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1966 Bsa 650 on a budget

26K views 214 replies 20 participants last post by  MikeJustice55 
#1 ·
I picked up a 1966 bsa roller with complete engine for $450 at a swap meet about 8 years ago, lost interest and gave it to my dad then decided to build something again so i got it back from him. Heres the plan.... do as much work as possible solo and reuse as many parts as possible to keep this thing CHEAP. I work at a machine shop so i will be making what I can and have good painting skills so we will see how this goes.
 
#36 ·
Ok ill look into getting some threebond. What kind of rod bearing clearence should i look for with these motors? Should i still follow the .001 per inch journal size so i would be looking for about .0016-.0020? Or does bsa have a different clearance spec. I couldn't find this info in my workshop manual.
 
#41 · (Edited)
I drew some oil passage ways on your pic.

Yellow lines are drilled passages.

You can see the rear feed fitting entering the head and leading to the center boss for the intake rocker arm. That boss is drilled downward into that passage so that oil can reach the rocker arm. The top is then plugged.

The side drilling is to connect the intake rocker arm feed to the exhaust rocker arm feed. It is drilled from the from the front then plugged.

The oil makes it from the center boss to side boss (and up to the front) through the rocker arm (in purple).

Jason

 
#42 ·
Had a productive day at work today. That means it was good for me and bad for my boss. I got the crank float dialed in to about .0024 after 5 shimming attempts. Honed my jug and found a little damage in the lifter valley i need to clean up. Removed all my valves and spun them in the lathe to make sure none were bent. Then lots of cleaning. Ill finish lapping the valves and check rod bearing clearance tomorrow.
 

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#43 ·
Plastiguaged out almost right at .002. With the better oil we have these days im confident everything should work just fine on the lower end. A lot of people skip this step but this gives me peace of mind that i didnt remove too much material when polishing the journals. Also bsa rod end nuts are absolute garbage. I will be using different nuts for final torque ill assemble the cases and lower end at home over the weekend. The shop is just too dirty for me to do assembly. Hand Fluid Finger Gas Thumb
 

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#47 ·
They aren't really necessary...out of the dozens of BSA twins I've worked on, only two still had them. Pack the lifters with grease, or temporarily slip a small O ring over each one and they ought to stay in place when fitting the cylinders.
 
#49 ·
So the frame had some damage on the back half like it was tweaked a bit, maybe a low speed wreck or something so this make the frame a good option for a custom frame i have been wanting to try. Im going to do a softail design with a monoshock to the backbone of the frame to the rear suspension. Heres a little sketch of the idea. If i doesnt work out ill go rigid hardtail.
 

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#50 ·
The frames on these things are made of some pretty substantial stuff, so it should be able to handle the forces encountered with a monoshock set-up. If you can get your pivot bushing mounts up near the location for the swing arm pivot, it ought to work well (too low and it will play nasty games with your chain tension). You seem to be a pretty clever guy, so now that you've cut the rear end off, I say go for it! :D
 
#51 ·
Haha thanks Goldy. Im going to give it a shot. I was thinking about trying a spring loaded chain tensioner to absorb any slack so i could make the pivot point a little lower for a cleaner look but we will see how it goes. I ordered a 900lb monoshock for $60 so when that shows up i can start doing some fab work.
 
#56 ·
Finished up the lower swing arm mounts today. Now i need to mock up the stance to figure out how long and how much of a drop to make the swing arm. And i need my monoshock to be able to half ass assemble this thing. Really hoping i dont have to end up cutting this stuff off later to do a rigid.
 

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#58 ·
Quietly following this in a jealous sort of way, looking good. Just going back to your sketch, you wrote ‘brass bushes’. These should be bronze, not brass. I can’t tell from the pics, but to be honest I can’t always tell when I’m holding the material in my hands. Chips come off brass when turned, wigglies come off bronze.
 
#59 ·
Quietly following this in a jealous sort of way, looking good. Just going back to your sketch, you wrote 'brass bushes'. These should be bronze, not brass. I can't tell from the pics, but to be honest I can't always tell when I'm holding the material in my hands. Chips come off brass when turned, wigglies come off bronze.
We call them brass bushings at work but they are actually oil lite, oil impregnated bushing material. When you press them in they will actually drip oil out of them. Its also important not to weld the boss with them already installed as well because it will cook the oil out and ruin your welds. (I learned to run the lathe with this material because it cuts smooth and easy at most normal speeds and feed rates)
 
#61 ·
Alright, so this is starting to come along, i think i need to get a rear tire to be able to actually figure out where i want to weld my axle plate. Also after mounting the shock i need to try to move it forward at least 1.5 inches to be able to fit a tire without putting a ridiculous stretch on the rear.(so ill be cutting off the work i did today) I dont exactly want it to look like a dragster or a hillclimber with a 4ft swing arm. We gotta keep it looking like a restomod with a little class.
 

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#62 ·
In photo #2, showing your top run of tubes in the foreground: Might you have the (shock, etc.) clearance to make the bend earlier? I mean the bend where the tubes converge on the downtube. The bends in the pic look about like Triumph's factory angles, and those stick out awkwardly when you mount a seat with a skinnier front -- as you might want to do.

I don't know if I'm being even slightly clear. I mean: think about giving your rear top tubes a 30° bend, beginning farther toward the bike's rear, instead of the roughly 45° bend they appear to have now.

Whew.
 
#64 ·
Ah, i see what you mean with that ill have to mock it up to see whats going to happen with the seat issue. I want to mount the back side of the shock before the bend so the bend in the tubes will be more for looks and nice lines. It may be too tight of a bend as youre saying though. I wont know untill i get it set up.
 
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