1950? 500cc BSA project

GoldenMotor.com

harry76

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Apr 16, 2011
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and where do you think those lines with the brass nuts go to that are at the bottom of the cover that says BSA? and when asking about that motor its a nonunit or preunit. You also need to find A parts book that has that motor listed so you know what the part numbers mean.


and you HAVE to use the exact thread for the bolts that are in the motor
whitworth threads will NOT be the same as metric or sae same with british standard threads they are not the same as whitworth threads
YES i knew they were oil lines, but i didnt realise i needed a seperate oil tank, thanks for pointing that out. Like i said ill build one where the tool box goes on boardtracker style bikes. Like i said im no expert on these engines but willing to take any constructive criticism or advice.

The Ebay seller where i bought my workshop manual also sells parts books, would you advise i get that also..... i realise ive taken on more then what i already know, but i thought thats the whole idea of our hobby, learn as you go. I dont know a lot, but after my Villiers build i know a lot more then i did. I dont see this project being any different. Just solving a problem at a time and you eventually get there.

Im sorry but i dont understand the nonunit and preunit reference.

And yes its been raised that the fasteners need to be whitworth, i had the same problem with my Villiers build when i needed to get a whitworth thread turned into my drive pulley.
 

harry76

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Apr 16, 2011
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Thanks for the help, I realize the tranny was seperate, that's the main reason I bought it so I can run a seperate Albion tranny with open primary chain. I think the seperate tranny help pull off the old boardtrack look, more so then something like a Lifan engine with gearbox and tranny in one unit

I'll buy the parts book and check out your link.
 

harry76

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Apr 16, 2011
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Brisbane, Australia
With this build do you guys think I should:

A. Tear down the motor for inspection, and if I have the engine apart and put it back together I may as well paint and polish the engine before I start my frame..... Pros are I'd know my engine was usable before building a frame...... Cons are I will have to be very careful with my freshly painted engine right through fabrication and mockup.

B. leave engine as is until I can design and make my own frame..... Pros are I wont damage my painted and polished engine, and I will Probably have more to do as I'll be able to work on the frame or engine...... Cons are if for some reason this engine is unusable I'll have wasted time and money in a frame.

I'm having a hard time deciding so any advice will be taken on board
 

fasteddy

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Feb 13, 2009
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British Columbia Canada
My first question to myself would be how rare are these engines? If I build the frame first and the engine is clapped to the point that it can't be repaired can I get another engine reasonably even if I have to wait.
Then I'd build the frame.

If not then I'd go through the motor and then build the frame when I was finished the motor clean up and paint and be darned careful to keep the scratches that are sure to happen to as few as possible by wrapping and taping off what I could.

The long way around it to check the motor, put it back together, build the frame and then take the motor apart and clean and paint it up.

As Ibedayank said read about the motor all you can and I'd add join a club that restores these bikes. They are a wealth of knowledge and a source of parts. They may be a little standoffish since you aren't restoring a bike but on the other hand your not trashing one to make a board tracker so a bunch of them may well be willing to help. You will be doing what they would like to do.

Steve.
 

harry76

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Apr 16, 2011
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I often look for stationary engines and vintage motoricycle engines on EBay and ive never seen anything like this, so id imagine it would be hard to replace, at least in my budget it would.

I think ill either pull down and inspect and if nothing looks too bad ill concentrate on the frame or just make a frame and hope. At worst im sure ill find something else to fill the gap in the frame
 

truckd

Well-Known Member
Oct 19, 2010
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palmdale calif
Answer..... # A
Do as much cleaning, repairing,rebuilding as you can and then just be real careful! you could always wrap what you got finished with seran wrap, as I did to protect as much as possible once the engine left the bench, you could even leave certaian parts off during design,fab & mock up like casings,carbs and or anything else that could bump against something else
 

harry76

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Apr 16, 2011
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Brisbane, Australia
I dug out the 21" motocross rim i had in the shed, its brand new. Just with a crappy anodising job, but since i had it sitting around i may as well use it. I sat it next to a 26" bicycle rim i have and there isnt a lot of difference. Avon sell a really nice 21 x 3 if i remember correctly so ill get them, i just need to find another 21" motorcycle rim and hubs to lace them to. Ill run drum front and rear.







I had a lot of yrouble finding steel for my Villiers build, its so dear nowdays sheetmetal shops are hesitant to sell scrap bits...... Well lately i frequent the "trash and treasure" which is a local refuge yard (dump) and they open trash and treasure friday morning and sell all the cool stuff people have dumped. Its pretty amazing whats there, when it opens its on for young and old..... anyways ive found steel a couple of times and its totalled about $12 which is pretty cool seeing as one place wanted $50 for a little bit and i nearly choked before declining their offer. I have enough sheet steel now for at least a few more bike builds.

 

Lurker

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Jan 29, 2010
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Pittsburgh
I'm liking where this is headed Harry. I had no idea a 21" rim was similar in size. I will keep this in mind if I ever do another build.
 

harry76

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Apr 16, 2011
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Brisbane, Australia
I'm liking where this is headed Harry. I had no idea a 21" rim was similar in size. I will keep this in mind if I ever do another build.
To be honest i didnt realise that either, i must thank Mr. B for pointing that out to me, and seeing as a worksman rim would be so dear over here in OZ its saved me a lot of money and will be peace of mind...... I wish someone had pointed this out to you because your bike probably would have benefitted from motorcycle rims perhaps?

Here is the tyre i was referring to, its an Avon 300-21, and it says it ends up with a diametre of 27.21 inches and its really nice looking tyre and very similar to tyres used on boardtrackers

http://www.antiquetyres.com.au/21300

Here are the tyres mounted on a rim and they look badass, im still yet to get a price but if i can get another 21"rim cheaply ill be able to justify these tyres.

http://www.google.com.au/imgres?q=a...0&tbnw=173&start=0&ndsp=24&ved=1t:429,r:6,s:0

http://www.google.com.au/imgres?q=a...0&tbnw=172&start=0&ndsp=24&ved=1t:429,r:7,s:0
 

axelkloehn

New Member
Sep 22, 2011
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Germany
I have heard they measure newer motorcycle tires diameter from inside the tires, and bicycle tires and very old motorcycle tires diameter are measured outside, that makes up to a 4" difference sometimes.
You can use Honda XL 23" frontwheels which are pretty close to the 27-28" classic motorcycle look, but I have never tried if classic tires like Avon, Continental or Cooker fit cause they are too expansive
 

harry76

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Apr 16, 2011
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Brisbane, Australia
Are you saying you aren't sure if the Avon will fit my late model motocross 21" rim?

I'll see if I can find a bead size on the Avon tyre, I haven't got a quote yet but from prices on EBay in England I'm guessing $150 a tyre. If they fit they would be well worth the money. Especially if I can get some cheap hubs, and I don't have much invested yet.

I actually looked on EBay for XL rims or omplete wheels, or cheap complete motorcycles but it's slim pickings here. I'm planning a trip to the motorcycle wreckers for hubs or wheels and have a look for a steering tube.

Mr B, you have a vintage 21" rim don't you? Could you please measure the bead size to compare it to my motocross rim?
 
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harry76

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Apr 16, 2011
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Brisbane, Australia
I want as large a wheel as possible. I already have one 21" rim, I'll find another, I have a feeling my friend has one he'd sell cheaply. And all I need to do is find a couple of hubs and lace them up.

While i appreciate the offer to have anything sent from the States usually makes it too expensive. I'll definitely try to source items locally or from England which is roughly half the cost of postage, which for complete wheels could be hundreds of dollars..... And im doing this build on a tight budget with hopefully all the work done by me
 

Mr.B.

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Oct 21, 2008
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Upper Mississippi River valley
Could you please measure the bead size to compare it to my motocross rim?

Modern 21” motorcycle tires =
(including vintage motorcross)

21” inside tire diameter.
22” outside diameter of rim.

Appox 27” outside of tire diameter depending on the tire.

----------------------
26 x2.125 Bicycle wheels =

21.75 inside tire diameter depending on the tire.
22.5” outside diameter of rim.

Appox 26” outside tire diameter depending on the tire.

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28 x 2.5 Antique motorcycle wheels (aka: tall wheels or skinny wheels)=

24.75” inside tire diameter depending on the tire.
25.1” appox outside diameter of rim.

Appox 28” outside tire diameter depending on the tire.

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Keep in mind most vintage fat tire & modern bicycle frames are about 10% smaller than the actual early motorcycles were.

Not having the properly proportioned wheels is pretty noticeable in my opinion.

Axelkloehn,

I not familiar with XL 23” Honda wheels, but they sound intriguing if they’re close in size to the early tall wheels.

-Kirk
 
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harry76

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Apr 16, 2011
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Brisbane, Australia
Thanks so much Mr B, invaluable info you have supplied me there. I don't feel like paying a fortune on tyres so I may just go with my 21" motorcycle rims...... But I may do a little more digging into the 23"XL rims but I think they would be a hard find. Thanks again

I'd love to get the proportions exactly right (and from having interests in cars I realize how much 1" in a wheelsize can make a massive visual difference, but budget will probably make my decision for me. I've seen the 21" motorcycle rims used on a boardtracker and although not perfect still looked good enough
 

harry76

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Apr 16, 2011
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Brisbane, Australia
Ive had a decent search on the 23" Honda rim and i did find a complete wheel for sale, but then i tried to search for a tyre to fit and i couldnt find any (obviously there are tyres available), and i definitely didnt see any tyres i liked