about 0.040" to big to fit in the bottom bracket... took it to a machine shop last friday to have them lathe it down to fit. After that can start working on the motor mounts.
 
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Don P

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Sep 1, 2010
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Hi nice bike. big tank looks ok but this style of bike need a inframe tank. imho good luck with your build it will look good with the yamaha tank too.
 
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beltbuckle

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Aug 22, 2011
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Thanks Don. Yeah an in-frame tank was my first thought as well but honestly fabricating a tank is probably beyond my skillset and time budget at the moment and I'm happy with how this one looks. Can always change it later but for now I'm happy with it.
 
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beltbuckle

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Aug 22, 2011
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Well finally made some progress and got the engine mounted. Bike is now rideable and rides well. It sure is fun to ride. I'm going to put a 100 miles or so on it to work the bugs out, then take it apart and paint the frame.


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Love the takeoff on the torque converter! Will be great for city, stop and go traffic.
 
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beltbuckle

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Aug 22, 2011
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CroMagnum said:
Actually I believe it's from a 1972 Yamaha LT2 100 Enduro.
Click to expand...

Good eye! I bought the tank from a salvage yard and just kind of scoured images on the internet to see where it may have came from. Thanks for the info! Hard part was finding the fuel valve petcock. Finally found one on ebay overseas and had it shipped here which pretty much halted progress until it came.
 
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beltbuckle

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Aug 22, 2011
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Meridian, ID
JonnyR said:
lookin good how hard was it to make a kit for the predator?
how many hp is it ?
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I think it's rated at 3.5HP. No kit here, just hours in the garage and beer.

The hardest part was mating the engine driveshaft to the torque converter since the torque converter was built for a 3/4" shaft and the engine has a 5/8" shaft. See the thread here for how I dealt with that: http://motorbicycling.com/showthread.php?t=40015
 
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beltbuckle

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Aug 22, 2011
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JonnyR said:
cool where did you get the CVT form and what kind of ratio change does it provide
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The CVT is a chinese clone of the Comet TAV2, they are readily available on ebay for about $100. You can pick a 6" or 7" driven. I have the 7" driven. I forget the ratios but you can research them here.
 
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CroMagnum

CroMagnum

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Sep 2, 2011
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beltbuckle said:
Good eye! I bought the tank from a salvage yard and just kind of scoured images on the internet to see where it may have came from. Thanks for the info! Hard part was finding the fuel valve petcock. Finally found one on ebay overseas and had it shipped here which pretty much halted progress until it came.
Click to expand...

Dude! Next time ask! Yamaha used the same two petcocks on all their steel tanked enduros from the "1" series in the 1960s (DT1, CT1, RT1, AT1. etc.) and the second series through the late 1970s (LT2, DT2, DT250, RT360, etc.) Either mounted 2 screws from the bottom or a screw-on collar. They're available all over eBay.


http://www.ebay.com/itm/270664947687



There's an advantage to being real old and cranky because sometimes you actually remember junk like this. :D
 
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NEAT TIMES

NEAT TIMES

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May 28, 2008
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beltbuckle

Very nice and dependable build ! Am doing a 140cc in a Chrome Stretch Cruiser. Already have everything for manual belt clutch, but thinging of the cvt system again. Have the 5/8 motor shaft problem. Where did you get the bushings?

I bid on several of the Bullit Line CVT`s, they all went for well over $100.

Thanksfor sharing.

Ron
 
NEAT TIMES

NEAT TIMES

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WZ

Thanks buddy. Did order the cvt system today = $134.99 w/free s&h plus a donation for our Fallen Heroe`s.

Do have 2 streamlined pillow brgs and 5/8 shaft ectera. May eliminate the CVT plate, want the motor centered in the frame. That may make easier aligning of the rear chain.

Also may let the cvt clutch slide in closer to the motor.

Have ac in my 12` x 20` insulated work area. Have been threatning to build this "motorized bicycle" for 3 yrs! It has a "gooder" chance now!! lol

Ron PS; ordered the last 2 bushing`s. Thinking, maybe cut the bushing slot wide enough to kill 2 keys with 1 slot!!! Huh Mister?
 
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beltbuckle

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Aug 22, 2011
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Well I put about 10 miles on the bike today, gradually going further and further from home. No issues have cropped up yet which is good.

Off the line acceleration is realy good, way better than my other bike with a cent. clutch. Top speed is about 32 MPH, verified with a GPS. Don't have a tachometer hooked up yet but the RPMs at full throttle cruise are not very high, sounds like less than 3500. I wanted to have a top end of about 30 since that is what the law allows so I am happy. It really just loafs along in the high 20's which is perfect for my mission of zipping around to work and around town.

Was going to put a hot dog muffler on the end of the pipe but the exhaust tone is so deep and mellow with a 3/4" exhaust I don't know if I will now.
 
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beltbuckle

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Aug 22, 2011
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Put a tachometer on today. RPMs at full throttle with the CVT in high are about 2900 RPMs. Might be some tweaking I could do to get more RPMs out of it?
 
NEAT TIMES

NEAT TIMES

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beltbuckle

It should last thru a couple generations at that rpm. Is the governor still hooked up!
Am fairly sure that 4000 would be fine, believe 3600 is normal.

You have built a swell motorized bicycle! It starts off with good power because of the variable cvt, but may still need more ratio for higher speed/rpm?? But if your satisfied, that is what counts. Waiting for my 2 bushings and cvt for my 140cc.

Ron
 
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beltbuckle

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Aug 22, 2011
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Meridian, ID
Governor has been removed. It'll do 3200 RPMs while accelerating but in high gear on the CVT during max. cruise it will only turn 2800-2900 RPMs. I kind of like the low RPM as it is pretty pleasant to listen to, but am probably leaving some power behind by being geared to tall. A bigger back sprocket may help, I think I am running a 56t on the rear wheel and a 10t on the CVT.
 
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