Custom Frame For Thumper Motor

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culvercityclassic

Well-Known Member
Sep 27, 2009
3,115
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Culver City, Ca
This is my attempt to build a one off custom frame for the Dyno Thumper. http://motorbicycling.com/f41/dyno-thumper-28189.htmlThe original plan

Well it is not considered a Dyno Thumper anymore now that I will be building a custom frame for this HF motor.

I have wanted to build a one-off custom frame for awhile and now is the perfect time to do so with this motor. I have gathered all the material and started with the drop outs, I made them out of 3/16 plate.

I picked up 20 feet of ½, ¾, 1, 1 ¼, and 1 ½ .065 tubing. I purchased a tube roller from HF and have another hydraulic bender to use; I also have a tubing notcher. I ordered head tube and bottom brackets that are really impressive, the quality is unreal.

I keep looking on Rat Rod Bike website for ideas and found some really cool home built frames. I will be going for old school Rat-Bobber-Drag Bike style. This is the look I really like....
Falcon Motorcycles : Hand Made Motorcycles Custom Designed Around Rare Iconic British Engines

I will keep this post going as I progress….
 

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sportscarpat

Bonneville Bomber the Salt Flat record breaker
Jun 25, 2009
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california
Hi Jeff,
Welcome to the frame builders club. Time to start cutting, notching, rolling, etc. I bought that same tube roller with dreams of making my own drop loop down tubes. Found out a few things quickly. As you roll the tube tighter and tighter the ends will start to bend away from each other. What I mean by that is it is next to impossible to roll a ring shape because by the time the ends get near each other they will not meet but will be offset. The less you roll the less the problem. Once you roll a tube lay it flat on the floor and you'll notice the problem. It can be overcome but not without a lot of hard work. Next big problem may or may not affect your build depending on the shape of your finished tubes. It is almost impossilbe to roll into and out of opposing curves without tube deformation. You can't even transition from a curve to a straight with that tube roller without very noticable tube deformation. You'll have to roll beyond what you need, cut back to the end of the bend, then weld a straight (sleeved and plug welded of course) and then finish out the tube by grinding. People can look at one of my drop loop down tubes and see a nice flowing shape with two different radius curves and two straight sections, but all I can say is they have NO IDEA how difficult it is to make a tube like that. On my frames the down tube IS the frame. All the other bends can happen in a tube bender instead of a roller. Keep us posted and hopefully you'll find solutions to these problems. Don't get me wrong here as I don't want to discourage you in any way, just a heads-up with what I discovered with the HF tube roller.
Pat
 
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culvercityclassic

Well-Known Member
Sep 27, 2009
3,115
177
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Culver City, Ca
Thanks for the input Pat, I did try it on a piece of conduit and found out what you mentioned.

I am going to start on the Frame tomorrow…we shall see what I come up with….
 
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culvercityclassic

Well-Known Member
Sep 27, 2009
3,115
177
63
Culver City, Ca
I spent a couple of hours working on the rear triangle of the frame. I have a crazy design I am working on based off a well known bike builder: Jesse Rooke Customs This bike will be able to handle a fat ass tire for sure.....

I am having a blast with this so far…Miller and myself are getting along well.

Tomorrow I will start the front section and roll some 1 ½ tubing.
This bike is going to be crazy…..
 

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The 26incher

The 26incher

New Member
Dec 19, 2009
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Pepeekeo, HI
IMO, Rooke's bikes are some of the best out there. Big ups Jeff! Do you think you could help me with a project I have? I'll buy everything and pay for your time.
 
corgi1

corgi1

New Member
Aug 13, 2009
2,272
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KCMO
culvercityclassic said:
I spent a couple of hours working on the rear triangle of the frame. I have a crazy design I am working on based off a well known bike builder: Jesse Rooke Customs This bike will be able to handle a fat ass tire for sure.....

I am having a blast with this so far…Miller and myself are getting along well.

Tomorrow I will start the front section and roll some 1 ½ tubing.
This bike is going to be crazy…..
Click to expand...
Just replacing the rear triangle w/a wide one would solve a lot of problems
 
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culvercityclassic

Well-Known Member
Sep 27, 2009
3,115
177
63
Culver City, Ca
I found little time to work on the frame, the design and figuring out the lay-out and notching angels are a _itch. The bottom drop loop will be 1 ½ tubing to hold the bracket for the beast of a motor.

I have been studying lots of bikes but always fall back to Rooke Customs; if you look at my past bikes you can see how I like the tanks. Rooke Rules

Not sure how much I will get done this week due to the death race; I need to take my
time.

26 incher…I will weld that project for you no problem, I have the metal too.

I Ride Customs…The tubing roller is OK for the price, don’t expect miracles from it. Read Pats post.
BTW: I am also chevelle68 on Rat Rod Bikes. I sent you the PM
 

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flex man

New Member
Feb 24, 2011
253
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Woodland Hills Ca.
Hey Culver
Great job. I had no idea about this builders forum I love it . Your giving me some real inspration
I guess I will have to break out the tube bender and notcher. Your Quite the fabricator .
Really awsome work . When we were at that bar I wish we could have talked about
fabricating .I had no idea you were into this level of work..I have all these tools but I lost my mojo. After seeing all this . You guy are really getting my juices flowing again. So Thank You All for inspiring me to get off my *** and getting back into the shop again..for awhile I was burned out ..I had to do this for a living when I was building electric stuff for a company called
Hybrid Technologys..Constantly under deadlines To get stuff out for shows and stock holders...It was a nightmear sometime. being under the gun to create thing that were never done befor. nobody to ask questions as it was all new technology at the time.....Flex...
 
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flex man

New Member
Feb 24, 2011
253
1
0
Woodland Hills Ca.
Sorry I cant untill I get the OK from company producing it...Soon I hope...Flex
did you mean shifter? Tools? Bender? as far as a frame . Just starting to think of a project...
 
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streetstrip80

streetstrip80

New Member
Oct 12, 2008
73
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Littleton, CO
Looking good!
Rooke was one of my strongest inspirations
What is that motor? my latest build I think is a thumper(by the sound and torque, but it is a 2-smoke, and I always thought thumpers had to be big 4 strokes)
check it out in the DIY thread "will this work"
 
scotto-

scotto-

Custom 4-Stroke Bike Builder
Jun 3, 2010
6,505
25
38
Ridin' inSane Diego, CA.
culvercityclassic said:
Streetstrip80: Its a HF 6.5 Hp four stroke "El Cheapo"

The add on parts is what cost the money...
Click to expand...
El Cheapo is gonna be Bad Co.....it's lookin real nice so far Jeff! Is the engine gonna sit down in the loop a bit? I'm seeing a few possibilities so far, keep it coming!

dnut

note: what a great weekend, had a blast and glad everyone made it home safe!
see ya soon.
 
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culvercityclassic

Well-Known Member
Sep 27, 2009
3,115
177
63
Culver City, Ca
The motor turned vertical should not be a problem; I plan to add a little extra oil. In principle we are just trying to keep the bearings and rod lubed. This motor has no oil pump to starve.

It’s the cooling is what concerns me since I have removed the entire sheet metal shroud.
 
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