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 John, Mark, Genesis-- Apostolic intervention ?

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Trevor Amos



Number of posts : 860
Registration date : 2010-08-13

PostSubject: John, Mark, Genesis-- Apostolic intervention ?   Mon Oct 03, 2011 9:26 pm

Hi, john B,
Delighted that you were impressed by the power and acceleration of Mark`s bike , and, starting from 44 on the grid ,out
dragging all the 125s and 175s then taking on the 250s is certainly noteworthy !
Just to dispell any doubt there may exist for the legitimacy of this engine , it`s bore and stroke remains at 54x54
The piston and rod assembly are the only foreign parts in it , and , not yet at least, Chinese in origin .
The crank was made by me here in sunny Somerset , as indeed was the cylinder barrel / liner , head /water jacket
and clutch body , and it`s genesis - 1994 , oh, and the crank is 96mm in dia and weighs 2.5 kg !
Returning to Eric Walsh , the fasinating book by Bill Lomas details at lot about the exploits of both him and Dickie Dale
down in Oz ,and, Eric`s Bantams . Perhaps interestingly, and certainly with a high degree of intrigue was the departure
of Bill to the UK. Eric was there to wave Bill off and thrust a heavy parcel in his hand and then was gone . When later
the parcel was unwrapped it proved to contain a Walsh Bantam cylinder and con -rod assembly. So, somewhere lurks a
piece of Bantam history , anyone up for tracking it down?

Finally , on to the 320 Guzzi ,to get the best overall track perfomace, internal gear ratios were juggled with external
flywheel weight and diameter , and if one section of track proved difficult ,that was concentrated on to the detriment
of somewhere else , getting the best from what you`ve got .In that respect not too dissimilar to setting up a Bantam ,
and despite giving 30cc to the opposition they were fearsomely quick .

Thats all for now ,regards Trevor


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Edward Pickering

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PostSubject: Re: John, Mark, Genesis-- Apostolic intervention ?   Mon Oct 03, 2011 10:39 pm

Hi Trevor,

Have to agree with John, was great to watch from the mountain and a credit to your engineering. Sounds great on the pipe and i could be wrong but also running on an amal mk2.



Kind Regards


Eddie
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john bass

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Age : 88
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PostSubject: No intention ...   Mon Oct 03, 2011 11:01 pm

No intention to provoke a probe-of-enquiry Trevor -- just impressed with the way it flew off the line whilst some Bantam riders were frantically `paddling´.
What are the max revs? or is it a secret?

The Walsh Bantam didn´t have a rev counter and Maurice Quincy said it would just rev on and on. Quite a rough looking thing with mega and crudely sprung rear wheel.

It was, of course, using a methanol derivative which as I know it, gives a longer Heat Release period starting with a lower peak pressure (than petrol) which means less opposition to the piston rising on compression which enables the max revs to increase although the compression-ratio was around 16:1.

I wasn´t sure where to put the commas in that so I shall leave it be...

Good luck!
Cheers!
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john bass

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PostSubject: PS -- Trevor...   Tue Oct 04, 2011 3:21 am

Trevor!
Its marvellous -- making your own con-rod & crank-assembly , I mean.
I would have been very happy to have been able to make that statement.
It is you blokes with that sort of know-how who are perpetuating the Bantam beyond the level of QUB***which was after my Bantam beginnings ....

Con-rod length does come into play relative the most advantageous crank-angle for combustion and expansion ...

And, of course, my old sponsor -- Andy Boyle -- on the 250 ABS who has the RE GP5 -- and now makes the Royal Enfield GP5 replica motor almost from scratch with mouldings for engine castings and so on -- is also aiding the perpetuation of Historic bikes...
He and Brian White got together on the Wednesday after Cadwell which could be a good thing for the sport ....

What´s puzzling for me is that things seem back to front from what they were.

It used to seem right to have a low static 2-Stroke (measured) compression-ratio that would allow the engine to rev-on and tune the ports to get a higher dynamic compression-ratio higher up the rev band -- which is what the resonant pipe does, of course -- but I read Mike Powell´s comment of 12:1 c.r. ...

Previously I made the comment about 16:1 compression ratio on the Walsh Bantam with that latter point in mind. How the hell did Walsh get it to be so quick with a megaphone exhaust? -- or was it that all the others, including 250s were slow?

I calculated that a 96mm crank assembly weighing 2.4kg at 1200rpm would have 2,180Joules of stored energy and a 200mm x 4.5kg would have around 11000Joules at 9500rpm -- sort of roughly 5 times as much at 2,500 rpm less....

So, WHY does the the 175 need the large flywheels??

I think I know but would like to hear other opinions first.

I wonder when and if we might see a Bantam with an external flywheel?

What about an extrnal flywheel with a de-clutchable device -- or even detachable -- once the good start has been made ....??

***Queen`s University Belfast -- who were early developers of the two-stroke incorporating the reed-valve...

Sorry this is so long but I got `Took´....
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ted

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PostSubject: Cadwell   Tue Oct 04, 2011 4:34 am

Hi Trevor I am guessing Steve ether could not remember what happened in the bar or he did not tell you. My friend, who has not been to many BHR meetings, said after watching the bantam race “I think they should measure his motor”. My reply was it’s not the motor that they want to measure it’s the ability. That goes for design, riding and build. Well done on producing a good quick and reliable motor straight out of the box. Count Augusta used to say the best way to make a good bike even better was to put a fast rider on it. You posts are little gems to.
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Trevor Amos



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PostSubject: Re: John, Mark, Genesis-- Apostolic intervention ?   Wed Oct 05, 2011 12:55 am

Hi, Ed, Ted and John.
Thankyou all for the kind comments , it`s on occations like this that show what a good place the forum
is what thoughtfull peoples contributions make it so !

Spot on Ed , Amal MK2 i cannot understand why it`s not more popular ,dead simple to dial in and
makes the power what more do you want?

11000 plus John, cant be more precise as the reading goes walk about as the revs increase, really need
a new one but have to think cost, racing is expensive and little luxuries have to be put to one side.

60-90-108mph, in gear speeds for the Walsh Bantam from Bill Lomas in his book. Dickie Dale got hold
of some trick piston rings , from the UK, that solved the wear problem you high lighted earlier which
bedeviled Eric`s efforts .

Try looking at the 175 problem from the reverse end, if you were to design a new engine would it be
the same as is , if not what would you change and, there, could the starting place for solving the conundrum.

A very astute observation there Ted, a clever analysis , dead right of course , and no, Steve didn`t mention
any of that , still on a bit of a high i expect !


Catch you all again later , regards trevor








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Edward Pickering

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PostSubject: Re: John, Mark, Genesis-- Apostolic intervention ?   Wed Oct 05, 2011 6:28 am

Hi Trevor,


Credit is given where it is due so you more than deserve it, well we have amal mk2's from what dad has collected so we are gonna try them and see what happens.

We are not engineers or have any skills but we have enthusiasm, hence why a thing that maybe able to be made within the club easily or knocked up in a weekend by a experienced racer is something we in honesty are taking far too long about.

We will get there and are enjoying it along the way, without the forum we would of thrown the towel in long ago or just not bothered.


Apologies if this moves from the original specific topic thread.


Kind Regards



Edward & Malcolm Pickering
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john bass

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PostSubject: Starting from where?   Wed Oct 05, 2011 9:04 pm

With a 175 I´d make it a six cylinder monstrosity with a de-clutching contraption to an exterrnal flywheel of enormous proportions so that the flywheel could be spun up to enormous energy and the energy fed in by computerised control when required...

Right Nick B -- JayBee is bullshining again --

BECAUSE Trevor! I JUST WOULD NOT KNOW WHERE TO START??

my forté -- like the Japanese & Chinese -- is developing something already started...
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john bass

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PostSubject: Trevor! you ...   Tue Oct 11, 2011 5:32 am

Trevor -- you and your blasted conundrum!?
The thought keeps recurring...

If I were redesigning the 175 ...??

Well, if all things were to stay as they are: formula as is etc ... etc... and
we now know that a big flywheel is necessary in the 175 (for acceleration from start) and not in the 125 -- I´d think about reducing mechanical losses to an absolute minimum relative reliability. Since piston & ring(s) make up over half of
the mechanical losses I´d concentrate on that as a priority since piston diameter
is the major distinction between the 125 and the 175 -- as far as I know.
So for a starter I´d endeavour to find out all about materials for piston running surfaces an low friction cylinder bores....
But I´d probably get peed off with that and go for KERS (declutchable flywheel
preferably) and Airbox (much neglected on 2-strokes) and Ejector Jet Assistance.

Eh?
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Bill Lomas Mcs



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Registration date : 2015-12-22

PostSubject: Re: John, Mark, Genesis-- Apostolic intervention ?   Wed Dec 23, 2015 2:25 am

Trevor Amos wrote:

               Returning to Eric Walsh , the fasinating book by Bill Lomas details at lot about the exploits of both him and Dickie Dale
               down in Oz ,and, Eric`s Bantams . Perhaps interestingly, and certainly with a high degree of intrigue was the departure
               of Bill to the UK. Eric was there to wave Bill off and thrust a heavy parcel in his hand and then was gone . When later
               the parcel was unwrapped it proved to contain a Walsh Bantam cylinder and con -rod assembly. So, somewhere lurks a
               piece of Bantam history , anyone up for tracking it down?
             
       

                   

Hi, I came across this post whilst searching for something else, I have the Walsh Bantam cylinder and conrod mentioned here.. I found this whilst sorting through my late Fathers  ( Bill lomas ) effects ..

I have tried to add a link to post photos but your system doesnt seem to allow it ??



if anyone would like these they are for sale to a good home that will appreciate  them  1 Very Happy
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Trevor Amos



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PostSubject: Re: John, Mark, Genesis-- Apostolic intervention ?   Wed Dec 23, 2015 2:51 am



Great news, what a fantastic find, so glad you got in touch. This is the only image I have of your father, at speed on the Walsh Bantam. If you have any more photos of him in the Bantam context we would love to see them!
Jumping from the big V8 to the humble Bantam must have been quite bewildering to get the brain around, but then if you have Bill`s talent anything is possible.

Many thanks, Trevor
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john bass

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PostSubject: Bill with dustbin fairing...   Wed Dec 23, 2015 4:10 am

Somewhere in young  Edward´s files is a pic of Bill using the dustbin fairing on a Bantam  in Australia....

You are not alone Bill Lomas jnr (sorry, didn´t catch your first name...?) in not being able to send pics -- we rely on Edward Pickering who seems the only one on here with the right fingers (and is it brain, Edward?) who can post pics on here ...

When i get a bit depressed I get out your Dad´s articles on his time at Royal Enfield and his racing exploits -- really cheers me up since Wilson-Jones (Enfield´s Dev Engineer) gave me the pip too....

Go well and keep well,
Cheers!
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Bill Lomas Mcs



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PostSubject: Re: John, Mark, Genesis-- Apostolic intervention ?   Sat Jan 02, 2016 7:53 pm






picture of the Walsh Bantam cylinder and conrod
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