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Mr Mike Offline OP
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The comparison of the two bikes is just tempting. Both long stroke singles and 500 cc, one is unit construction, the other is not. The GS carries a bit more weight. Even BSA ignominiously named the B50 "Goldstar" probably in an attempt to revive a brand that was its death throes. I changed my GB sprocket from 17 to 18 to keep the buzz down to reasonable levels so I am not stock. I missed my chance at a GS many moons ago so I have to be content with the only bike I have left. I never understood why an updated Goldie was not the first in the lineup for BSA when they went unit construction.

Mr Mike

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Revised info on gearing, top gear ratio of 5.28, top speed 102 mph and for 4.75 118 mph 7000

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Will Gold Star rev to 7000 on 4.75 ratio?
I revved my A65 to 7000 and further in second and third, but never found long enough and empty road to squeeze 7000 out of her on top gear.

Last edited by Adam M.; 04/12/20 2:40 pm.
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Adam, you are right but i did say not without help but it will pull 6,500 in top on on a straight road which in the UK we have many. I think it was BsaGuy who said a Goldie could not do 100 mph then what about a DB 350 which has been road tested at 105 mph.

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Portland International Raceway has a straight away almost one mile long and I had my DBD geared to redline in top gear just towards the end of it. Can't remember the gearing exactly but I remember the math with favorable conditions of a top speed of 118 mph.


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Originally Posted by John Alexander
I think it was BsaGuy who said a Goldie could not do 100 mph then what about a DB 350 which has been road tested at 105 mph.
I think he said he wouldn't do 100 mph on it.

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A maximum of 100mph is about right for a DB 350, regardless of gearing. A reasonable one made 32hp on a good day. A T100 Triumph made (according to Triumph) 32hp and the Thunderbird cranked out 34. Both the Triumphs were good for about 100mph. The T110 (early iron head) was supposedly good for 42hp, the press demonstrator of which produced 114mph (what is now known is that the bike was anything but standard for that test).

Many years ago, Cycle magazine (I seem to recall) published a 'nomogram' (a time of chart really), where you could input any two of three variable (being hp, drag coefficient and top speed) and find an approximation of the third. A list of drag coefficients was also supplied. Guess what? For a street bike, unfaired, you needed 33hp to do 100mph. Lost the nomogram article years ago, but wish I still had it! Other examples were similarly accurate.

So 105mph on a 350 (I bet the bike was a 'good' one, selected for the road test - had it been a Clubmans TT winner - they were often tested post-race - in which case the motor might have been 'made available' to the promising rider) and 120 on a 500 either indicates a very good engine (and there were period examples of 48hp 500's and 37hp 350's) or a 'spring-loaded' speedo. Other opinions are also valid.

For comparison, the '67 500 Production TT-winning Velo Thruxton (also a slightly modified frame and a very-much less than stock engine, with a 'squish' head and 47hp) was good for 121mph with fairing, timed at the TT.

KW

Last edited by Kerry W; 04/13/20 5:22 am.

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Thanks for all the good input on these big singles. I have had a B25 and a couple of 441's. They seemed to be approaching their limits at about 75-80mph where my B50 with a ported head, 32mm carb and free exhaust does not seem to be at it's limits. I have never ridden I faster than75-80mph but the b50 does have plenty of giddy-up for passing on country roads in the 55mph range. Who would have ever thought that we would be dissecting the gearing and speed potential of these 50-60 year old bikes.

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I think that sums it up perfectly Mike. While I have ridden my GS wide open in the past these days I am more interested in preserving the old girl (and myself) and try to ride it like a perfect gentleman. My A-65's are another matter. The only time they are ridden is in extreme anger.
Still. These days when most of us are sitting around waiting to get out, it is fun to ramble a bit. PRT

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Having ridden both 500 Goldie (Actually a converted B31 but it is a Goldie in all but numbers) and B50. The Goldie feels more "planted" handling wise, probably mainly down to longer wheelbase and weight. The Goldie also vibrates less, this is probably due to the heavier engine and frame.
Would I have a B50? probably yes but I would modify it. Fill the ends of the bars with lead to help dampen the vibes, electric start would make it more town friendly


BSA B31 500 "Stargazer"
Greeves 200 "Blue Meanie"
Greeves 350
Greeves 360
Suzuki GSX1100 EFE "Sorcerers Apprentice"
GM500 sprint/LSR bike "Deofol"
Jawa 500 "Llareggub"
Aprilia RSV Mille "Lo Stregone"
'35 & '36 OK Supreme
Kawasaki ZZR1400 "Kuro no senshi"
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Goldstar 500 bore 85, stroke 88
B50 bore 84, stroke 90.
Surprising , given the trend for more over square motors as time goes on.

On paper the goldie is less under square and should rev higher than a B50.
I havent ridden a stock B50, I have ridden a couple of Goldie variants, agree with the handling comments.
The much shorter motor unit of the B50 allows for a significant wheel base reduction, a friend stuck one in a featherbed frame , chopped 6 inches out of the frame rails , a 50 inch wheel base, twitchy.
A lighter bike with a longer stroke is going to feel ruffer. The long wheel base high mass goldie with a shorter stroke will be "smoother" than a B50 , as a massive generalisation.


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56 Norbsa 68 Longstroke A65
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Stock B50 MX motor- Can't say what the primary gearing is, with 19-49 final will take the bike beyond 6000 rpm on a long straight at the track. I won't hold it there and let off before bad things happen. The bike is a bit lighter than from the factory. I'm probably 170 lbs with gear on. The bike has shown 26hp on the dyno at the rear wheel. I've not ridden a goldstar so can't compare but the B50 feels solid in turns and on long straight. More fun to ride than the 650 for sure.

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Another thing that helps with the smoothness of my "Goldie" is the Pearson crank. This is a proper pressed up crank instead of the BSA short taper and nuts arrangement which flexes and flaps around


BSA B31 500 "Stargazer"
Greeves 200 "Blue Meanie"
Greeves 350
Greeves 360
Suzuki GSX1100 EFE "Sorcerers Apprentice"
GM500 sprint/LSR bike "Deofol"
Jawa 500 "Llareggub"
Aprilia RSV Mille "Lo Stregone"
'35 & '36 OK Supreme
Kawasaki ZZR1400 "Kuro no senshi"
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How is the Pearson crank different and why is it better than taper fit and nuts?


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The Pearson crank has the crankpin pressed into the full thickness of the flywheels. This means the crankpin is much better supported than the tapers that only go about half way into the flywheels
The mainshafts are also pressed in the full thickness as opposed to the BSA method of a flange with rivets that are prone to becoming loose


BSA B31 500 "Stargazer"
Greeves 200 "Blue Meanie"
Greeves 350
Greeves 360
Suzuki GSX1100 EFE "Sorcerers Apprentice"
GM500 sprint/LSR bike "Deofol"
Jawa 500 "Llareggub"
Aprilia RSV Mille "Lo Stregone"
'35 & '36 OK Supreme
Kawasaki ZZR1400 "Kuro no senshi"
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The Pearson flywheel material is probably also a better spec than the original flywheels.

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It's not just engineering, it's aesthetics. Looking at them side-by-side, the Pearson crank is a thing of great beauty. So much so that I almost regret installing it.

The original BSA crank has a rugged look that betrays its 'Peaky Blinders' origins.

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I haven't ever seen an original DBD crankshaft, but here is a B44 crankshaft ready for reassembly with new oversize rollers (supplied by Ed Valiket after honing the rod). B50 is similar except for needle bearings. I thought that a proper taper fit was superior to simple press fit. In any case, I guess I need to see a Pearson crank for comparison.
2nd photo is B40 crankshaft with similar bearings to B44 but with straight pressed in crankpin.

[Linked Image from i.postimg.cc]

[Linked Image from i.postimg.cc]

Tom

Last edited by koncretekid; 04/18/20 12:46 am.

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This is the Pearson crank inside mine
[Linked Image from live.staticflickr.com]20150926_113209_zpsmdaxplgu by Sigma Projects, on Flickr


BSA B31 500 "Stargazer"
Greeves 200 "Blue Meanie"
Greeves 350
Greeves 360
Suzuki GSX1100 EFE "Sorcerers Apprentice"
GM500 sprint/LSR bike "Deofol"
Jawa 500 "Llareggub"
Aprilia RSV Mille "Lo Stregone"
'35 & '36 OK Supreme
Kawasaki ZZR1400 "Kuro no senshi"
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Some good stuff here guys. I was just looking back thru some old files I had and I came across the procedure I had concocted for starting a B50. This came out of necessity. One time I was riding to a vintage race event with some other guys and we had to stop for gas. Well my B50 would not start and after an embarrassing 5 minutes I told the other guys to go on ahead. I finally got the beast started and rode by myself to the event but decided that I was gonna figure out how to start this beast or someone else was going to own it. That winter I spent going through the carb and various starting techniques until I came up with what follows. Believe me it works. This spring I started my B50 after about 5 months idle on the very first kick! Here it is:

Starting a BSA B50 (cold)
1. Make sure timing is reasonably close to spot on and the points are correctly gapped.
2. The carb must be clean. Especially important is the idle mixture jet which is cleaned with a #78 drill wedged in a red WD-40 spray tip. It must be absolutely clean! Don't just run some compressed air and carb cleaner through it.
3. The throttle slide stop screw needs to be screwed in about 1/2 to 3/4 turn. This would be a very fast idle when the bike is warmed up. I brazed a knurled post onto the stop screw so I can adjust it with a gloved hand and don’t have to get out a little screwdriver. I also have a knob on the mixture screw.
4. Liberally flood the carb with the tickler.
5. With ignition off, prime the cylinder by kicking over the motor using compression release a couple of times with the throttle open. Reflood the carb with the tickler again.
6. With ignition still off, ease the motor over TDC using the compression relief. Continue tuning the motor over with the kicker until you feel the springiness of the exhaust valve opening. This is about 70 to 80 degrees past TDC. (This is very important!) It helps give the engine more speed as it goes thru intake and then compression and the extra speed helps it got over TDC.
7. Reset the kicker to the top, turn on the ignition and give it a real hard kick. Don’t use the decompressor as you are over TDC. Mine starts like this even when batteryless.

It should start easily. After it warms turn the idle adjustment screw to achieve the desired idle speed.
On a hot start (like after a stall or gas stop), you really only need follow steps 6 and 7. If the bike sits for about 20 minutes follow steps 3, 6 and 7.
Works for me!!! Unfortunately it took me many years of BSA single ownership to figure this out....and despite that twins start much easier, I still stick with my big single. Some say to bump start. This has never worked for me as the rear tire just skids on the pavement when the motor comes up on compression. I had a Starfire 250 in college. I had a nice little hill in my driveway and just was not heavy enough to bump start it. The B25 was no so easy to start either.

Hope someone finds this helpful.

Mr Mike

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Thank You Mike, When you posted this it changed my life. Really. No more fruitless kicking! PRT

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The start procedure for my "Goldie"
1) Turn on fuel
2) Engage cold start
3) Turn on ignition
4) Pull decompressor lever
5) Press red button
6) Release decompressor lever
7) Release red button

For a cold start omit 2


BSA B31 500 "Stargazer"
Greeves 200 "Blue Meanie"
Greeves 350
Greeves 360
Suzuki GSX1100 EFE "Sorcerers Apprentice"
GM500 sprint/LSR bike "Deofol"
Jawa 500 "Llareggub"
Aprilia RSV Mille "Lo Stregone"
'35 & '36 OK Supreme
Kawasaki ZZR1400 "Kuro no senshi"
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As for the flywheel comparison one must consider that the GS shafts are held in by rivets that can work loose. The B44/B50 shafts are much more substantial.

Gordo


The roadside repairs make for the best post ride stories.
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