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Building a Big Twin Flattie from Bare Cases

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MarkBranst

Posts: 349

Joined: Thu Jun 24, 2004 12:01 am

Location: Champaign-Urbana, IL

Post Mon Nov 24, 2014 2:47 pm

Building a Big Twin Flattie from Bare Cases

Ok, I've finally got a good set of mismatched 42/40 U cases and a good late cam cover that wants to be a whole motor. Plan on aftermarket aluminum heads, and new cylinders (whenever they become available again). My question is this ... Given that there are repro internal parts for nearly everything engine-related, are there some parts that I should really try to find as originals (like rods) or does it matter? What repro parts should I stay away from? Or does it matter? Are there new and improved bits and pieces (like the European oil pumps) that I should be looking for?

Any input would be appreciated ...

Mark
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fhsmith1

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Location: Georgia

Post Mon Nov 24, 2014 5:41 pm

Re: Building a Big Twin Flattie from Bare Cases

Mark,
I did almost exactly what you are doing. It was a long, expensive project. Many will give you advise. I'll offer you what happened with my flywheel/rod assy.

I got them from Vtwin. They looked fine from outward appearance so I took them to an "expert" at the old iron with the cases. Case needed some welding and the left side bearing race replaced. All that was done and flywheels clearanced, and installed in the case. I thought all was right with the world. Like you I had to wait until cylinders/piston set came available. That took 2 years. when the cylinders/pistons finally got there and I went to install them, the pistons would hit the flywheel before coming to bottom dead center. Turns out the rods were over head valve, way shorter. After much arguing Vtwin did provide another set. The replacement set did have the correct rods but there was a LOT of rod side clearance almost 1/8" and the wrist pin bushings were machined with about
.005" clearance to the pin. My "expert" took them apart, fabricated washers to take up the slack between the rods and flywheels, seems to me he used washers out of a Shovelhead. replaced the rod pin set and wrist pin bushings. Bike has been running slick about 4 years now. I too got an oil pump from across the pond.
Good Luck
F
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knucklebolt

Posts: 330

Joined: Tue Feb 12, 2013 8:27 pm

Location: Six miles East of Cheney, Wa.

Post Tue Nov 25, 2014 10:10 pm

Re: Building a Big Twin Flattie from Bare Cases

You guys got grit, I started with a complete, rebuilt engine (minus generator) and that involved a few hours. !! Of course I just kind of duplicated what I would have built back in the day, for riding anywhere and everywhere. Are you doing/replicating a stock bike? That is certainly a bigger project.

One plus for starting from scratch, at least you know what's inside the engine when you are done. I didn't know if my engine was built by someone who knew what they were doing, or a drunk monkey. After 1000 miles it's running nice and strong, no smoke, no funny noises, so I'm kind of ruling out the drunk monkey.

I'm thinking that getting everything put together right, balanced, and checked and double checked and triple checked might be more important than the source of the parts. Improving the oiling certainly makes sense...and aluminum heads make a lot of sense if one is actually going to ride the bike a lot, or run anything higher than very low compression.

k.
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45Brit

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Post Tue Nov 25, 2014 11:56 pm

Re: Building a Big Twin Flattie from Bare Cases

My Ariel 45 project didn't start from bare cases but it HAS involved a LOT of time and effort. If I'd known quite how much, I would never have started.
Shoot, a man could have a good weekend in Dallas with all that stuff...
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Pa

Site Admin

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Location: Ohio USA

Post Wed Nov 26, 2014 7:13 am

Re: Building a Big Twin Flattie from Bare Cases

I love the later visor headlight and front forks combined with the hardtail and classic Big Twin Flatty engine blended into a real eye catching Bobber.
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45Brit

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Post Wed Nov 26, 2014 9:40 am

Re: Building a Big Twin Flattie from Bare Cases

Harley parts from the iron engine era go together in almost any combination, don't they?
Shoot, a man could have a good weekend in Dallas with all that stuff...
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Pa

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Post Wed Nov 26, 2014 2:09 pm

Re: Building a Big Twin Flattie from Bare Cases

They sure do.
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Frankenstein

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Location: Interlaken, NY USA

Post Wed Nov 26, 2014 8:33 pm

Re: Building a Big Twin Flattie from Bare Cases

I've built several BTSV's from bare crankcases in the last couple of years, here are my observations.
T&O flywheels, go for 84 inch, why not, also benefit from better squish. Do have to mill the heads for slight popup.
Harley rods, just pay the price, everything else is lots of work, see prev. post.
Wait for the repop cylinders from Enfield racing, they're under re-engineering right now. Saw a preproduction set at Jefferson in Oct.
Repop heads, good luck, try to personally inspect them for faults in casting.
Use the vtwin pistons, good quality.
Do something about the oiling system, the gyro pump has been getting good reviews here.
The repop valves seem o.k., go to American cycle fab for springs, typical repops are a little weak.
Use H-D tappets and bodies, they're out there at all the swap meets.
Vtwin drive side main bearing kits work fine.
Vtwin pinion side bearing retainers don't fit properly, However, if you grind down the ones made for the drive side to the same dimensions, they will work fine.
Good luck on cams, Haven't tried repops yet, and originals are getting more and more expensive.
That's the major pieces, lots of odds and ends to come up with, but they're out there.
I go to the major AMCA meets in my area and can usually come up with everything as I need it.
I've been building a project bike a year since I retired, Bobbers basically, and several have been BTSV's.
All from scratch, finding parts on ebay or the meets. I start with a Vtwin repop frame and a DNA springer.
As I said, not stock.
Image
Image
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knucklebolt

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Location: Six miles East of Cheney, Wa.

Post Fri Nov 28, 2014 9:56 pm

Re: Building a Big Twin Flattie from Bare Cases

That is so nice. Wish I could see more old iron on the road. This summer I saw no old bikes on the road when riding mine, or in fact when out in the car, truck or bug either. That is one fine bike. Do you still own that, or do you build to sell? I'd never be able to let one like that go.

k.
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Frankenstein

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Post Sat Nov 29, 2014 4:12 am

Re: Building a Big Twin Flattie from Bare Cases

No, I don't still own it, I sell them. This one went to England. I had thought this would be a way to enjoy my hobby and make a little loot to boot, which I do, but the net result of my efforts is probably a dollar an hour :lol:
I does give me a good excuse to ride to the meets and dig through piles of parts in search of "goodies". And I really enjoy fabricating bikes, I basically do it all from the ground up. The only capability I lack is the Sunnen hone for rod and case bearing work. I have to borrow time on friend's equipment to perform those tasks. I send out the cylinders for boring as well.
Here are the ones I do own:
http://www.freewebs.com/dicky_linn/
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Dusty-Dave

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Joined: Tue Oct 12, 1999 12:01 am

Location: Ojo Caliente,NM,USA

Post Sat Nov 29, 2014 1:09 pm

Re: Building a Big Twin Flattie from Bare Cases

Frankenstein wrote: I send out the cylinders for boring as well.
/

You ought to get setup to bore cylinders as well! It'l keep your blood pressure down where it belongs. After the last time I took home parts from a machine shop that weren't the size I asked for cause that was just how they always did it and what I wanted didn't matter. I decided to build this fixture.
Image
Works for those oddball things with the valves over the pistons too.
Image
Dusty
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Pa

Site Admin

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Post Sat Nov 29, 2014 2:00 pm

Re: Building a Big Twin Flattie from Bare Cases

Dusty-Dave wrote:
Frankenstein wrote: I send out the cylinders for boring as well.
/

You ought to get setup to bore cylinders as well! It'l keep your blood pressure down where it belongs. After the last time I took home parts from a machine shop that weren't the size I asked for cause that was just how they always did it and what I wanted didn't matter. I decided to build this fixture.
Image
Works for those oddball things with the valves over the pistons too.
Image
Dusty


You always amaze me Dusty. I love your ingenuity. I see your fixture from an I-beam has indicating to bore capabilities built right into it. Just plain awesome !!
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Frankenstein

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Location: Interlaken, NY USA

Post Sun Nov 30, 2014 7:56 am

Re: Building a Big Twin Flattie from Bare Cases

NICE WORK! Where did you find that boring bar? You're right too, you do get tired of people just not "getting it" when you want a specific job done. Of course, now I have no one but myself to blame when things go wrong. :roll:
DD
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Dusty-Dave

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Location: Ojo Caliente,NM,USA

Post Sun Nov 30, 2014 10:27 am

Re: Building a Big Twin Flattie from Bare Cases

Frankenstein wrote:NICE WORK! Where did you find that boring bar? You're right too, you do get tired of people just not "getting it" when you want a specific job done. Of course, now I have no one but myself to blame when things go wrong. :roll:
DD

The bar was in a mill at CMI in the 70s when the program went way wrong and crashed it bad enough to bend the shank. Since it would fit in a lunch box I brought it home and turned the shank down to somewhere around an inch where it was straight with the top. Way fine for my little Atlas Craftsman. At least I don't have to drive a hundred miles to see who messed up the machine work anymore.
Dusty
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knucklebolt

Posts: 330

Joined: Tue Feb 12, 2013 8:27 pm

Location: Six miles East of Cheney, Wa.

Post Mon Dec 01, 2014 9:24 pm

Re: Building a Big Twin Flattie from Bare Cases

I hope the Mad Dogs and Englishmen truly appreciate that bike...

Your other bikes are also bitchen...those are the keepers I assume? I sure have a soft spot for Knuckleheads, after having almost lived on one for so many years. People always seemed to be amazed that It didn't leak...but I never had that problem with it. In fact...there was no problems. However, I began on a flathead, and so it now ends. !!! Full circle.

No AJS? I have a soft spot for AJS, which was my first motorcycle, brought it home in a box(s). By the way, my Knuck was a 1947.

I like the disc brake set ups on the Springers. A Sporter front end was the path of least resistance for me, as I ride just about 99% on the front brake, really only using the rear brake just enough to keep it warm, and almost never putting my left foot on the ground.

Anyhow, well done!

k.
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MarkBranst

Posts: 349

Joined: Thu Jun 24, 2004 12:01 am

Location: Champaign-Urbana, IL

Post Thu Dec 04, 2014 9:29 am

Re: Building a Big Twin Flattie from Bare Cases

Thanks to everybody for the comments and information ... especially Frankenstein (Dick).

Mark
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Frankenstein

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Post Fri Dec 05, 2014 9:27 am

Re: Building a Big Twin Flattie from Bare Cases

Thanks for the complements on my fleet, KB. I was always a BSA singles man, although the AJ's are also handsome machines.
The Knuck is a '47EL, with 80 BTSV wheels, she toots right along.
I'm kinda, sorta, a home buddy Mark, My parents were Normal graduates, my mom's from Lovington, I went to Rose Hulman in Terre Haute awhile. I still have family out that way.
DD
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Cotten

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Post Sat Dec 06, 2014 9:59 am

Re: Building a Big Twin Flattie from Bare Cases

Dusty!

I've been all through my Machinist's Bedside Reader, and still cannot figure out how you secured the I-beam to the saddle, and how you adjust the height of the cylinder bore true to the lathe's centerline.

Shims?

....Cotten
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Pa

Site Admin

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Location: Ohio USA

Post Sat Dec 06, 2014 11:25 am

Re: Building a Big Twin Flattie from Bare Cases

Cotton....I assumed Dusty adjusts the vertical with the vertical screws he built in and the lateral with the compound.
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Cotten

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Post Sat Dec 06, 2014 12:28 pm

Re: Building a Big Twin Flattie from Bare Cases

Pa!

Although Photobucket isn't friendly to me, I can't see how the assembly could just 'float' on the vertical threaded rods.
They would have to pull down on shims beneath the fixture to be stable enough.

Did you drill and tap your saddle Dusty?
(I've done worse things to my Logan...)

.....Cotten
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