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educate me #783450 09/04/19 5:47 pm
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scott garland Offline OP
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I have been riding bikes for about fifty years so I know a little. The English bikes include 58 BSA Gold Star Catalina, BSA A10 and a BSA A65 1970 year model. Triumph 1955 Speed Twin, 1955 Thunderbird and a 1968 TR6. No Norton of any model. My question is and I don't want to start a war, is what are the pros and cons of the unit construction models of BSA and Triumph. I am looking for a project English 40 cubic inch bike. I am a conservative rider and rarely run at the 90 and up area. Just want to build a good oil tight keeper.

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Re: educate me [Re: scott garland] #783452 09/04/19 6:19 pm
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A lot of pre-units have worn mounting holes now.

In fact they had fifty years ago!


Amateur Loctite enthusiast.
Re: educate me [Re: scott garland] #783455 09/04/19 7:32 pm
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Originally Posted by scott garland
I have been riding bikes for about fifty years so I know a little. The English bikes include 58 BSA Gold Star Catalina, BSA A10 and a BSA A65 1970 year model. Triumph 1955 Speed Twin, 1955 Thunderbird and a 1968 TR6. No Norton of any model. My question is and I don't want to start a war, is what are the pros and cons of the unit construction models of BSA and Triumph. I am looking for a project English 40 cubic inch bike. I am a conservative rider and rarely run at the 90 and up area. Just want to build a good oil tight keeper.


You have owned a 1970 A65 and a 68 TR6 and asking for pro's and con's of unit construction BSA/Triumph ?


"Back in the garage with my [***] detector
Carbon monoxide making sure it's effective...
----THE CLASH-----

Re: educate me [Re: scott garland] #783562 09/06/19 12:49 am
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...all here we know the answer, no matter in which "band" they are but try something different and rebuild a Norton and forget about wars.

Re: educate me [Re: scott garland] #783585 09/06/19 5:47 am
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Originally Posted by scott garland
I what are the pros and cons of the unit construction models of BSA and Triumph. I am looking for a project English 40 cubic inch bike. I am a conservative rider and rarely run at the 90 and up area. Just want to build a good oil tight keeper.

Pre OIF, the handling of the BSA is reputed to be better. Both mine are OIF, so I cannot comment on that.
BSA pros: push rod tunnels are part of the cylinder casting= no push rod tube leaks.
The gearbox is a 'cassette' design, the entire box contents can be removed when the engine cases need to be split.
Only one camshaft, definitely less noise from the timing side.
The kick-start lever hangs down below where it rubs on your leg while riding.
BSA cons: At least one set of push rods are too damn long.
You must remove the entire gearbox, and strip the primary, just to replace any single part in the gearbox. And, you must remove the entire timing cover to get to the gearbox.
The kick-start return spring is a PITA to put back on.
The life of the engine depends largely on the fit of one bushing on the timing side of the crank. This must be ground to a clearance of 0.0015" in line with the crank. Rebuilding these engines requires precision machining by someone familiar with these engines, and such people are rare and expensive today.
Ratio of second and third gears leaves a big space between the two.

Triumph pros: Better parts availability.
The gearbox is behind a separate cover, and single parts can be replaced without the need to take the whole thing out. Primary only needs stripping to replace the main-shaft high gear.
Engaging dogs on the gears are more robust.
Available as, or convertible to, a five speed. Better spaced ratios even as a four speed.
Better oiling system with proper bearings on each end of the crank.
Less expert machine work required to rebuild.
Triumph cons: Push rod tubes can leak if care is not taken to check seal crush on assembly.
Gearbox must be disassembled any time the engine cases are separated. They don't stay nicely assembled to the end cover as with BSA.

If you find each with a well built engine, it's all matter of personal choice. The BSA engine revs a little freer and can run smoother if properly balanced.
However, if starting from scratch, the Triumph engine is easier to build and parts are more available.


Stepping on others doesn't make you stand tall.

71 A65L "Zelda"
92 BMW K100rs "Gustav"
72 T120V cafe project "Mr. Jim"
72 T150V "Wotan"
Re: educate me [Re: scott garland] #783613 09/06/19 3:54 pm
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scott garland Offline OP
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Thanks everyone for their views. The Norton suggestion by reverb is a challenging idea. I think I may give it a strong look.

Re: educate me [Re: scott garland] #783616 09/06/19 5:30 pm
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...I can add to that list:
Triumphs are faster in all the engines due to you actually can tune to different ranges with those 2 camshafts.
Triumph are way nice looking.
Triumph finishes and proportions are better.
Triumph have more information availability to rebuild the engines or to tune some aspects.
Triumph have aftermarket parts and kits available to tune some engines to race etc.
Triumph gearbox are bullet proof in daily riding at strong speed no matter if they are worn out like my 48 500.
I mentioned that the proportions are better? Look the BSA mudguards regarding tyre distance, for example.

Re: educate me [Re: scott garland] #783618 09/06/19 5:51 pm
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"Power egg" vs iconic style.

Edit: someone else's opinion https://www.bsaocsc.org/images/Triumph_or_BSA_Unit_650_Twins_4.pdf pdf

Last edited by Dibnah; 09/06/19 5:54 pm.
Re: educate me [Re: scott garland] #783633 09/06/19 11:11 pm
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Both the BSA and Triumph unit construction 650s changed quite a bit over the years, and then there were the single and twin carb variants of each in most years.
The big change was the oil-bearing frame introduced in 1971, which changed the feel quite a lot, so that's a big factor.

If you don't want to restrict yourself to 650s, there is always the Triumph T140, which is a very nice machine with excellent parts availability and the advantage of disc brakes. Or you could branch out to a Norton as reverb suggested.

If they're put together properly, they're all excellent machines and lots of fun.

Re: educate me [Re: triton thrasher] #783641 09/07/19 12:38 am
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Originally Posted by triton thrasher
A lot of pre-units have worn mounting holes now.

In fact they had fifty years ago!


don't say it don't say it don't say it

aaaaaggghhh

so does my lovely wife.


every day you do not take a chance is a day of your life that you will never get back.
Re: educate me [Re: kevin roberts] #783643 09/07/19 1:38 am
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Originally Posted by kevin roberts
Originally Posted by triton thrasher
A lot of pre-units have worn mounting holes now.

In fact they had fifty years ago!


don't say it don't say it don't say it

aaaaaggghhh

so does my lovely wife.


"so does my lovely wife", hee hee .... Oh, honey, I didn't see you behind me, just on Britbike telling about my race bike and how it blew up, talking with the guys, you know how it is ... baby please put that frying pan down OUCH DON'T do that, I wasn't doin' nothin', now sugar look out with that gun, that's BUCKSHOT woman, BUCKshot, gimme three steps toward the door ....

Lannis (I come close one time)


Play stupid games ... Win stupid prizes!
Re: educate me [Re: scott garland] #783655 09/07/19 3:41 am
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reverb Online Content
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...hey Lannis, with this politically correctness women stuff in most parts of the World, that is very dangerous and no doubt that now impossible to do that type or less offense the other way around.

Re: educate me [Re: scott garland] #783658 09/07/19 4:21 am
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O n the subject,....... As a keeper, I'd elect a Triumph '67 - '70, .......... And notice my shirt!


Down to 1 BSA, 2 Triumphs, 1 '56 Chevy
1 '65 XLCH on the way to Japan!
Re: educate me [Re: reverb] #783712 09/07/19 7:11 pm
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Originally Posted by reverb
...hey Lannis, with this politically correctness women stuff in most parts of the World, that is very dangerous and no doubt that now impossible to do that type or less offense the other way around.


I scratch grass upon steaming piles of "political correctness"! I am an equal-opportunity offender.

Lannis


Play stupid games ... Win stupid prizes!
Re: educate me [Re: scott garland] #783882 09/09/19 10:41 pm
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69 bonney is the sexiest bike in the garage and the a65 may be faster. But if I have to go somewhere it's one of the Norton's, no question.


Rich (last remaining member ThreeMustGetBeers)
"It's not always about going fast. Sometimes it's nice to slow down" (Wendy E.2016)

69 bonney
72 commando
75 commando interstate
06 Suzu..Suzu.. uh appliance
couple of beesas a ducati
and the Snake Bike
and a Honda?
Re: educate me [Re: Richrd] #783894 09/10/19 4:54 am
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scott garland Offline OP
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and the reason is?

Re: educate me [Re: kevin roberts] #783896 09/10/19 6:03 am
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Originally Posted by kevin roberts


don't say it don't say it don't say it

aaaaaggghhh

so does my lovely wife.



Nah, she’s fine. Heehee!


Amateur Loctite enthusiast.
Re: educate me [Re: scott garland] #783898 09/10/19 6:06 am
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I just wanna know....did she have it 50 years ago?

Re: educate me [Re: scott garland] #783906 09/10/19 12:17 pm
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A bit of slop can ease fitment.

Re: educate me [Re: scott garland] #783907 09/10/19 12:26 pm
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norton are by far the most comfortable bikes for the long ride, with the most relaxed motors and highest performance of the three. 500 mile days are a piece of cake and I've done over a thousand a couple times. 1100 miles is normally a day and a half.

Bsa's and Triumph are nice and can be great fun and I need to own both, but the pulling power of the Norton is great. In the twisties just leave it in third and roll the corners and power out while the others are stirring the gear box, making it easy to ride fast.


Rich (last remaining member ThreeMustGetBeers)
"It's not always about going fast. Sometimes it's nice to slow down" (Wendy E.2016)

69 bonney
72 commando
75 commando interstate
06 Suzu..Suzu.. uh appliance
couple of beesas a ducati
and the Snake Bike
and a Honda?
Re: educate me [Re: Richrd] #784489 09/16/19 5:53 pm
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scott garland Offline OP
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If the Norton is that good why then is the Triton preferred?

Re: educate me [Re: scott garland] #784492 09/16/19 6:03 pm
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Originally Posted by scott garland
If the Norton is that good why then is the Triton preferred?



It’s not preferred by everyone.


Amateur Loctite enthusiast.
Re: educate me [Re: scott garland] #784840 09/20/19 1:27 pm
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triton is a completely different bike from the commando. different uses. tritons generally (depending on the motor) handle better in tight turns, but vibrate more.

Commandos are more comfortable, less vibration, and more pulling power. the triumph motor was not used because it was better, but because it was more plentiful.


Rich (last remaining member ThreeMustGetBeers)
"It's not always about going fast. Sometimes it's nice to slow down" (Wendy E.2016)

69 bonney
72 commando
75 commando interstate
06 Suzu..Suzu.. uh appliance
couple of beesas a ducati
and the Snake Bike
and a Honda?

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