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Old 06-10-2013, 08:58 PM   #1
124hunter
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Default Big Twin Flathead chop

I will start with a little background on how I got to this point. A while back I posted a few pics of the Big Twin Flathead trike that belonged to my uncle. He passed away and I wanted to finish the rebuild he started several years ago. A couple of the members here helped me with some engine case issues I had and I got a local shop here in Tennessee to finish the trike. It turned out great but after a couple of rides I realized that I was never going to be satisfied riding it. I pulled the engine,trans and primary and posted the roller on craigs list and ebay.
I ended up trading the trike roller for the one in this thread. I have made a few changes and want to end up with something close to but not necessarily identical to an early '70s style bike. Please feel free to comment and critique as you see fit.

This is where my uncle had gotten to with the rebuild. It was basically the same but with a star hub front and cragar s/s back wheels and the tanks were blue with the rear box covered in blue vinyl(I was like twelve when he stopped riding I think):

I had "Panhead" Phils' Music City Motorcycle finish it out as I have experience working on cars and Jeeps but had never really done much with bikes. I did own a "TV chopper" about 10 years ago but that is a story for a different day. My iphone crashed and I lost all of the pics I had of the trike completed but this is the finished roller after yanking the engine and tranny:





If i had known that I wasn't going to be a trike kinda guy I probably wouldnt have spent the money to finish it but hindsight is 20/60. So I get a text from a local guy who says he has a trailer he would be willing to trade for the trike roller. I didnt know what I would do with it but told him to send me some pics. He also mentions he is going to take his shovel out of a little chopper project he has to put in the trike so I said how about roller for roller. He sends me a few pics of this:



So I meet up with him,super cool guy that agrees to swap my springer and front wheel for his and to switch as much wiring as he can to help me along(that was my biggest concern about trading as I didnt want to pony up for someone else to finish this bike too. MCM did a great job but I have figured out by reading this forum and others everyday for the last several months that I can do this.
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Old 06-10-2013, 09:07 PM   #2
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Default Re: Big Twin Flathead chop

So I bring it home and figure out what I want to do. I wanted to build it to resemble a a '70s style bike but not a bolt for bolt replica. I didnt like the paughco style tank so it was the first thing to go. I looked on ebay for weeks for a sportster tank like what i wanted but never really saw anything. I got a repop tank of ebay and I am open to suggestions on it. I also I am trying to figure out things like the sissy bar angle and how the z bars should be angled.




I have the engine and tranny mocked up along with the oil tank. I am going to do a different rear fender as the one on it is a pos:

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Old 06-10-2013, 09:13 PM   #3
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Default Re: Big Twin Flathead chop

I have the front motor mount shims made and also used an idea I saw on the JJ to build an oil tank mount:


I am hoping you guys can steer me in the right direction. I am not looking for opinions on what is "cool" or not but more of "they did 'this' in the '70s". I dont want to stray too far from where i am at this point:

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Old 06-10-2013, 10:01 PM   #4
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Default Re: Big Twin Flathead chop

I only see one problem.....

It's not mine. I want a BTSV real bad...

Do it proper.

Seriously, the clutch lever is too far from the fulcrum and will make that thing like an in and out box.

The sissy bar angle IMO should match the seat post angle.

I dig the invader, but miss the juice drum. (IF I was doing it it would have a big twin springer and a juice drum.)

Other than that, I dig it.
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Old 06-10-2013, 10:24 PM   #5
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Default Re: Big Twin Flathead chop

ermm that trike frame....is it the real deal? wheels thru time got a knuck trike , Im looking at the hoops at the front of the frame there , could be rare item
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Old 06-10-2013, 10:31 PM   #6
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Default Re: Big Twin Flathead chop

Jaws,I am not sure I follow what you mean by the clutch fulcrum point. Are you saying the shifter lever that is now my clutch pedal is too upright?


The spool front/invader rear is because I didn't like the 7 spoke invader front the PO had on the bike. As far as a juice drum rear the hub on the rear is set up for the disc. I want to get the rest of the bike sorted out and rideable as quick as I can and will fine tune it after a little shake down time.
The frame is powder coated a primer color gray that I plan on scuffing up and painting black. I loved the shovelhead build that ralphiejantz did earlier this year and specifically the AMF tank in black and gold. The BT springer on his build looked great but I want this build to be as close to what guys would have been doing around the time I was born.
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Old 06-10-2013, 10:39 PM   #7
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Default Re: Big Twin Flathead chop

Friday,the trike frame to the best of my dads recollection was the original frame that the engine came in that my uncle welded a servi car wishbone onto. He flipped the axle upside down to make it work with the 4 speed trans.


I had Mike Silvio at Cyclemos in Red Boiling Springs TN look the roller over and he said it looked like an original BT front section.He said that putting it back to a two wheel frame would cost more than I could just buy a frame for. Especially considering that the rest of the servi car section would be a tough sell by itself.
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Old 06-10-2013, 11:14 PM   #8
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Default Re: Big Twin Flathead chop

Quote:
Originally Posted by Dragstews View Post
My choice would be a 4" to 6" over, narrowed VL springer...
......Can ya Dig it......??? ......
(With a half Mini brake....Kinda looks like the K's front brake)
Dragstews, I smell what you are stepping in,you don't happen to have one of those tucked away in the back room of the world headquarters do you?

I don't know exactly what kind of springer I have now but figured it was a little more correct than the wide springer it had before. I appreciate everyone's input and would love to hear more ideas.
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Old 06-10-2013, 11:31 PM   #9
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Default Re: Big Twin Flathead chop

Yeah, the shifer lever is too far from the pivot. Move it down closer or as close as you can to the pivot and it will be easier to feather out.

I like your springer, It's nice and narrow. Needs a chopper stopper for the look if you want the front brake.

Maybe it's the rear caliper......Do you have a banana? That would look cool with the invader and be disc and period.

Either way. I love this bike.
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Old 06-11-2013, 01:19 AM   #10
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Default Re: Big Twin Flathead chop

Great start! I would lose the seat & rear wheel for a juice brake/spoked setup.. Here's a pic of Joe Lingley's recent build, one of the best 70's style flatheads around..

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Old 06-11-2013, 11:15 AM   #11
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Default Re: Big Twin Flathead chop

Wow Zeeman,that is what I am talking about,that bike is just about perfect. I love the black and gold paint. I am leaning more and more towards the juice drum set up,maybe not immediately but it will be in the plans. As far as the springer I like the narrowed VL idea also but want to ride this summer at some point. Anybody have an opinion as to which angle the z bars should be or would either way be "period correct"?
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Old 06-11-2013, 12:36 PM   #12
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Default Re: Big Twin Flathead chop

I like symmetry myself...
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Old 06-21-2013, 11:46 PM   #13
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Default Re: Big Twin Flathead chop

I am hoping someone can point me in the right direction on getting my BTSV set up properly in this frame. I made two shims for the front motor mounts a couple weeks ago out of 16 gauge sheet metal. After putting the rear bolts in and torquing them down I realized the front still had a decent size gap between the frame and the motor tabs. I made another shim for a total of three and then put the bolts in the front and tightened all four to see what I had.


The back side has less than .005 inch clearance.

The front side the feeler gauge barely slips under the front side mounts. Does this look right or should I be looking for less clearance on the front side mounts? Is there a shim set I can buy to get this dialed in a little closer if need be?
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Old 08-09-2013, 02:09 PM   #14
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Default Re: Big Twin Flathead chop

I have made a little more progress on the BTSV chop but not quite finished. Here are a few with the tank back from my painter. I remounted the seat to remove the gap between it and the rear fender. Speaking of the fender I shortened the one I had to use for the time being.







I am having a hard time with oil leaks. The feed line from the tank is the worst and into the motor isnt much better. That one is the only solid line. The vent and return lines i have about a 4" section of rubber line spliced in between as the flathead motor sits really low and the horsehoe is spaced up to fit closer to the upper frame rails. Still need a battery, drive chain and few other small things but I am almost there. Sorry for the hazy pics. I will grab a few more with a real camera when it is ready to ride.
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Old 08-09-2013, 03:21 PM   #15
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Default Re: Big Twin Flathead chop

If the frame was built for a Pan or Shovel the engine spacing will be way off. The FACTORY spacer as used on '48 ULs in wishbones is 3/8" thick. If it isn't right you will break your cases.
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Old 08-09-2013, 03:45 PM   #16
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Default Re: Big Twin Flathead chop

Quote:
Originally Posted by Rubone View Post
If the frame was built for a Pan or Shovel the engine spacing will be way off. The FACTORY spacer as used on '48 ULs in wishbones is 3/8" thick. If it isn't right you will break your cases.
I put a piece of 3/8 flat stock(not a factory style spacer) in between the front mounts and the frame before making the shims. The rear mounts were not torqued at the time and the feeler gauge test showed a lot of space when inserted from the front between each of the mounting holes.

Would there be a difference in the flat stock and the factory spacer if both are 3/8"? I definitely don't want to screw this up. The three 16 gauge shims are less than half of the required 3/8" spacer but there is (virtually) no gap when using the feeler with those in place. Thanks for the input Rubone.
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Old 08-09-2013, 04:59 PM   #17
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Default Re: Big Twin Flathead chop

I have to agree, that big honkin brake caliper and sportbike tire are killin the vibe. Otherwise pretty badass.
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Old 08-09-2013, 06:45 PM   #18
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Default Re: Big Twin Flathead chop

Quote:
Originally Posted by Richard D View Post
I have to agree, that big honkin brake caliper and sportbike tire are killin the vibe. Otherwise pretty badass.
Yup.
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