First Build: Roadmaster Board Track Racer Tribute

KeithSeymour

KeithSeymour

Active Member
Well guys, it's finally time I post a build thread. I grew up around bikes as I'd piece them together and trade parts with friends and my first job was assembling bikes at the local bike shop. When I got my license at 16, my focus turned to cars and wrenching with friends to make them go faster. With the passion I've had for bicycles and then motors, I wanted a new project without the garage space and cost of another project car. I've been observing and researching this site since last fall with the goal of building a fun, sleek looking board track racer inspired motorized bike. As my first one, I loved tinkering with it and getting everything going as I worked out the kinks. A huge thanks goes to MotoMagz for selling me a lot of his old setup and helping me along the way as I pieced the rest together to get it going. Still working out little issues with it (Free tip that I can't understate: USE A LOT OF LOCKTITE!)

Here's a list of my parts:
-1950s Road Master frame (actually a repop from 80s)
-Custom in frame gas tank
-Lucky Seven laid back seat post
-Geyes Springer Seat
-Sunlite Deluxe Monark style springer fork
-11 guage spoked Worksman front drum wheel and rear weinnman alloy/ shimano cb110 coaster brake (set up now)
-97.7cc lifan flathead 4 stroke motor with vintage plug wire and wrap around rope start
-Sick Bike Parts Motor Mount
-Affordable Go Karts Jackshaft plate and reduction gears
-Max Torque Centrifugal Clutch
-wide crank set from a kit
-jackhammer style motorcycle throttle and grips
-Kevlar belted, thorn resistant tires
-Sportsman flyer 56 tooth sprocket and hub adapter

Without further ado, here are some pictures of it….

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It's actually out of commission right now because I broke some spokes when my hub adaptor bolts vibrated loose. You can also see in the pictures that my coaster brake arm bent all the way around. Had the LBS install some new spokes just haven't had time to put it back on.

Here are some things I'm hoping to do to make it better:
Touch up some of the paint I scratched while installing everything.
Lace up MotoMagz' SA 5speed hub I bought off of him to my other Worksman rim (need right spoke length) and install rest of shift kit.
Install an adjustable carb and a different throttle linkage (stock doodlebug works but sucks for throttle response and adjusting)
Vintage style but functional headlight

Thanks to everyone else who has helped me along the way and will continue as I keep tinkering with this newfound hobby!

Keith
 
As Silverbear would say, "I concur"! I have thought about doing away with my recoil start rope and set up an old style rope start like yours, but am concerned about it being a pantleg catcher. Nicely done!

Dan
 
Glad the bike got a second life. Like I said it was one of my favorites and still is!You did a good job on your first build. Now hopefully you will get the 5 speed shifted set up. It is lots of fun...
 
Thanks guys for the encouraging words!

Tinsmith said:
As Silverbear would say, "I concur"! I have thought about doing away with my recoil start rope and set up an old style rope start like yours, but am concerned about it being a pantleg catcher. Nicely done!

Dan
Click to expand...

Dan, I'm more worried about the open chain from the clutch to jackshaft on the other side than the rope pull. The rope pull has a lot less to get snagged on since it's pretty smooth.
 
I'm running a jackshaft with no cover on the same engine, it's never caught my pantlegs. I have felt my bare legs get close to the clutch drum when wearing shorts, but it's never hurt me. A more serious problem, which you've already addressed, is the heat from the exhaust. I just ordered 5 feet of exhaust wrap from treatland. They sell it by the foot for $1.60 a foot and it's black. As soon as it gets here I'm gonna wrap mine and then I won't need to worry about burning my legs anymore. In pants I'm fine, but in shorts I can really feel the heat.
 
Keith:

A very nice build, thanks for the pics.

Swapping a cable ready carb on to that engine is simple. Either the NT or RT on a round manifold, or a PZ style on a flange intake

99Int1.jpg


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Either carb works better than the original unit, and a standard throttle cable fits.

.
 
Very cool build. Nice to see one finished. I will be there hopefully by the end of the month. What sprockets did you use? I am doing the 10 to 25 to 11 to 48 - final ratio 10.9 . I am hoping that moves alright. Once again very cool friggin build!
 
Moisstink said:
Very cool build. Nice to see one finished. I will be there hopefully by the end of the month. What sprockets did you use? I am doing the 10 to 25 to 11 to 48 - final ratio 10.9 . I am hoping that moves alright. Once again very cool friggin build!
Click to expand...

Thanks for the complements everyone!

I'm using 11t (clutch) to 22T input and 9t output to 56t rear sprocket for a 12.44:1 ratio. It moves pretty good with that and I'm a big guy at 280, 6'4" I really don't have anything to compare it to as I'm used to pedaling and this is my first motor bike.
 
FFV8 said:
Keith:

A very nice build, thanks for the pics.

Swapping a cable ready carb on to that engine is simple. Either the NT or RT on a round manifold, or a PZ style on a flange intake

99Int1.jpg


99Int5.jpg


Either carb works better than the original unit, and a standard throttle cable fits.

.
Click to expand...

So with the NT or RT, I don't need a throttle linkage because they're "cable ready"? Would I need to fabricate a manifold for it or is there anything that bolts up directly?

I have a GC160 carb in the works but understand I need to get the AGK throttle linkage to make it work.
 
KeithSeymour said:
So with the NT or RT, I don't need a throttle linkage because they're "cable ready"? Would I need to fabricate a manifold for it or is there anything that bolts up directly?

I have a GC160 carb in the works but understand I need to get the AGK throttle linkage to make it work.
Click to expand...

No linkage required with either carburetor. The standard China Girl cable snaps right in.

The manifolds are production parts, listed here:
http://motorbicycling.com/showthread.php?t=55050

B
 
I did the flathead setup for over a year. This engine is probably great for a shifter setup, but not great for single speed. Top speed was great for cruising, but climbing ability left a little to be desired. I also agree that the stock carb is not the best. The engine ran much better with a mikuni pz19 carb. Since I didn't want to go through the hassle and expense of installing a shift kit, I decided to upgrade to a 79cc Harbor Freight engine and gear it for 30mph. Since the 79cc makes about 1000 more rpms, I should have good climbing ability with that gearing. Anyway, I ramble. That's a very nice bike, good luck with completing it.
 
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