BSA B50T from Trial to Race bike

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BSA B50T from Trial to Race bike

Post by OrcHero99 » Wed Feb 13, 2019 8:22 am

Hello everybody

I'm from Switzerland and I want to introduce you to my BSA project. The whole thing started with an original BSA B50T 1971. Currently I am on my way to finish it as a racing motorcycle. In the coming weeks, the motorcycle will be tuned on the dyno and then used at various racing events in Switzerland. Only the frame and the crankcase as well the cylinder head could I take over from the original BSA. Everything else has been rebuilt.

I would be interested in your opinion. How do you like it visually? Do you have technical questions? Many problems that are discussed here in the forum, I have effortlessly implemented in my project and much of it has been reinforced.

Best regards
Claudio
BSA B50T Original.JPG
BSA B50T Umbau 1.jpg
BSA B50T Umbau 2.jpg
BSA B50T Umbau 3.jpg

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Re: BSA B50T from Trial to Race bike

Post by JB » Wed Feb 13, 2019 9:22 am

WOW...what an amazing transformation :thumb
Just from the photos it looks like you've done a high quality job... I'm very interested in reading more about this bike and its build.
Cheers John

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Re: BSA B50T from Trial to Race bike

Post by minetymenace » Wed Feb 13, 2019 12:49 pm

<135 to the forum OrcHero99

What have you done to the engine? Do you have a DB31 engine in your attic by any chance?
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Re: BSA B50T from Trial to Race bike

Post by OrcHero99 » Wed Feb 13, 2019 1:21 pm

Thank you very much for your messages. I have a lot of photos of the whole project. If you want to see something special, I may be able to post it.

The engine is very heavily modified. Completely new crankshaft, longer connecting rod, larger bore, mega-cycle camshaft, intake valve 47mm, exhaust valve 40mm, valve angle adapted, rocker arms adapted, combustion chamber optimized, piston self-made, modified anvil plunger, self-ignition, 34mm carburettor self-made, Iridium IW27 spark plug, Nova Racing gearbox, NEB clutch, bleeder valve for jump start ...

I hope you can imagine what I mean.

Best regards

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Re: BSA B50T from Trial to Race bike

Post by koncretekid » Thu Feb 14, 2019 2:51 pm

Very nice looking bike. I would be interested in your combustion chamber modifications as well as rocker arms and valve angles.

I note you do not have a seat in place. A Matchless G50 seat looks nice on a race bike, if you don't have one yet.

My shop has never been that clean!

Tom
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Re: BSA B50T from Trial to Race bike

Post by OrcHero99 » Thu Feb 14, 2019 5:22 pm

Hello Tom

A G50 seat would look good, but I already made my own fiberglass seat. Here are some pictures of this process.
1.jpg
2.jpg
3.jpg
4.jpg
x3.jpg
The rocker arms were severely slimmed down. So that these are as easy as possible. In addition, new adjusting screws and special valve hoppers were used. The combustion chamber was partially welded and then adjusted / reduced. The valve angle was flattened with reasonable effort so that the large valves do not pull too large valve pockets.
IMG_1537.JPG
I could possibly find pictures of the combustion chamber.

Cheers,
Claudio

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Re: BSA B50T from Trial to Race bike

Post by koncretekid » Thu Feb 14, 2019 11:23 pm

Thanks,
I'll be interested to see the results of the dyno testing. The seat looks great.
Tom
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Re: BSA B50T from Trial to Race bike

Post by madsundaysurvivor » Fri Feb 15, 2019 3:49 pm

Great look and very nice exahust!
What about the front drum brake? Is yamy or suzuk?
The rear tyre is the avon that I always used, the front is a hendinau?

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Re: BSA B50T from Trial to Race bike

Post by beat » Fri Feb 15, 2019 10:47 pm

minetymenace wrote:
Wed Feb 13, 2019 12:49 pm
Do you have a DB31 engine in your attic by any chance?
most of them have two ( DB 34 ) in the attic here, - some unlucky ones have only one...

:(

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Re: BSA B50T from Trial to Race bike

Post by OrcHero99 » Mon Feb 18, 2019 8:53 am

koncretekid wrote:
Thu Feb 14, 2019 11:23 pm
Thanks,
I'll be interested to see the results of the dyno testing. The seat looks great.
Tom
Hello Tom

Next week the bike will be pressed on the test bench. I'm curious how the torque develops and where the maximum power is. I will contact you as soon as I have the results digital.
madsundaysurvivor wrote:
Fri Feb 15, 2019 3:49 pm
Great look and very nice exahust!
What about the front drum brake? Is yamy or suzuk?
The rear tyre is the avon that I always used, the front is a hendinau?
Hello madsundaysurvivor

The front brake is a John Tickle double cam drum brake. The rear tire you have correctly recognized, the front is an Avon Roadrider with the soft mixture. The combination of these tires is perfect for my driving style.
beat wrote:
Fri Feb 15, 2019 10:47 pm
minetymenace wrote:
Wed Feb 13, 2019 12:49 pm
Do you have a DB31 engine in your attic by any chance?
most of them have two ( DB 34 ) in the attic here, - some unlucky ones have only one...

:(
:laugh


Best regards
Claudio

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Re: BSA B50T from Trial to Race bike

Post by madsundaysurvivor » Mon Feb 18, 2019 3:44 pm

Thanks OrcHero99.
Yes, I raced with am22 front tire and was very soft (aggresive braking with fontana 4ls), and they had a short live, also used avon f2 striped tyre, but it was quickly stepped

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Re: BSA B50T from Trial to Race bike

Post by OrcHero99 » Mon Feb 25, 2019 8:04 am

Hello everybody

Last weekend, the BSA was strapped to the dyno and set. After several attempts, we have tuned the intake length and perfected the carburetor setting. In the appendix the successful final measurement. I think the pictures speak for themselves. If you have any questions, I am here for you.

Cheers
Claudio
Prüfstand Messung 2.jpg
Prüfstand Messung 1.jpg

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Re: BSA B50T from Trial to Race bike

Post by stew79 » Mon Feb 25, 2019 10:13 pm

hi claudio, thats a great bike with an excellent dyno figure at the end. (not many of them on here) i have many questions, why make your own carb ? and ignition ? squish clearance and % of bore ? comp ratio ? what fuel ? (must be ave-gas or better)
stew

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Re: BSA B50T from Trial to Race bike

Post by koncretekid » Tue Feb 26, 2019 3:13 am

Those are great numbers! What bikes do you have to race against and what tracks will you race at? I think you'll love the torque and handling of your B50. I know my road race B50, which didn't have that kind of horsepower, was faster than I was able to take advantage of. I am better off in a straight line.
Tom
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Re: BSA B50T from Trial to Race bike

Post by OrcHero99 » Tue Feb 26, 2019 9:38 am

stew79 wrote:
Mon Feb 25, 2019 10:13 pm
hi claudio, thats a great bike with an excellent dyno figure at the end. (not many of them on here) i have many questions, why make your own carb ? and ignition ? squish clearance and % of bore ? comp ratio ? what fuel ? (must be ave-gas or better)
stew
Hi Stew

Thank you very much for the compliment.
The initial plan was a Mikuni or Smoothbore Amal 34mm or 36mm. However, I found that the throughput of such a carburetor does not really match what is needed. From a previous project, the CAD drawings for a homemade carburetor already exist, so it could be easily extended. Here is a picture:
1.jpg
The ignition is mounted on the crankshaft and self-excited. The best experience I have with the STK-010 made by Electrexworld. This works perfectly in combination with a Denso Iridium IW27 sparkplug. (Compression Regardless)

The squish clearance is approximately 0.7-0.73mm and the compression is 10.5:1.

In the beginning, the plan was to run the bike with methanol or at least ethanol. In the meantime I have changed to AvGas 100LL because I can refuel cheap at an airfield nearby. In addition, the temperature should not be a problem with this engine design.

I hope to have served you with this informations.

Best regards
Claudio

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Re: BSA B50T from Trial to Race bike

Post by OrcHero99 » Tue Feb 26, 2019 10:08 am

koncretekid wrote:
Tue Feb 26, 2019 3:13 am
Those are great numbers! What bikes do you have to race against and what tracks will you race at? I think you'll love the torque and handling of your B50. I know my road race B50, which didn't have that kind of horsepower, was faster than I was able to take advantage of. I am better off in a straight line.
Tom
Hello Tom

I don't know my "opponents". I assume they depend on the age of the motorcycle (close to 1971). I will participate this season in various events in Switzerland. Next year on the circuit in France or Germany.

Best regards
Claudio

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Re: BSA B50T from Trial to Race bike

Post by stew79 » Tue Feb 26, 2019 10:32 am

whats the max rpm ? the figures on the 2 graphs contradict each other. amazing power with the 2 stroke type ignition !
stew

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Re: BSA B50T from Trial to Race bike

Post by B44Claus » Tue Feb 26, 2019 11:25 am

Hi Claudio,
Congratulations with your excellent looking bike! If it performs as good as it looks you're on a winner😁
A few questions to settle my curiosity:
Bore x stroke of your motor?
Dyno figures - are they rear wheel horse power?

Brgds,
Claus
B44Claus

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Re: BSA B50T from Trial to Race bike

Post by OrcHero99 » Tue Feb 26, 2019 11:41 am

stew79 wrote:
Tue Feb 26, 2019 10:32 am
whats the max rpm ? the figures on the 2 graphs contradict each other. amazing power with the 2 stroke type ignition !
stew
The max rpm of the engine is close to 6500rpm. When I turn the engine higher, the piston speed slowly rises to an area where it becomes dangerous for the piston temperature. I thought a long time about a piston bottom cooling, but then left the whole thing.

The engine speed on the small picture with the exact measurement data is not correct, this is calculated and not measured. The engine speed on the figure with the torque and power curve is correct. The measurement was stopped at 6500.

Claudio

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Re: BSA B50T from Trial to Race bike

Post by OrcHero99 » Tue Feb 26, 2019 12:27 pm

B44Claus wrote:
Tue Feb 26, 2019 11:25 am
Hi Claudio,
Congratulations with your excellent looking bike! If it performs as good as it looks you're on a winner😁
A few questions to settle my curiosity:
Bore x stroke of your motor?
Dyno figures - are they rear wheel horse power?

Brgds,
Claus
Hi Claus

92x88mm (bore x stroke), almost square.

Here a picture with the exact explanation of the depicted data:
Prüfstand Messung .jpg

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Re: BSA B50T from Trial to Race bike

Post by stew79 » Tue Feb 26, 2019 12:29 pm

thought it was a graph from some one else,s bike ! (nearly 9000 rpm !) ignition retard at high speed will lead to overheating (not just the piston) do you no what your actual timing is ? as those electrexworld things are far from ideal
stew

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Re: BSA B50T from Trial to Race bike

Post by OrcHero99 » Tue Feb 26, 2019 12:41 pm

stew79 wrote:
Tue Feb 26, 2019 12:29 pm
thought it was a graph from some one else,s bike ! (nearly 9000 rpm !) ignition retard at high speed will lead to overheating (not just the piston) do you no what your actual timing is ? as those electrexworld things are far from ideal
stew
We set up the motorcycle, inductively measured the engine speed at the ignition cable, mounted the lambda probe and started the measurement. The displayed motor speed is calculated from the parameterized ratio, we have not made this parameterization and is most likely still from an old measurement (other customer).

34 degrees advance are still humane. The pre-ignition was roughly adjusted with the degree disc, later with the strobe lamp. From 3000rpm to 6500rpm, the pre-ignition is constantly 34 degrees. Trust is good, control is better!

Claudio

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Re: BSA B50T from Trial to Race bike

Post by stew79 » Wed Feb 27, 2019 7:02 pm

hi claudio, the advertised advance / ret figures from electrexworld for the stk-010 have come up in several threads on here before. perhaps your one has a more suitable advance ?, but what is the timing at starting or tick over ? the best power i have seen proof of for a b50 is 53 bhp (only 500 cc on av-gas) i think it had a 38mm gardener carb and the timing fixed at full advance (the people i no with racing gold stars all use fixed timing as well, but can only start the bikes on rollers) as your bike is 585cc with some good mods, i think it has a bit more power to give.
stew

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Re: BSA B50T from Trial to Race bike

Post by OrcHero99 » Tue Mar 19, 2019 11:12 am

Hi everybody

Meanwhile, I was again on dyno with the BSA. The pre-ignition is now set as follows and verified with the strobe lamp:

2000rpm = 31°
3000rpm = 32°
4000rpm = 34°
5000rpm = 35°
6000rpm = 35°

With this pre-ignition results a maximum power of 49.5HP at the rear wheel. Maximum 65Nm in 4th gear with a maximum speed of 155km/h at 6300rpm.

Here are some pictures of the finished BSA. I hope the coming season will be successful.
3.jpg
1.jpg
Best regards, Claudio

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Re: BSA B50T from Trial to Race bike

Post by CCM620 » Tue Mar 19, 2019 11:33 am

Beautiful!

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Re: BSA B50T from Trial to Race bike

Post by minetymenace » Tue Mar 19, 2019 12:16 pm

If that goes as well as it looks, podium is guaranteed.
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