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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.
 
#108 ·
Ok...I was trying to keep my big mouth shut, but now I can't. Mike, your tail section looks great and appears to be built with strength in mind, but had you put the pivot point for the tail directly in line and behind the engine sprocket and as close as possible to that sprocket (like the original swingarm pivot point), you might not need a chain tensioning device at all. Having said that, with the engine straining the top run of the chain, I think putting the device on the bottom run is the only way to go, but it will be compressed when engine braking as well, so you will need a really strong spring. On another note, I think teflon is indeed a great choice for the tensioner wheel material. Please don't take these comments the wrong way, I'm trying to be a "helpful arsehole", so keep up the progress, I'm sure this will turn out to be a unique machine. :D
 
#112 ·
Ok...I was trying to keep my big mouth shut, but now I can't. Mike, your tail section looks great and appears to be built with strength in mind, but had you put the pivot point for the tail directly in line and behind the engine sprocket and as close as possible to that sprocket (like the original swingarm pivot point), you might not need a chain tensioning device at all. Having said that, with the engine straining the top run of the chain, I think putting the device on the bottom run is the only way to go, but it will be compressed when engine braking as well, so you will need a really strong spring. On another note, I think teflon is indeed a great choice for the tensioner wheel material. Please don't take these comments the wrong way, I'm trying to be a "helpful arsehole", so keep up the progress, I'm sure this will turn out to be a unique machine.
The pivot point is only about a couple inch or so off from the original swing arm location and with the shock off lifting the rear of the frame it doesnt seem to move the chain much. The tensioner may not be necessary. I might end up with a simple lever style tensioner on the bottom side to just eliminate chain movement. Now the real decision is to try it first or scrap the idea completely. I may drop my motor in and fire it up and rip around a bit before disassembling for paint.
 
#110 ·
Start by having a look at this.
https://www.mcmaster.com/chain-tensioners
You should see that the manufacturers do not make pedestals. Also you will not find single pedestals, there is no substantial resistance to bending or tracking, and there is lot of force involved. Do not assume that because you saw one on line like yours that some garage guy made that it's the way to go. If it was the industrial manufacturers would make them that way.
Now lets get into using spring travel, a spring system will bounce. This will in short order break your pedestal tensioner. Elastomers work best as they self dampen.

Now that it's been mentioned your design with the bottom pivot is bad. A look at any Softail is a good example. Again just because some back yard guy did it doesn't make it the way to go.
Altering your design to put the pivot in or near alignment with the sprockets, would rid you of the need for a tensioner.
Tensioners are not usually on the driven section, unless they are solid and don't actively tension.
 
#111 ·
Start by having a look at this.
https://www.mcmaster.com/chain-tensioners
You should see that the manufacturers do not make pedestals. Also you will not find single pedestals, there is no substantial resistance to bending or tracking, and there is lot of force involved. Do not assume that because you saw one on line like yours that some garage guy made that it's the way to go. If it was the industrial manufacturers would make them that way.
Now lets get into using spring travel, a spring system will bounce. This will in short order break your pedestal tensioner. Elastomers work best as they self dampen.

Now that it's been mentioned your design with the bottom pivot is bad. A look at any Softail is a good example. Again just because some back yard guy did it doesn't make it the way to go.
Altering your design to put the pivot in or near alignment with the sprockets, would rid you of the need for a tensioner.
Tensioners are not usually on the driven section, unless they are solid and don't actively tension.
The ones i have seen were not custom made but they were in fact solid mount tensioners. The plus side is i only have $11 and some time in the current tensioner so its not a big deal to change it. You are probably correct that once it undergoes a lot of stress it may end up bent or broken. I might have to scrap this idea. (Sure looks cool tho)
 
#114 ·
you made a chain guard so put a teflon or whatever bar/slider in there
and a tensioner on the bottom if you need it
i have a dirt bike chain runs on top of swing arm on a slider near the pivot, theres a roller underneath the pivot and another guide near the hub.
 
#116 ·
The rollers on dirt bikes are not tensioners, they are solid mount and guides to keep the chain off the frame and a slider wrapped around the front of the swing arm to protect the swing arm from the chain.
They also are so positioned as to keep some slack out of the chain thru it's range of travel. This positioning is some thing you could try with a solid mount guide.
 
#117 ·
Im going too keep moving forward with it and give it a shot and see what happens. Im confident anything that breaks i can fix. If i need to change it i will likely go with solid mount dirtbike stuff. Its definitely an easy fix if i dont like it anyway. But i want to run this thing before tear down for paint anyway. It may end up a rigid by the time this is all done but im learning a lot with this build and most things are one step forward two steps back.
On a side note, i appreciate any opinions or criticism. It is always good to have someone make me think twice about what im doing. Its nice to hear "hell yeah that looks good" but i wont learn anything from that.
 
#118 ·
Headlight mount and ears I fabbed today. Its 304 stainless because someone bought all of our steel. +1 for colorful welds but i would have rather used steel since they will be painted anyway. Except the brass bits. Those will be taped off and cleared.
 

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#119 ·
Heres a rough roller so far. I wont be using those bars but most everything else is what ill use. Ended up with a trailer leaf spring to mount the seat and it works very well. Also fabbed the license plate mount today
 

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#126 ·
Now i know why these cost as much as they do. This set of brass risers took a total of 3.25 hours. The first pic is the raw materials i got for free from a couple of destroyed air cylinders from a local dairy farm. My buddy at work cut them on the water jet on his lunch break then i machined the rest.
 

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#130 ·
Haha i know i get so excited when i find a piece of brass that will work for something id like to make. Its like finding gold. The brass plates are actuall scrap brass tubes from the dairy farm that i cut and unroll with a lot of heat and a lot of hammering.
 

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#131 ·
Amazing. You wouldn't have more interim pics of the process, would you?

There's a salvage yard in Oakland that used to be a great source of really unusual scrap. Nonferrous metals only, meaning they had, for instance, a 30-foot, multishelf rack stuffed with crushed trombones and saxophones. Lot of brass & bronze takeouts from fine old hotels that had gone bust, et cetera. That was thirty to twenty years ago, now the owners seem to have little patience for customers who don't buy in bulk. Understandable but sad.
 
#133 ·
Im thinking of making a 2 into 1 intake manifold for the engine. Its a dual carb head and i have a single 932 amal off of a single carb bsa. Could i jet this carb up and put the dual fuel feed fitting on the bottom and make a manifold for single carb? Ive done this with old dirt bikes when i was younger and never had any issues. Id rather have one carb to tune and i dont want to buy another carb.
 
#134 ·
I made my 2 into 1 intake manifold and did some silicon bronze brazing on it to add a better look. I have an amal off a single carb 650 triumph im going to try out and see how it runs. I also machined my foot pegs out of brass and knurled them. Ill hopefully make a set of matching grips the same way. The project has slowed down a bit but i plan on getting back on it soon to get it ready for paint.
 

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