Hey guys!

[wret]

Almost done with my project of building a board track racer with a Zongshen engine. I have a some questions that maybe one of you could answer.

1. The port near the spark plug on the cylinder head. What is it? I see in some pictures its blocked off.

2. Two vacuum ports on the intake manifold: what would they typically be routed to?

3. Crank case vent hose: Where is it routed?

Here's a pic of my bike. Thanks guys!

[culcune]

Wow--fantastic project! What size engine, and which model (i.e. fml169, etc).

[FastDoc]

Fantastic project indeed.

The port by the plug is for emissions control. Make a plate to block it off.

The vacuum lines are also EC nonsense, block them off.

The crankcase vent is either routed to the atmosphere or the airbox. In your case install a little filter on it and you are good to go.

Your project and your artistry will be greatly appreciated here.

[Weldangrind]

Welcome!

It's like you're reading my mind! I've had a project like that in mind for some time, but I lack your mad skills.

Since you're going for a period correct look, I'd forget about the filter and just route the vent hose behind the engine, and point it at the ground.

Do you plan to run a battery? If not, you might be able to fabricate a block-off plate and remove the starter.

Did you fabricate the frame? Where did you source the rims and tires? Please share some more details about this terrific build.

[SpudRider]

Welcome; we are glad you joined us. Thanks for posting the photo; I love your bike.

[wret]

Thanks for the compliments guys! Your help here is greatly appreciated.

I will hide the battery in a faux oil tank on the seat tube (almost done).

Here's a little more info about the bike. I started with a Worksman bike frame, which has a reputation for durability and a 500 lb capacity rating. I replaced the three center tubes with 12 gauge chrome-moly tubing that I bent with a harbor freight pipe bender. Here's a pic of the frame and "jig".


The wheel hubs are from an old Puch moped and are laced with 11g spokes and heavy steel rims from Husky. The tank is from an oxygen cylinder, cut lengthwise and widened.


I made the seat pan from fiberglass and covered with leather from Tandy (I was almost in over my head on that little project).

[wret]

Oh, and its a 162fmj - 150cc engine. Originally I was looking for one WITHOUT electric start but found this one for a decent price. As it turns out the foot crank would be in the way of the pedals, so its just as well.

[SpudRider]

You did a beautiful job. Your fabrication skills and patronage of Harbor Freight confirm you are a kindred spirit with most members of these forums.

[zingshoen]

fantastic project, will be a beautiful bike. you ll be riding it on a track?

ikonikmoto announced a somewhat similar model, but it doesn t seem to be available. seems like yours is a better build and certainly a better engine.

[Weldangrind]

The use of an oxygen cylinder is genius. I presume it's steel; did you MIG or TIG weld it?

The frame looks to be MIG welded. How did you determine the graceful arc that accomodates the motor?

Was the front end taken from an existing design, or did you fabricate it from scratch? How did you calculate the steering angle and fork length? When the rear wheel is on the ground, my guess would be that the top tube is parallel to the ground; that obviously took some math.

I had never heard of Husky. Any advantages over Buchanan's?

[wret]

The tank is aluminum, surprisingly easy to cut on a table saw. I traded a box of steaks to have it TIG welded. The frame is MIG welded, mostly by me but with the assistance of a buddy who just took a welding course. The frame shape is taken directly from pictures of 100 year old Indian board track racers.

Yes the top tube is almost parallel to the ground. Just a bit of slope up toward the front. The front fork is a Monark springer of a heavier design recommended for motorized bikes.

I drew out the shape on the board you see pictured and calculated the head angle carefully before bracing the the head tube in place. I added a bit of extra trail so hopefully I err on the side of increased stability.

Husky is a maker of of heavy duty bikes and parts similar to Worksman but with easier online purchasing. Very economical prices.

[FastDoc]

I'm at work and don't have the time to put into words how impressed I am with what you are doing. I am glad you joined us. Please keep us up to date with the rest of your project.

[wret]

Originally Posted by zingshoen

fantastic project, will be a beautiful bike. you ll be riding it on a track?

ikonikmoto announced a somewhat similar model, but it doesn t seem to be available. seems like yours is a better build and certainly a better engine.

My original concept was to keep it as close as possible to an early board track racer, complete with a separate pedal crank in a coaxial shaft at the bottom bracket. But I intend to ride this bike on the road and by the time I finish it will need all the safety equipment necessary to pass state inspection: lights, horn, etc.

Here's a pic of the most complicated part of the whole build; the coaxial shaft or "quill shaft". The pedal crank rides inside the drive shaft on a separate set of bearings.

[Weldangrind]

Where did you find a sprocket setup like that?

[wret]

Originally Posted by Weldangrind

Where did you find a sprocket setup like that?

A piece here, a piece there...

The sprockets are for a kart application. Easy to find in whatever size you need and fairly cheap. Conveniently, lots of gokarts use a 40mm axle which is large enough to fit another shaft inside and 40mm bearings abound on ebay.