Author Topic: Building a less than standard engine!  (Read 2761 times)

Offline chaterlea25

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Re: Building a less than standard engine!
« Reply #15 on: 14.08. 2015 00:43 »
Hi Trev,
Quote
          I'm pretty sure that gearbox bearings wouldn't make any difference to engine power output which I think was measured at the crankshaft.

I had forgotten that  *red*
My brain had rolled forward 50 yrs to rolling road dyno's  *eek*

John
1961 Super Rocket
1963 RGS (ongoing)

Offline Rocket Racer

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Re: Building a less than standard engine!
« Reply #16 on: 14.08. 2015 05:19 »
Lukey,
if you're building a fast road motor the short rod option is a good one, it allows you to run the late A65 steel capped alloy rods and help give the engines a bit more snap as well as access to assemble the rocker boxes and will have all the fin counters convinced its an A7.

Likewise with all this talk about power loss, a decent belt drive reduces friction loss and good for those quick take off wheel stands at the lights.
If everything else is apart always worth making sure the gearbox layshaft bushes are in good nick and consider fitting a 520 drive chain if the sprockets are naff.

A good rider periodically checks all nuts and bolts with a spanner to see that they are tight - Instruction Manual for BSA B series, p46, para 2.
New Zealand

Offline chaterlea25

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Re: Building a less than standard engine!
« Reply #17 on: 14.08. 2015 23:34 »
Hi RR
I see you have stuck with the "standard" valve spring setup on that head??
Any particular reason for this and not going for the goldie spring conversion?

Regards
John
1961 Super Rocket
1963 RGS (ongoing)

Offline Rocket Racer

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Re: Building a less than standard engine!
« Reply #18 on: 17.08. 2015 03:49 »
Hi RR
I see you have stuck with the "standard" valve spring setup on that head??
Any particular reason for this and not going for the goldie spring conversion?

Regards
John
no particular reason, good question...it still pulls through to 7500 readily, for that matter the timing gears are not lightened, nor the rocker arms polished. Its a pretty stock motor apart from the short steel capped alloy rods and a bearing conversion. Pulling a chair means the engine works very hard through the range compared to a solo and its currently the quickest 650/4 speed outfit on the track. - although most of the triumphs are now going big bore... so I could really do with more cubes
There is more tuning left in this motor but am slightly over committed with 6 BSA's in the shed (2 are my daughters) to maintain and my sons basket case '66 mini. so absolute fettling not likely to happen on my watch, unless I win lotto and retire to the workshop. Once somethings going strongly it tends to get left.
Current race money is going into rebuilding my front wheel (new hub drum centre being fabricated) and the SC gearbox to get me back on the track for October.

The head is A7 and had a mixture of collars and collets originally fitted, which shat themselves (as I hadnt realised they were mismatched -I removed 26 collet pieces and some bent valves after its first meeting) so bought stock parts to get the long rod motor back out racing and havent reconsidered as it does the job. 
The Bob Newby clutch is a godsend, allows the bike to get its power down hard off the starts and it usually lifts the front wheel which seems to get us off the line quicker than if we spin up the rear tyre. That was a sound investment.

I guess there's always more left in the pot, the question is will it cut my laptimes or should I just eat less pies...
A good rider periodically checks all nuts and bolts with a spanner to see that they are tight - Instruction Manual for BSA B series, p46, para 2.
New Zealand

Offline jjbsa

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Re: Building a less than standard engine!
« Reply #19 on: 19.09. 2015 13:49 »
My RGS has been on the dyno a little while back.  It has carefully ported inlet tracts, single 1 and 3/16" Monobloc carb, genuine BSA Spitfire cam and BSA followers, Ebor valve springs and alloy valve collars, Wiseco 9:1 pistons, 37 degrees ignition advance, Shell V Power fuel, Avon GP rear tyre at 25 p.s.i., RGS Siamese pipes and track silencer: this gave 43.6 rear wheel HP at 6,200 rpm and a nice flat torque plot.  I used Torquetune for this work because they are used to testing classic racing bikes on their Dynojet dyno. We believe there may be more to come because on the day, the Monobloc could not deliver more fuel.  The window I put in the float chamber showed the carb could not fill up fast enough by the time the motor was revving high.  I have since solved this problem and I intend to do more tests.  The bike is very enjoyable to ride.  Dyno rooms get very noisy!

Offline peter small

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Re: Building a less than standard engine!
« Reply #20 on: 19.10. 2015 19:52 »
I bought a RGS in the mid 60`s for £100 which had a twin carb conversion amal monobloc`s cannot remember the size but they were big belmouthed fitted with 11.1 pistons we could then get 5 star 100 octane petrol 4 gallons for a pound.
The rrt2 box was a pain around town but on the open road with no speed limit i clocked 115 mph riding at over the ton regularly.
On one occasion it blew the barrels to bits, i reduced the compression to 8 to 1 it was a much better bike and didnt go through clutch plates so often but still capable of well over the ton.
The clutch  had to be slipped up to 30mph and first gear clocked 70 mph before changing to second polished blue print conrods  eddie Dow trick bits alloy italian levers straight through big bore Dunstall exhausts Very  LOUD

All i can say is if you want a reliable bike dont over tune it you will spend loads of time putting it back together i did.
By the way it did 22 miles per gallon used to eat Goldies for breakfast

Pete
BSA ROAD ROCKET 650cc 1954
Norton commando Roadster 750cc 1972
Triumph T140 Silver jubilee 750cc 1977
Honda Pan European ST1100  2000
Honda C90 1990

Offline Viking

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Re: Building a less than standard engine!
« Reply #21 on: 20.10. 2015 07:26 »
22 MPG = 7,8 Km/l  *eek*  what....

My RGS does 21-22 km/l   = 71 MPG (UK gall)
If really pushing it, it drops to 18 km/l = 56 MPG

Did you use Edwards fuel taps.  They tend to drip a lot of fuel away 
 ;)

Online muskrat

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Re: Building a less than standard engine!
« Reply #22 on: 20.10. 2015 11:20 »
"All i can say is if you want a reliable bike dont over tune it you will spend loads of time putting it back together i did.
By the way it did 22 miles per gallon used to eat Goldies for breakfast"

Yep ^
My A7SS on methanol got 12 MPG. Expected at least one big bang per season  *problem* *pull hair out* *work*
Cheers
'51 A7 plunger, '57 A7SS now A10CR,  '83 CB1100F, 88 FXST .
Australia
Muskys Plunger A7

Offline Rocket Racer

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Re: Building a less than standard engine!
« Reply #23 on: 21.10. 2015 05:40 »
I take my hat off to the clever people who can build custom motors with homemade or a65 barrels and lightened everything, well beyond my capabilities of an assembler and maintainer of more bsa's than I can afford to...
So I like to keep my motors reasonably stock, so they have more margin in and touch wood my engines have hung together through some serious abuse  *whistle*.
No idea what the fuel economy is, I keep the small export tank semi filled every race. possibly 30 litres of Methanol gives me 30 laps.
I'd rather finish a race meeting with the bike intact and placing rather than go home with a smashed motor and a dnf, but it'll no doubt happen  *doh* and be a sad moment.
I've often found on the road my humble cooking B33 motor leaving in its wake far more capable lightnings that keep closing the throttle for corners   *shh*.
A good rider periodically checks all nuts and bolts with a spanner to see that they are tight - Instruction Manual for BSA B series, p46, para 2.
New Zealand

Offline Klaus

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Re: Building a less than standard engine!
« Reply #24 on: 21.10. 2015 07:53 »
I dont know the fuelconsuption of my racebikes and l chatch fuel only for one turn.

But one event something went wrong.
 First race with the Goldi l run out off fuel about 500m last lap to finish.
So l  lost the winner cup and being second place of all events of the year. *doh*

Last race with the A10.
We are standing a long time at the prestart, expekted every minute we can start, but there was an accident and they have to clean the trak.
I never mind to dnf last lap with no fuel *eek*

cheers Klaus


If you think, everything is under control, you are not fast enought.

Offline peter small

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Re: Building a less than standard engine!
« Reply #25 on: 08.11. 2015 23:14 »
You must remember it was the time of the Mods and Rockers as i said no national speed limits and we never heard of wet sumping as these bikes were ridden hard every day. no pootling about that was for scooters. (hair dryers)
We had two speeds fast and faster. Traffic volume were nowhere near what they are today.
I can remember one rebuild the bike vibrated enough to blow the head light bulbs almost every week, so the crank was taken to work and placed in a lathe, an old engineer hit the crank with a hide hammer and it ran true no more vibration. There was a lot of good engineer around.
Never left the house without a tool kit in my inside pocket of my leather jacket. wish i had the bike now 100 per cent grin factor.
Never wanted a Triumph ,own two now still love the Beeza sounds better.



BSA ROAD ROCKET 650cc 1954
Norton commando Roadster 750cc 1972
Triumph T140 Silver jubilee 750cc 1977
Honda Pan European ST1100  2000
Honda C90 1990