New BoardTrack Project w/Honda Engine

markeatmark · Oct 12, 2009

Briggs n Stratton cart motor/ JR. dragster motor has no fins on the fly wheel. mite be worth a look.
http://image.hotrod.com/f/9802510+w750+st0/hrdp_0308_01_z+briggs_and_stratton_engine+combustion.jpg

vrgt2003 · Oct 16, 2009

Haven't had a lot of time to work on the bike lately, but did get a Brooks B68 Saddle. Little smaller than what I was hoping for but what can you expect for $99.

Anyway, issue is moving the seat back toward the rear wheel while still keeping it low to the frame. Decided to fab a short post and tapped the end with a 3/8 tap.

There was a bracket already attached for holding the fender, beefed up the bracket, added more weld and attached the post to the bracket.

Looks like we are pretty close on the seat position.

A little different looking from the side, may have to add support to the front part of the carriage.

Mike

dmar836 · Oct 16, 2009

Mike,
The way I mounted mine was fairly simple, set the seat back, and is very similar to the original. With a couple tabs welded to the seat stays, you can support the seat from the rear while the original post position supports the front.
Great innovation. Welcome to uncomfortable!
Dave
KC

vrgt2003 · Oct 23, 2009

Got the new Worksman Wheels in. What a difference new wheels and tires make on a project like this.
Thanks to Board Track Racer and dmar836 for pointing out what great fit the Worksman Wheels are.

Plan on using a 48 tooth sprocket on the rear hub. This should give me a total 9.6:1 ratio from the engine output shaft which should produce a speed of 29 MPH @3600 RPM. Will need to develop an adaptor to attach the sprocket to the hub.

Found a Raleigh neck (stem) on Ebay, looks much better than the previous neck. Will need to find a good looking set of handlebars to go with it.

Trying to develop a kick starter using the jack shaft and a freewheel. The jackshaft is tied directly to the engine through the primary drive. Attached a freewheel to the end of the jackshaft and plans are to turn the freewheel with a crank arm and pedal. More to come next week on this.

Mike

tyrslider · Oct 25, 2009

Very inspiring crafstmanship! Is this bike going to have pedals?

vrgt2003 · Oct 26, 2009

Thanks, I appreciate the nod. We plan to use crank arms and pedals for more or less foot rests. We are planning on using the pedals as a kick start as well. Originally we had hoped to be able to pedal start the engine, but after we got the jack shaft in place decided this would not work out. Hope to have a little progress on this by the end of the week.

Mike

skullsaw · Oct 30, 2009

You will have to post a video of that thing in action when completed.

vrgt2003 · Oct 30, 2009

Ordered a new #41 48 tooth aluminum sprocket. Would have preferred steel but for the amount of fabrication we wanted we decided aluminum would be the best way to go.

Added 8, 1" lightening holes and 8 c'sinks for 5/16 flat head screws. Makes for a world of differnce in the look.

The hub adaptor is a neat piece of work. Thank goodeness for a CNC mill. This was fabricated from an aluminum block 5/8 thick.

The adaptor will bolt to the flange of the hub with 9, 1/4-20 flat heads. Clearance for the spokes added so we have a nice solid fit to the hub. Nut, washer, lock washer to secure it to the flange.

Left a ring of material proud on the adaptor to locate the sprocket bolted with the 8, 5/16 Flat Heads. The sprocket ends up being pretty close to flush to the end of the freewheel mount.

Mike

azbill · Oct 30, 2009

nice

don't see many rear drums because of the mounting issues
(^)

vrgt2003 · Oct 30, 2009

Put the wheel back on and added the drive chain for a quick look. Proportions of the sprockets seem to look about right. Hopefully the ratio will have enough power for descent aceleration.

Played around with a few concepts on making the engine look vintage. Plan to add few extra "fins" and a "Flat Head" look to it. Here is the mockup. Also added the rear fender. Found one with a pretty neat rib in the center.

We knew that we would have some interference problems with the sprocket/chain and rear stays. Currently looking at what will be the best fix for this. More than likely we are looking at major surgery to get sufficent running clearance for the sprocket/chain.

Did get new handlebars, looked at several styles, but ended up with one that is identical to the original. Don't know, just seem to be the right fit for it.

Mike

Board Track Racer · Oct 31, 2009

"There you go!, thinking outside the HUB again". Nice idea, looks like a project for marketing on that spocket adapter? Like the way everthing is falling together for you. The Worksman rims, ...gotta love 'em. Glad to see you took off about 2 lbs. of weight on that Jackshaft sprocket, "Drill it" to match the rear. The bike has a nice stance, as always I look forward to more pictures of your progress. .weld

.

vrgt2003 · Nov 3, 2009

In order to fix the running clearance with the new sprocket, we started with a pie cut to the lower tubes and forcing a block between the lower tubes until the dimension needed and tack weld in place.

We cut away the original fender bracket and cut the upper tubes away from the seat tube.

Pie cut the upper tubes just beyond the sprocket, extended the upper backbone tube past the seat tube. Fabricated spacer to space out the upper wheel tubes and welded back in place.

Fabricated a new curved tube to attach the fender and welded between the upper wheel tubes.

Mike

vrgt2003 · Nov 3, 2009

As a result of the changes to the rear for running clearance the seat post was moved forward and the backbone of the bike extended.

Mike

dmar836 · Nov 3, 2009

Looks the part from behind. Once you build one with a few considerations for a motor, reduction, durable hub, etc. you see these frames were actually quite a bit different from a bicycle frame. Imagine if you had to support 40+HP!
What surprised me when I saw pics of Jeff Decker's Cyclone was how wide the rear spacing was. Nice job!
Dave
KC

markeatmark · Nov 3, 2009

vrgt2003 said:
As a result of the changes to the rear for running clearance the seat post was moved forward and the backbone of the bike extended.
View attachment 15386 View attachment 15387 View attachment 15388

Mike

Just guessing but that sucker is going to be fast. looks cool man.

vrgt2003 · Nov 6, 2009

Fabricated a kick starter sprocket component. This component will secure to a pedal shaft.

We are using a piece of the roller chain that is secured to the partial sprocket.

Fabricated a new pedal shaft bracket with bushings for a 3/4" shaft.

Welded the bracket in place right behind the original bottom bracket.

Added a crank arm and pedal to one end of the shaft and slipped the shaft through the bushings.

Mike

vrgt2003 · Nov 6, 2009

Secured the kick starter sprocket to the pedal shaft and attached the right pedal & crank arm.

The kick starter sprocket engages the freewheel so you can rotate the pedal up to make ready to turn the engine over by "kicking" down on the pedal. The kick starter sprocket will disengage with the the freewheel after "kicking" down on the pedal.

Both the left and right crank arms are secured to the pedal shaft so you could use either pedal to kick start the engine.

We found that leaving the pedals free to rotate was actually very comfortable to position your legs and feet while riding the bike. We had planned to add a feature to lock the pedals in place, we don't feel we will need this.

Mike

sharkster · Nov 7, 2009

Hello,
I looked at all the posting of your great job. I just found this site today after doing alot of surfing. I want to build a street legal boardtracker along the lines and theme of yours. I am retired 66 years and can do some fair fabrication. I have built hot rods, race bikes etc. I raced professional AMA when I was younger and always loved the start of motorcycle racing, which was the boardtracker. I don't want to reinvent the wheel. Your project has given me great ideas. Anything in the way of guideance and wisdom would be apprciated. Parts link etc. Thanks and what a great job. Hal Stockton, San Antonio, TX

dmar836 · Nov 7, 2009

Hal,
Welcome. Lots of great builds on the BoardTrackers part of the forum.

Mike, I thought your clutch would disengage the pedals/drive from the engine primary reduction. If so, how would you kick start it through the jackshaft without having to exceed the RPMs of the clutch?

Dave
KC

vrgt2003 · Nov 9, 2009

Thanks for the comments, we have had a lot of fun with this project. I guess this is why we post pictures of the progress of the build, we know there are people who can appreciate the little details of a project like this.

Be happy to add my 2 cents to your project. The first thing I would recommend is to select the engine you want to use and build a custom frame for it. We started with a bicycle frame and this has caused a little grief from time to time. Get the layout of the frame proprotionally right to the engine and wheels.

Let us know what your post title is so we can keep up with what you are doing. Good luck with the build.

Mike

New BoardTrack Project w/Honda Engine

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