The BSA A7-A10 Forum

Technical => A7 & A10 Engine => Topic started by: Lukey on 08.08. 2015 17:36

Title: Building a less than standard engine!
Post by: Lukey on 08.08. 2015 17:36
Good evening one and all!

Some may of seen my ongoing thread about my caferacer build!

My next job is building up my engine!

I am after building a quick engine BUT not to the limit its unreliable and likely to go BANG!

I plan to fit 9:5:1 Piston's
Spirtfire Cam
Needle Roller Bearing conversion on a Large Journal Crank
Polished conrods
Alloy Head
Thick Flange Barrels

What else should/can I do?

Also I am struggling to source good quality 9:5:1 pistons? anybody recommend a good place to get them?

Many thanks in advance  *smile*
Title: Re: Building a less than standard engine!
Post by: chaterlea25 on 08.08. 2015 20:55
Hi, Lukey

Quote
What else should/can I do?

Cake st Classics can supply Wiseco pistons, I think they are 9:1
For reliability and todays shit petrol thats high enough, (my opinion)
I know BSA had 10:1's but have not seen 9.5's
Sometimes NOS ones come up on fleabay

I would recommend new conrods, crack testing the crank  and dynamic balancing

A Gold Star valve spring conversion is/was recommended ,
http://eborbikes.com/

A lot depends on you budget, ?? twin carb head/ high flow valves , porting, carb ??  ignition system?

lightweight parts??  polished and lightened rockers / pushrods ??

Have you seen this link ? http://bsa-a10.hailwood.com/index.html

The Skys the limit *work*

HTH
John





Title: Re: Building a less than standard engine!
Post by: Viking on 10.08. 2015 09:51
I have a Super Rocket with RGS tuned engine, with spitfire cam and 10:1 pistons.

The fuel available today is not in favor of too high compression.
You need octane 100 or octane booster for this.

I had to lower the compression on my RGS engine, to make it stop pinking. ( by installing a spacer under the cylinder !).

Take into account that the alloy cylinder heads we can find today (more than 50 years after end of production) has been shimmed several times in there life !
This rise the compression even more. !

A new high flow oil pump plus new oil pressure relief vale from SRM in Wales is a must today.
The new oil pump benefits with higher oil flow and stop wet sumping.

I use a manufacture new  (from 1998) 389 monoblock 1 5/32” single carb. This setup works very well and has a crisp and quick throttle response.

It is not advisable to use twin carb setup. You can gain a little, but it is very fiddley and you end up with constant adjustment of the carbs.
Finding a good A10 head for twin carb installation, is not realistic today...
   
For valves and guides in the cylinder head, use modern vales with a higher degree of filling, and convert it to lead free in the same go. with oil seals on the inlet valves.
The cylinder headshop in Webley, arranged this for me I 1995, and this setup works sweet… 

Dynamic balance of the crank is a must.

Pay attention to the cam followers, they ware out. SRM can deliver new units.

The SRM oil/ roller bearing conversion is a must on a A10 engine. The turns a good engine in to at strong and very robust engine. 

Ignition:
Magneto is periodic nice, and look right. But it is endless fiddling and troublesome on a 50 year oil bike used only now and then.

Problem I have encounters with rebuild magnetos:
( Rebuild several times by a company in Sheffield and SRM, regardless of cost !)

Uneven ignition on the two cylinders, weak spark from start. Hard to start with the fuel quality available today. Need constant attention.
Last 5-6 years, and need to be rebuild again. 500 £ each time !!

Go for electronic ignition. It is accurate, bullet proof and give a much improved ignition.
Setting up correct ignition time on the magnetosystem is a night mare...

If the dynamo is old and worn: Go for a Alton AC generator unit with chain drive (belt drive give trouble).
This unit works very well and can give you H4 modern light.

Avoid 6V.  Getting long lasting bulbs and equipment is a challenge.
All contactors burn out and last short time with 6 V.

I have BSA, Norton and Triumph. Some with 6 volt and some with 12 volt. All rebuild by me.

I regret my then stubborn attitude in the 90ties and keeping with 6V positive earth.  !

If I was to rebuild again, it would be 12V with negative earth, using a Alton generator and electronic ignition or if possible AC crank mounted generator for my Triumph T110 or my Norton.

With belt drive and dry clutch.


Viking, Denmark.

BSA A10 GF, SR & RGS
Title: Re: Building a less than standard engine!
Post by: duTch on 10.08. 2015 10:25
 
Quote
Take into account that the alloy cylinder heads we can find today (more than 50 years after end of production) has been shimmed several times in there life !

  Hiya biking Viking; at risk of having my own head done... *fight*..I think you mean "more than 50 years after end of production) has been SKIMMED several times"..hence a need for shimming..???
 ..sorry, but that's how it is *smile*
Title: Re: Building a less than standard engine!
Post by: rocker21 on 10.08. 2015 17:54
many years ago back in the 60's i built a very quick A10 , it had the needle roller conversion and it was done before Devimead (hope i spelt that correctly) started doing it, 9:1 pistons as that was the safe maximum, the engine ran on needle rollers for the cam, idler shaft etc, there was not a bronze bush in the engine, it also had what was then called a polydyne cam which was made by somerton ( not sure if i spelt that correctly) it it was an animal of a cam , much modified head etc and it was very quick but had no bottom end it was a box of revs and was not really suitable for the road, it took several attemps to get it reliable and i still have that engine in the loft but it would be no good with todays petrol, it used to break the 8000 rpm rev counter and i ended up with a Krober electronic one as that went to 10000 rpm , I am hoping to make a bike for having a go at hill climbs with this engine just for a bit of fun and run it on avgas for compition use. it had so many mods can't list them all here , like crank and conrods modified with shorter rods and bit machined of the top of the block to allow for the short rods, balanced and lightened flywheel  and the list goes on.  it was a lot of fun making it and my local machine shop got to know me well.
Title: Re: Building a less than standard engine!
Post by: muskrat on 10.08. 2015 20:50
G'day Lukey.
If you do all of the above you'll have the fastest road going A10 on the planet.
A couple of sites for info http://atlanticgreen.com/bsamain.htm  and http://bsa-a10.hailwood.com/
Cheers
Title: Re: Building a less than standard engine!
Post by: Viking on 11.08. 2015 08:52
I have a BSA A10 with RGS tunes engine.

9:1 compression and BSA A10 spitfire scrambler cam.
Late type alloy head with big valves and 389 mono bloc 1 5/32”
SRM oil and bearing conversion.

Primary gearing changed to 23 tooth, standard solo gearing on gearbox and rear wheel.

Pull like a train, with loads of bottom torque.

Excellent in town driving etc. and quiet on A & B roads around 50-60 mph.

It is the best of my brit bikes. I have a Triumph T110, but it have nothing like the same low down pulling power as my RGS engine…
A proper A10 tuned engine is a treat..


The only issue; if accelerating very hard in 3rd. gear it can jump out of gear.
So a hard tuned A10 engine need a super clutch and a heavy duty gear box.
Title: Re: Building a less than standard engine!
Post by: rocker21 on 12.08. 2015 12:21
never had any gearbox problems, certainly had clutch probs and back in the 60's there was not the options that are about now, i had a modified 6 spring clutch that had solid disc's of friction material rather than steel plates with inserts, still got some in the loft and got a set in my A7ss works well but i don't think you can buy them now. if any knows were they can be bought i will buy some as they make a huge difference to the clutch.
Title: Re: Building a less than standard engine!
Post by: worntorn on 12.08. 2015 19:45
I have a BSA A10 with RGS tunes engine.

9:1 compression and BSA A10 spitfire scrambler cam.
Late type alloy head with big valves and 389 mono bloc 1 5/32”
SRM oil and bearing conversion.

Primary gearing changed to 23 tooth, standard solo gearing on gearbox and rear wheel.

Pull like a train, with loads of bottom torque.

Excellent in town driving etc. and quiet on A & B roads around 50-60 mph.

It is the best of my brit bikes. I have a Triumph T110, but it have nothing like the same low down pulling power as my RGS engine…
A proper A10 tuned engine is a treat..



The only issue; if accelerating very hard in 3rd. gear it can jump out of gear.
So a hard tuned A10 engine need a super clutch and a heavy duty gear box.


Would thi s engine be any different than a late Super rocket engine? I often see reference to " RGS Tuned" or in magazine reviews of the RGS see the engine referred to as a "Tuned" Super Rocket engine. But isn't it the same engine as the 61 on West Coast US bike, 9 to one CR, same valves, same 1 5/32" Carb and same 357 cam?


Glen
Title: Re: Building a less than standard engine!
Post by: trevinoz on 12.08. 2015 22:28
Yes Glen, it is the same engine.
Title: Re: Building a less than standard engine!
Post by: worntorn on 13.08. 2015 02:55
Thanks Trev, it can get confusing. One article suggested that the late Super Rockets produced 46 BHP while the Rocket Gold star could "produce as much as 50 BHP when fitted with the RRT2 close ratio transmission"
I'd love to hear the author's explanation of how the transmission could make the engine proudce more horsepower at the crank!

Glen
Title: Re: Building a less than standard engine!
Post by: duTch on 13.08. 2015 09:08

 
Quote
I'd love to hear the author's explanation of how the transmission could make the engine proudce more horsepower at the crank
yeah, wondered that too.. *conf*
Title: Re: Building a less than standard engine!
Post by: trevinoz on 13.08. 2015 22:26
I think that you will find that the increased power was due to the "track silencer", not the transmission.
Title: Re: Building a less than standard engine!
Post by: chaterlea25 on 13.08. 2015 22:35
HI All,
As Trev says, but there should also be a gain from the needle roller equipped RRT2 gearbox ? less friction!

I know Gold Star engines were individually bench tested and had to reach a certain BHP before being fitted to the cycle parts, but there were still engines that comfortably exceeded the required mark
A debatable point is were these engines then put aside for favoured customers/ dealers??
I have often wondered but have not researched whether RGS engines were bench tested /alllocated in such a manner??

Cheers
John
Title: Re: Building a less than standard engine!
Post by: trevinoz on 13.08. 2015 22:51
John,
                I'm pretty sure that gearbox bearings wouldn't make any difference to engine power output which I think was measured at the crankshaft.
As to the RGS engine allocation, that is an interesting question. Rocket engines were always tested and the test sheet was supplied with the bike.
If you read the original RGS road test, it didn't perform any better than a Super Rocket.
As a matter of interest, a friend bought a Big Valve Super Rocket new in 1962.
It had 10:1 pistons and an output of over 50 BHP. There were two delivered to the same dealer and the horsepower was slightly different on the other, a bit higher than my friend's.
Trev.
Title: Re: Building a less than standard engine!
Post by: chaterlea25 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
Title: Re: Building a less than standard engine!
Post by: Rocket Racer 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.

Title: Re: Building a less than standard engine!
Post by: chaterlea25 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
Title: Re: Building a less than standard engine!
Post by: Rocket Racer 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...
Title: Re: Building a less than standard engine!
Post by: jjbsa 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!
Title: Re: Building a less than standard engine!
Post by: peter small 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
Title: Re: Building a less than standard engine!
Post by: Viking 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 
 ;)
Title: Re: Building a less than standard engine!
Post by: muskrat 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
Title: Re: Building a less than standard engine!
Post by: Rocket Racer 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*.
Title: Re: Building a less than standard engine!
Post by: Klaus 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
Title: Re: Building a less than standard engine!
Post by: peter small 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.