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#476377 - 02/10/13 2:13 am Pre-unit T100 with 650 crank shaft questions  
Joined: Apr 2006
Posts: 261
RGSDave Offline
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RGSDave  Offline
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Kansas City
I'm getting ready to start putting parts together for this 1954 T100 engine. I'm not real familiar with 500s, I've mainly dealt with 650s. I know, same but different. I have the stock crankshaft and I have a one piece later pre-unit 650 crankshaft. My main question is with crankshaft and the rods; will the 650 work in the 500 engine without any major issues? The rod journals on both cranks are the same size and I would like to get away from the Babbitt rods of the pre-unit 500. Is it possible to run 650 rods on the 500 crank? If so, do you need to clearance the skirts of the liners? As you will notice from the pictures, the 650 crank has been balanced and the fly wheel on the sides has been shaved down. I'm not proficient in crankshaft balancing. Does the 650 crank look correct? Any advice and input would be greatly appreciated. I really don't want to start throwing money at this and have to do it twice.

Thanks,
Dave














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#476381 - 02/10/13 4:13 am Re: Pre-unit T100 with 650 crank shaft questions [Re: RGSDave]  
Joined: Jul 2009
Posts: 3,549
Pete R - R.I.P. Offline
In Remembrance
Pete R - R.I.P.  Offline
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Posts: 3,549
Vic. Australia
The later rods should work OK on the early crank.The weight could be heavier.71% balance factor seems to be OK on a pre-unit.They were less than that,from new (about 62%).
I don't think you'd have any liner clearance issue,but check it anyway.

The 650 crank has 2 mm more stroke.The pistons will be 1 mm higher at TDC.A shim at the cylinder base could fix that.The thread for the crank pinion is longer.Cut some off,so it clears the timing case bush.

The flywheel on the 650 crank looks wrong.It's had a lot of metal taken off to reduce the balance factor.The balance factor may be too low,even for your pre-unit.
If it still had about 30 or 40 grams more counterweight than the pre-unit crank,it would be about right.

Support the cranks with bearings,and see how much weight you need to hang off one crankpin on a string to get balance.

#476400 - 02/10/13 9:42 am Re: Pre-unit T100 with 650 crank shaft questions [Re: RGSDave]  
Joined: Feb 2011
Posts: 3,352
Boomer Online content
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Boomer  Online Content

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Orygone
I may be wrong as I'm a BSA guy but by '54 wasn't the 500 crank upgraded? Didn't they have rod bearing inserts and also a new timing side mainbearing? Is there a small bulge or "blister" below the timing chest to show the cases use the larger mainbearing?

Bill AKA


Boomer
#476402 - 02/10/13 9:59 am Re: Pre-unit T100 with 650 crank shaft questions [Re: Boomer]  
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Pete R - R.I.P. Offline
In Remembrance
Pete R - R.I.P.  Offline
In Remembrance

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Posts: 3,549
Vic. Australia
The first big crank engines ran the aluminium rod directly on the crankpin.Only the steel cap was white-metalled.Bearing shells weren't fitted.
It might have been a year or two later when they first used replacable bearing shells.

#476426 - 02/10/13 3:24 pm Re: Pre-unit T100 with 650 crank shaft questions [Re: Pete R - R.I.P.]  
Joined: Aug 2001
Posts: 6,662
Jon W. Whitley Online content
Jon W. Whitley  Online Content



Joined: Aug 2001
Posts: 6,662
Vermont
Pete,

Not 100% sure but I don't think he'll have to worry about that since he is using another Pre-Unit crank. Same pinions used in '54 through '62 and if one felt so inclined, he could fit an alternator rotor to the drive side, starting in '54.


Dave,
In '54 same rods were used by both the T100 and the T110 - E3328T whereas the 6T and TR5 both used E3328. I don't know what the T stands for. Maybe beefed up, hence the T. In 1956, all models used the E3606 rods as well as being the first year for for using the big end/shell bearings E3586. Of note, the same cranks used for the 1955 models were used, by part number anyway, for the 1956 models with the introduction of the shell bearings.



Originally Posted By: Pete R
The thread for the crank pinion is longer.Cut some off,so it clears the timing case bush.



Jon W.


1957 6T Thunderbird 650
1971 TR6R Tiger 650
1955 Tiger 100 - Project
1970 BSA A65F 650 - Project

#536362 - 04/03/14 12:02 pm Re: Pre-unit T100 with 650 crank shaft questions [Re: Jon W. Whitley]  
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Pre Unit Offline
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Pre Unit  Offline
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terra Australis
Heres a picture ive flogged from a T100r 1955 thing here .

http://i244.photobucket.com/albums/gg15/rgsdave/P1030754_zpsa029632f.jpg

saying its a Std 54 crank & 9:1 pistons .
-----------------------------------------------------------------
The 55 t100r introduced the Big Bearing Crank / case .
bulge under timing cover. same Brg. L & R . cases .

The balance factor is a consideration . some think 72 %
in your expecting it to go better than new W.F.O. .

The 61 T120 rods wernt as beefy as the later ones ,
but I found perfectly adequate at 8.000 + regularly.
DESPITE others gripeing . Less INIRTIA .
likewise excessive dome in pistons MASKS CHAMBER & impedes combustion . the 9.5 650 pistons are likely the optimum crown
shape . run at 9.75 measured dont hang about .

The 55 100R was redlined at 8.000
A measured 7.25:1 saw this repeatedly .

despite not running the necesary .010 clearances & 40 BTDC Ign.
performance loss Av Gas to Pump gas was discernable.
As was kick back bump starting without retard on pump gas .

Low crown pistons and C.R. measured 10:1 Max with your extra 1 mm throw should be simple enough . Id run a reversed 750 Oil pump . dual 1 1/16 carbs .

#536364 - 04/03/14 12:14 pm Re: Pre-unit T100 with 650 crank shaft questions [Re: RGSDave]  
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Pre Unit Offline
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terra Australis
Id used this type of crank in the 61 t120 ,

http://i.ebayimg.com/00/s/ODk5WDE2MDA=/z/7fkAAOxyjxlTOHHL/$_57.JPG

http://www.ebay.com/itm/1972-Triumph-T120-T-120-T120R-Bonneville-650-650cc-491-crank-/231193069761

Ball races rather than rollers will acomodate the crank bow / flex .
Noahs cousin pre cambered the crank , as per some singles . so theyre straight at full load .
With the bolt up 3 piece type .

Id used titanium bolts in the 3 piece 500 crank .

Will be obvious if the pistons are going to collect the crank , trial assembled .
Basic mathmatics for clearance , if reqd . Fly wheel dia. crank throw . rod centres length .
piston depth from gudgeon .

do symmetrical ( both Sides ) if radiused cut outs in skirt .

Put the CIRCIP GROOVE under the Microscope . dont fit pressed circlips backward .
dont be a clutz and distort / deform circlips by incorrect handling . ( some idiots
think piston rings are difficult . ! )

get Stan Shentons ' tuning Triumphs ' book . Or else !
https://www.google.com/search?site=imghp...ch&imgdii=_

Do the Crank weights Match / heavyer'd be o.k. for Moto x /
mud plugging . Within 10 % should be o.k.

carveing em pistons'l alter the Balance Factor .
So Keep them exact ( useing a virneer to measure )
as it doesnt matter a toss , unless its miss balanced .

Last edited by Pre Unit; 04/03/14 12:17 pm.
#536473 - 04/03/14 11:05 pm Re: Pre-unit T100 with 650 crank shaft questions [Re: Pre Unit]  
Joined: Apr 2006
Posts: 261
RGSDave Offline
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RGSDave  Offline
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Posts: 261
Kansas City
Originally Posted By: Pre Unit
Heres a picture ive flogged from a T100r 1955 thing here .

http://i244.photobucket.com/albums/gg15/rgsdave/P1030754_zpsa029632f.jpg

saying its a Std 54 crank & 9:1 pistons .
-----------------------------------------------------------------
The 55 t100r introduced the Big Bearing Crank / case .
bulge under timing cover. same Brg. L & R . cases .

The balance factor is a consideration . some think 72 %
in your expecting it to go better than new W.F.O. .

The 61 T120 rods wernt as beefy as the later ones ,
but I found perfectly adequate at 8.000 + regularly.
DESPITE others gripeing . Less INIRTIA .
likewise excessive dome in pistons MASKS CHAMBER & impedes combustion . the 9.5 650 pistons are likely the optimum crown
shape . run at 9.75 measured dont hang about .

The 55 100R was redlined at 8.000
A measured 7.25:1 saw this repeatedly .

despite not running the necesary .010 clearances & 40 BTDC Ign.
performance loss Av Gas to Pump gas was discernable.
As was kick back bump starting without retard on pump gas .

Low crown pistons and C.R. measured 10:1 Max with your extra 1 mm throw should be simple enough . Id run a reversed 750 Oil pump . dual 1 1/16 carbs .


Pre Unit,
Thank you very much for all of your information. I am by no means an expert on building these engines. I learn something new every day and every bit of information is beneficial in my opinion. My '54 engine has been temporarily put on the back burner in order to complete my '55 T100R which will be put back together to stock specs using the '54 crank. The '55 R will never be pushed to its limits while I own the machine. I know that it sucks to hear, but I'm too invested in it.

On '55 being the first year for a big bearing crank & cases, I'm not sure, but I have a '54 T100 big bearing crank & cases.



Following is the 54 T100:


Following is the 55 T100R:


The cases look the same to me and both have large journal 3 piece cranks.


Once again, thanks for all of your information.

Dave

#536483 - 04/04/14 12:54 am Re: Pre-unit T100 with 650 crank shaft questions [Re: RGSDave]  
Joined: Feb 2014
Posts: 40
PatrickMcG Offline
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Joined: Feb 2014
Posts: 40
Australia
Some nice engines there dave

I tried to PM Pre-Unit but your inbox is full.
I was wondering where you got your titanium bolts for the 3 piece cranks. Can you get original size or did you drill them out to fit a larger size? I cant get a billet one piece so im trying to build the strongest 3 piece crank I can. As its going to be the weak point in my racing motor. Cheers

#536508 - 04/04/14 9:10 am Re: Pre-unit T100 with 650 crank shaft questions [Re: PatrickMcG]  
Joined: Jul 2009
Posts: 3,549
Pete R - R.I.P. Offline
In Remembrance
Pete R - R.I.P.  Offline
In Remembrance

Joined: Jul 2009
Posts: 3,549
Vic. Australia
I wouldn't be using titanium bolts.I'd use something stronger,like high tensile steel grade-8 bolts.

#536511 - 04/04/14 9:29 am Re: Pre-unit T100 with 650 crank shaft questions [Re: PatrickMcG]  
Joined: Nov 2011
Posts: 257
Pre Unit Offline
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Pre Unit  Offline
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Joined: Nov 2011
Posts: 257
terra Australis
Opps . Just cleared it .

Young Livingston threaded some Ex DC 10 ( likely ) N F Bolts ,
for the price of a tap .

I. E. cut bolts of std. Dia to studs , and threaded ' ex head end

Figured itd tear up the tap but wanted a play as it sounded exotic .

used 12 point nuts ( new ) ex Air New Zealand ,

Had assumed a 7.000 redline , but in hindsight I recall
from the corner of the eye the needle hitting eight odd,
in second & first on the club circuit .
Pulled up to 7600 in top o.k. before throwing out the picks,
on the Grand Prix circuit , after Id buttoned off at 7200 &
pulled it back to 7000 .
was passed by a dodgey crank blokes alcohol T Bird . Red Mist .
and a hard left . so presumeably the old girl wouldve run past
that in top , there . Given a chance . Gearing was 120 @ 7000 .

Quite frankly , went through the same mental parambulations
at that time regarding paranoia & bottom ends .

Mine ran standard eight ( from 58 odd ? ) big end shells
presumeably in the white metal rods . But had previously had a new timing side case . Previously last raced 64 or earlyer .
The Shells were ' file ' clearanced for the big end bolts ,
and the bolts ground to clear shells & or CRANK (shock horror).

Jo Mo Co Valves , 1 1/16 ports & carbs on long runners ,
of the line you were useing 4500 / 5000 . it bogging below
4500 / at 4000 . Against TZs & all comers
in the open 500 class.
As it cleaned the drag into the r/h sweeper , and my ' custom line ' into there ( as later used by the TWR Jags on the G.P. circuit )gave the best run onto the straight . Streamlineing added weight so the also runners dropped away *, though the
1100 Katanas in open prod got through ( or were let through )
after a few laps , into the hairpin .
Out of there with the C.R. Box youd decltch to get on the cam ,
Cork plate 650 clutch alowed a variety of tecniques . Generally
W F O as soon as straight end sighted .
Just rideing by feel ( the T120 had never had a Tacho )with
the odd glance at the needle . As it was at the start of my track endevours the mental digestion was on overload what with other things and all .Basically the project was sabotaged , but
observerd by TR 750 ' patron ' with the result
of some coercion to try the TR on that tack .

Easy to be wise in hindsight - more concerned to not scratch the paintwork on a museum piece of dubious reputation .

A decade or two of contemplation drwas the inevitable conclusion that the press is a pack of drama queens ,
and few pilots had evolved or matered the tecnique for
the tooned pipe F750 rice burners .

Which leaves us with ' A 2 1/2 % over capacity option ,
if fitting a Standard Journal .40 inch crank to the .30 .

If you wished to compromised by paranoic number crunchers ,
youd offset grid the 650 crank 1 mm to destoke ( .040 ) .
But Id see such expense and persnickitytness as political missapropriation or the intent of the movement .
to GET people On the TRACK .
Even if theyre destitute .

There are theorys and theorys , a overoptimised engine that
is to critical to ever run correctly, thats overbuilt .

And a proven antiquity thats given the benefit of a few bits
to enhance the durability ?

Thus the Low Crown & Light rods in the hands of a young maniac
with the benefits of a tuned exhaust can give unforseen ( to some ) benefits . Combined with Good Brakes , Light Weight ,
Good Tyres ( larger than P. R. Triumph Triple on rear & KR 76 front , in the Good Compound & ' R ' caseing rear ). combined
with good chassis geomety & dynamics .

Last edited by Pre Unit; 04/04/14 9:32 am.
#536512 - 04/04/14 9:31 am Re: Pre-unit T100 with 650 crank shaft questions [Re: Pre Unit]  
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Posts: 257
Pre Unit Offline
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Pre Unit  Offline
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terra Australis


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