new project

GoldenMotor.com

Moto

Member
Jan 7, 2012
403
15
18
San Francisco, CA.
This is a frame I picked up a while back and have been really wanting to build it ever since. Ive been slowly gathering parts. Too much schoolwork right now to do any building which is frustrating, but after thanksgiving I get easier classes. Anyway - its a "sterling" frame, it would appear crappy at first sight because of the lack of brake bosses, but its from the very early days of mountain biking where caliper brakes were common. Its really heavy gauge tubing, and the head tube is this weird BMX size from the 70s and 80s. Its not 1/18 but oversized 1".
Its got really pretty welds and Im using some cool old schwinn forks, aria rims and hopefully some big old motorcycle levers. Also have this nice specialized quill stem and my favorite handlebars.
The seat came of a cool road bike somebody was tossing in my neighborhood. I think it looks really cool on this bike.
Here she is: (about 10 pounds as she sits above - heavy duty)


cool seat binder built into chain stays:



seat needs some snow seal but shows no cracks and is comfy


forks:


so I will be updating this build as it progresses. Ive got a headset on order from amazon but have pretty much everything else.

engine will be a modified 66cc china with dellorto carb, moped pipe, 39 t rear sprocket, and Im going to try my hand at modified port timing - probably mild motocross timing. should be fun

-Ethan
 

Moto

Member
Jan 7, 2012
403
15
18
San Francisco, CA.
Haha noticed something was missing.
What engine on your bike? I'm putting a arrow 4.5 : D
building up a nice bottom end I already have. its the same bottom end that dax sells which everyones obsessed with. Nice bottom end! may rebuild using nachi bearings. Currently spins well and buttery smooth. Im going to port my cylinder using Graham Bells blueprints - he seemed to have it all nailed down to a science. As for the head Im planing to use a puch head that I already have. I dont want very high compression - I want it to breathe well. I would love to get my hands on a puch water cooled head. Water cooled bikes just seem so ****ing sexy n racy n ****. I love arrows water cooled bike. anyway.....

Im gonna build an intake out of a bike steerer tube.

http://iheartstella.com/resources/manuals/tuning/Graham-Bell-Two-Stroke-Performance-Tuning.pdf
 

MotorBicycleRacing

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Jul 28, 2010
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I want it to breathe well. I would love to get my hands on a puch water cooled head. Water cooled bikes just seem so ****ing sexy n racy n ****. I love arrows water cooled bike. anyway.....
Arrow Motorized Cycles retired their water cooled head race bike.

The water cooling causes a couple of DNF's due to the electric water
pump being damaged in a crash and failing another time.

Dave made a mechanical water pump but water cooling a China girl is
too little gain for the complexity and other problems.

The Fred head with copper squish band by CR machine makes as much
power as the crank and bottom end can take at about 9.5 HP
 

Moto

Member
Jan 7, 2012
403
15
18
San Francisco, CA.
yeah I heard about that - bummer. I just like the idea of a water cooled china girl - kind of seems like the ultimate ironic oxymoron. Fred's heads are beautiful :D
 

Moto

Member
Jan 7, 2012
403
15
18
San Francisco, CA.
got this bike together today

headset was a pain in the ass to install
I am using:
vintage bull moose handlebars and some nice old xt brake levers
shorty 165mm cranks for ground clearance
nice metal throttle
single speed chain tensioner
I think it looks really good
this frame has ridiculously relaxed geometry which means its comfortable but doesn't really corner fast. Still I really like the way it rides. pics







 

Moto

Member
Jan 7, 2012
403
15
18
San Francisco, CA.
Worked on this some more got a lot done! Needs new cylinder and I have to make an intake still. Also have to setup the rear wheel but I have the parts. Sitting at ~45lbs right now goal is to have it 50 pounds dry! Gonna be tough but I think I can do it. Really desperately need gas tank suggestions bc I kinda hate the stock tank on this bike! Thx Ethan
 

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Moto

Member
Jan 7, 2012
403
15
18
San Francisco, CA.
that pipe is awesome!! how did you do that?
Its pretty simple really, take a moped pipe, cut the restrictor out of it, weld it to a section of curved pipe for the header, and then weld that to a flange. Just lots of welding. I dont have a welder but I weld wherever I can (ie friends houses / people who I know)

I actually got this thing running! working really well right now - just need to tune it. Also the intake I made puts the carb at way too steep of an angle so gonna play with that. Its quiet but needs the top of the cylinder lapped and a new head gasket. But its really high compression and *should* run like a top once dialed in
 

Moto

Member
Jan 7, 2012
403
15
18
San Francisco, CA.
Re: new project (new engine build)

the old engine ended up having sand in it! (i rode this engine on the beach at some point in its past, which was insanely fun but my air filter was not up to the challenge.) I tore the engine down, but one of the ****$y chinese bearings was stuck on the crankshafts journals, and I destroyed the crank trying to get it off. I dont have the equipment to true them up myself, so I figured why not just order a nice dax bottom end for my sake. its on its way right now - should arrive tomorrow or monday.

today I prepped up a nice top end, ported a cylinder, put some good rings on a piston from the old engine - keeping the same head:

did a lot of work on the transfers, and opened up the exhaust and intake.

head:


money shot with the whole top end together:


there has been quite a bit of experimentation going on around here XD