returning to bantam racing

SOME GOOD QUESTIONS

Yes Brian is doing some really interesting stuff, can not help but admire the bloke, and what he does did you see the work in that stell clutch end plate.?? phernominal.!

carbs 30.8mm mikuni and the other that is not being used is a 34mm, the 30mm has been converted to a power jet with the help from Allens performance Carbs and Alan brown - great job cheer's Al" I owe you.

MIKE interesting obserfations and many questions, when you answered all my question I will be sure to answer "all" yours.
question"s
1) inspecting the frame for weld "NO" no, trying to work out how much weight advantage swapping the frame tubes as per Ned's post. works out to be considerable weight saving - approx 14lbs?? mike please clarify this is a legal mod, before I embark on such costly process.

2) water cooled crankcase/ reed motor yes it is a runner, raced and sprinted, we are in the process of building a new barrel, for it to finish, I had asked Trevor Amos for help with this barrel as it was an absolute flyer but has a designs fault, when I was experiencing all the broblems that contributed to me calling it a day. quite a few years ago.

3) pipe designed some time back, made a few alterations since, included while making it fit the bike specifically ref Alan Brown's help and Trevors advice (see tail pipe outlet inlet diameter - post).

4) foot rests on swinging arm, no sure why I did this, I can not remeber the reason, but it was a very popular method back in the sixties, if I do remeber, I will be sure to tell you all !!!!!!!!!!!!!!!!!!!!.

5)I agree best keep it simple, for reliability, test before you turn up, otherwise pure development can not be done during racing and expect to finish.

Hope I answered all questions Mike Tim.

TERRY are you Derek? Derek are you logging on as your dad?

Frame -I think its a legal mod as long as the tube you use is the same size and gauge as std.
ie not made of T45(thiner gauge?) which would be a great weight saving, or perhaps only for riders of 15st and above??

Some Frames of the recent past have had the lower tube cut out then put back in to the left at an angle - OK
A frame had its lower tube cut out and replaces by two smaller tubes(duplex) - not OK

Beware though the front tube of a bantam is double thinkness for 10"s from headstock.

Where do you get 14lbs saving from??

I see your water cooled motor had a Steel/braze water jacket head not alloy, what was the idea there??

Cheers TERRY

Regards Mike

wow , some of the pictures have blown my mind, especially the toilet seat engine cradle....... how can you follow through on that one? ...... obviously a solid design... yeah im totally wiped out ... tell me,
1) is it pine?
2) how thick is it?
3) can i get one from b&q?

Oi - Noggy - Those comments could only come from a Brummie- "well educated of course."?

regards

Derek

Hi Derek,

Nice response, though a 2-2-2 Miniature steam engine sounds good to me, home made I guess?

Got 1 more question though, with the barrel, what did you do around the crankcase mouth? Does look a lot has been changed there.. I probably couldn't do that lol... Need to work on the bike soon... Shame Dad managed to spend the funds of the bike on a new Olympus camera... f***!

Have a good day,

T

Frames- on at least some there is a tube inside the front tube, the inner tube is slash cut. A lot of people in the 60s removed the inner tube and bent the front tube(swan neck). I'm guessing later D175 twin web plates didn't have this inner tube. But I don't know??

Swinging Arms D1 don't have one! lol
D3/D5 s/a frame Don't know lenght but they are an inch longer than D7,10,14 and D(B)175.
D7- two frames early big lugs for side panels and heavy duty(looking) s/a pivot later ones skimpy lugs
lightweight(looking) s/a pivot. D10,14 etc the same as late D7?
Your frame in the pic is a heavy lugged one i see by your s/a pivot.

Regards Mike

Mr Betts!
Derek!
Pardon me if I got it wrong but I am sure I saw a mention you made of a Bantam named `Icarus´
which you said had a reed valve...
I put in this request a couple of days back and backtracking thro´ the messages here cannot find what I have just mentioned -- my PC is a bit of magic and often devours information, never to be seen again -- on occasion, it even forgets my name & password!!
...
So this is what I´d like to know -- if you knew of a Bantam named Icarus please tell me more about how you came to bump into it and what became of it...
There were two Bantams of that name: Icarus One with a fairing and the other -- Icarus -2, was naked. Both were long strokers and neither had a reed valve -- the QUB and its reed ... was just getting known to the biker fraternity at that time.
...
As I said before, when I got the Canadian Job offer I gave both to the Wobblyman, Colin Aldridge, telling him that one was for the club and the other to do what he liked with.
Although the experience with both was at times most painful I still have a soft spot for both and a longing to know of their demise and how other riders might have found the handling of Icarus-2 `unusual´*** which Wobbleyman reckoned was psycologically-lethal as well as being a normal killer.
...
***This was the result of a talk by Ken Sprayson which we both attended where Ken spoke of
"Centre Point Steering" and I made Icarus-2´s layout such that it would "Flop" into corners and was hard to pull back upright. Quite exciting until the rider got used to it....!

Cheers!
Daedalus -- father of Icarus-1 & Icarus-2....

hi john not sure it is icarus 2, but will post some pics when i get chance to you will not need to keep reminding me, as i promise i will post them pics, but i'm not going to tell you when??

so you will need to keep looking and posting in ?? ha ha.

regards derek

Further to previous post

175 swinging arms - there are two!!

One has a straight right (off/side) arm.
I don't know why which model? Competion? Bushman? Triumph Super Cub?

Thanks Derek!
Like I said the interesting thing about Icarus-2 was its handling. Reliability was awful because I got it to rev to 12thou plus with pistons that couldn´t stand the pace. They stretched so that the gudgeon pin was real sloppy in its bores....
In any case I had insufficient time*** to do a proper job with tuning although I thought I knew how.... like the idea was getting an optimum gas flow via the crankcase compression ratio and transfer port flow and a lower piston compression-ratio to rev on and on -- sometimes seemed almost there and it would go "Wuffle-Bang!"
...
It was fun(??) with Icarus-1 -- having Derek & Les assisting with prep although Icarus-1 revved to 8400 and no more unless getting a tow -- but I was never a road racer, I couldn´t get rid of the idea that the clip-ons weren´t wide enough and the desire to slide the corners -- sitting up -- would not go away.
...
Fairings were like a red rag to a bull -- yet I eventually fitted one to Icarus-1 (Icarus-2, ever the naughty one, stayed naked) and promptly crashed next day at Snetterton.

Cadwell was one of my favourite circuits but there are chronic pains in my left hand coming from the over-use of a spring-bound clutch and I can still experience the smell of burning oil and the clutch burning itself out on the way up to Charlies by just thinking, "Cadwell"...

Have a good season,
and mind the force of gravity,
Cheers!
JayBee.
***my excuse and I´m sticking to it.

Hi Mike was particularly intereted to know what the lengths are

regard Derek

Hi Derak,

Can do some measuring if thats any help to you.



Eddie

hi ed
looking at the amount of views i'm sure Mike will have seen this and have this crutial information in hand to post soon.

but thanks

come on Mike hurry up !

kind regards Derek

Mike did you answer this one if not can you please sure you have time -

O AND ITS BACK ON ? 4 weeks to go.??

regds Derek

Mike any good with those volunteer papers !.

Regards Derek

Do not know lenght of D3 swinging arm .... Edd can you measure s/a pin to rear wheel pin at sortest settimg and also s/a pin to rear shock absorber mounts .. have post D7-D175 lenght on this topic before ... look back derek

The D3 and D5 are 1" longer from pin to axle, strange when the D3 was made with 19" and D5 with 18" wheels.

No problem i can do that and hopefully if terry can come over on friday i can ask dad to get him to double check the measurements.


Eddie

Hi Derek,

Checked while your dad was here on my d3, swing arm pivot point to shock, 14. Swing arm pivot to spindle centre point 16.



Eddie

new topic was thinking about gears and gearbox recently

Interesting thoughts Derek.... When BSA were making the first batch of c/r gears I would think
they were planning for engine speed 6'000 and box speed of just under 3k.....
You have got me thinking....

thanks mike

kind regards Derek

I know everything Derek.... Go to Rex Caunt Racing website he does small engine sprockets for bants.
He says you need heavy duty clutch springs to cope with extra torque from the lower gearing from small
engine sprocket.
Mike

Derek, a very interesting proposal, to reduce clutch and main shaft speed, its a very relative thing perhaps for an individual engine setup what the overall torque reaction might be.
you are also right about dyslexic people being misunderstood, yet often having creative intelligence. It takes many forms, we are in good company, the late great John Britten for instance.

Mike, your observation is also appropriate. I have a 14T engine sprocket in my D7 (needs chain adjuster/tensioner) and a 12T in my D14 (48L chain) trials motors. They eat clutchs. The extra torque is very noticable, but 8 x 110 or 125% springs and heavy duty spring plate/alloy cover works OK. Ken has a 68mm bore motor, that is a real brute. Which is how the Suzuki clutch conversion came about; the smaller area plates need less spring tension.
The trials bikes, with extra "boost" transfers will accellerate fast at low revs and climb steep hills that require hard revving of my TY.

Shall have to try smaller 14Tengine sprocket in long stroke 175 on short circuits; 12T would be too low overall for racer.

Hi Mike quite right too

kind regards Derek