Keystone Flyer

GoldenMotor.com
S

sportscarpat

Bonneville Bomber the Salt Flat record breaker
Jun 25, 2009
1,844
485
83
california
Hi Guys,
Finally putting some steel to an idea I have been kicking around for awhile. I have always liked the Keystone style boardie frames. I am not an expert on the design but do see it's potential. It's basically an engine mounting cradle that connects from the frame bottom bracket to the down tube, tying these points together, then has attachment points for the engine. It also simplifies the down tube, which on my typical builds is two opposing bends of different radius that are a challenge to bend.

Here is the mocked up Keystone engine cradle next to a partially built frame. Plates are 3/16" stainless and frame tubes are all .120" wall DOM. Lugs are yet to be brazed in this photo.


Keystone Flyer by Sportsman Flyer, on Flickr

Underside detail of the Keystone engine cradle weldment. Lot's of little pieces all laser cut and tig welded together.


Keystone Flyer by Sportsman Flyer, on Flickr

You can see in the drawing where this is going. I was able to lower the engine in the chassis, and move it forward. I also left clearance for an electric starter. Thinking of running a stroked HF212 so in the 230cc capacity. It will also be one of the new free breathing Hemi heads. Frame should be a real ground scrapper. Easily the deepest, lowest loop I have built to date. I am pretty excited about this design. I also have a Briggs Keystone cradle in the works for this same frame. Gives added engine choices for the same chassis.


Keystone Flyer by Sportsman Flyer, on Flickr
 
Crazy Horse

Crazy Horse

Dealer
Feb 20, 2009
1,153
4
36
USA
Pat, as always you've raised the Bar so to speak for The Board Track Racer style of Build.

You have always explained your work in detail describing where what and who, this design It's truly a work of Art when you can emulate these machines from 100 years ago.

Pat, as you know and other forum members know I have been researching and obsessing for the last 4-5 years learning as much as I can about the Original Motor Bicycles & Board Track Racers.

For those of you who are interested in more History about these style of frames, also known as "The Marion Frame" which is the name that Indian Motorcycle Company called they're style of this frame.

MORE HISTORY:

The 1919 Indian racer that appeared at the Marion, Indiana Labor Day race featured a "keystone" style frame; henceforth, Indian's version of this style of chassis was known as a "Marion frame."

Harley-Davidson pioneered the use of the "keystone" frame in their successful 1916 win at the Dodge City, 4th of July 300-mile race.

The keystone frame was actually a modified loop frame with the bottom of the loop cut away.

This allowed the engine, supported by plates, to act as a structural member of the chassis.

Although Harley-Davidson's success at the 1916 Dodge City race was due to various innovations (8-valve engine and hemispherical combustion chambers, for example), the improved handling characteristics of the lowered engine position prompted Indian to follow suit.

Thanks, again Pat...

Peace Crazy Horse.


sportscarpat said:
Hi Guys,
Finally putting some steel to an idea I have been kicking around for awhile. I have always liked the Keystone style boardie frames. I am not an expert on the design but do see it's potential. It's basically an engine mounting cradle that connects from the frame bottom bracket to the down tube, tying these points together, then has attachment points for the engine. It also simplifies the down tube, which on my typical builds is two opposing bends of different radius that are a challenge to bend.

Here is the mocked up Keystone engine cradle next to a partially built frame. Plates are 3/16" stainless and frame tubes are all .120" wall DOM. Lugs are yet to be brazed in this photo.


Keystone Flyer by Sportsman Flyer, on Flickr

Underside detail of the Keystone engine cradle weldment. Lot's of little pieces all laser cut and tig welded together.


Keystone Flyer by Sportsman Flyer, on Flickr

You can see in the drawing where this is going. I was able to lower the engine in the chassis, and move it forward. I also left clearance for an electric starter. Thinking of running a stroked HF212 so in the 230cc capacity. It will also be one of the new free breathing Hemi heads. Frame should be a real ground scrapper. Easily the deepest, lowest loop I have built to date. I am pretty excited about this design. I also have a Briggs Keystone cradle in the works for this same frame. Gives added engine choices for the same chassis.


Keystone Flyer by Sportsman Flyer, on Flickr
Click to expand...
 
S

sportscarpat

Bonneville Bomber the Salt Flat record breaker
Jun 25, 2009
1,844
485
83
california
Crazy Horse said:
Pat, as always you've raised the Bar so to speak for The Board Track Racer style of Build.

You have always explained your work in detail describing where what and who, this design It's truly a work of Art when you can emulate these machines from 100 years ago.

Pat, as you know and other forum members know I have been researching and obsessing for the last 4-5 years learning as much as I can about the Original Motor Bicycles & Board Track Racers.

For those of you who are interested in more History about these style of frames, also known as "The Marion Frame" which is the name that Indian Motorcycle Company called they're style of this frame.

MORE HISTORY:

The 1919 Indian racer that appeared at the Marion, Indiana Labor Day race featured a "keystone" style frame; henceforth, Indian's version of this style of chassis was known as a "Marion frame."

Harley-Davidson pioneered the use of the "keystone" frame in their successful 1916 win at the Dodge City, 4th of July 300-mile race.

The keystone frame was actually a modified loop frame with the bottom of the loop cut away.

This allowed the engine, supported by plates, to act as a structural member of the chassis.

Although Harley-Davidson's success at the 1916 Dodge City race was due to various innovations (8-valve engine and hemispherical combustion chambers, for example), the improved handling characteristics of the lowered engine position prompted Indian to follow suit.

Thanks, again Pat...

Peace Crazy Horse.
Click to expand...

Hi Joe,
As always, thanks for the valuable information. Your knowledge with vintage motorcycles helps us all in our builds! In my personal journey into the design of vintage style motorcycles I feel I am rediscovering what was common knowledge 100 years ago. Reduction drives, fork design, frame design, engine mounting, brazed lugs, all of it was done for a reason. After building a few frames I begin to understand the reasons.
On another note, to me some of the most impressive art work from the era is captured in the blueprints these guys produced. Hand drawn with incredible detail and there is always a signature on the drawing. Someone sat down and created these drawing by hand. No CAD program, no CNC machining, heck they didn't even have a phone or email to order parts!
 
chainmaker

chainmaker

Well-Known Member
Jan 19, 2010
2,634
69
48
Ma USA
Now you did it, the bar has been lifted...again. Great looking start, I like the fact that you will be doing a Briggs version will it be for the old flatty style or the newer ohv ?
 
2door

2door

Moderator
Staff member
Sep 15, 2008
16,302
175
63
Littleton, Colorado
As always, nice work, Pat. And I hear that some congratulations are in order. Or am I letting the cat out of the bag too soon?

Tom
 
S

sportscarpat

Bonneville Bomber the Salt Flat record breaker
Jun 25, 2009
1,844
485
83
california
2door said:
As always, nice work, Pat. And I hear that some congratulations are in order. Or am I letting the cat out of the bag too soon?

Tom
Click to expand...
Couple more days on that, but here is a primer. It only took ten minutes to mount this little HF79cc four stroke engine to a bicycle frame. Used a pair of pliers, an allen wrench, and a 9/16" wrench. Then I had a cold one.


HF79cc Mount by Sportsman Flyer, on Flickr


HF79cc Mount by Sportsman Flyer, on Flickr
 
Slimey1

Slimey1

New Member
Mar 10, 2014
28
0
0
Mt.Vernon,OH
sportscarpat said:
Couple more days on that, but here is a primer. It only took ten minutes to mount this little HF79cc four stroke engine to a bicycle frame. Used a pair of pliers, an allen wrench, and a 9/16" wrench. Then I had a cold one.


HF79cc Mount by Sportsman Flyer, on Flickr


HF79cc Mount by Sportsman Flyer, on Flickr
Click to expand...
You deserve a couple cold ones(or 6 lol). What is your experience with the HF 79cc? What kind of top speed are they capable of with your frames? I'm asking because I work with a guy who has a 79cc HF engine for sale. How difficult would it be to mount a 420cc HF engine to your Keystone frame?
 
Lurker

Lurker

New Member
Jan 29, 2010
403
133
0
Pittsburgh
Keystone and Marion frames are hands down my favorite. I love your work and I can't wait to see how these turn out. Keep up the good work.
 
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