returning to bantam racing

Hi Derek,

Good to see you are able to crack on with the bikes, hope edward is enjoying helping and building his own bike and isable to get all the parts he is after

Eddie

Hi john only justs spotted these,

Kind - Regards Derek

Hi Derek,


Im the same with work hence why i am on at random times, we arent rushing too much as gonna try and get dad out on the red one so currently trying to replace the fork seals again and get the front brake working right or swap it for another and then hopefully try and take it out for testing. Gonna try and do a bit more on the blue one also.


Im sure you guys will pull it together and be ready in time.


Eddie

Hi Derek,


Hows the bikes coming along?



Eddie

port changes

we were out with the bike today.



Derek

could any one suggest a material that will survive the exhaust port btm face in the outlet we need to fill prefer not to weld it
we tried araldite bit it deternated the poston ring land away "by burning it away".


derek

Derek,
James Cook uses a resin called "JB WELD" in the inlet of the 175 and it seems to be rock solid, as far as I know it hasn't yet been used in the exhaust area, but I would be willing to have a go myself to see what happens!
You can obtain this stuff from EBAY quite easily but I gather it is not cheap. It seems to bond to the aluminium of the BTW barrels nicely and you can work it with a file or other tools reasonably well once it has gone off, plus it seems to cope with the expansion of the aluminium without any breaking away.
Could be worth a try?
If you are referring to changing the liner rather than the aluminium, then the only sensible thing I can think of is lasor welding as you can weld with similar materials and the heat and distortion is very minimal, I can recommend a company if this is the case. You will need to hand work the weld back afterwards.
Cheers,
Alan

Hi Alan
hope your well we contact you soon.

Thank you for this info.

I believe there is a SILICONE/CERAMIC powder mix on the market that I have been trying to find out about, apparently its used on comercial boiler exhaust repairs, and designed to withstand temp between 2000 and 3000 deg

I feel the araldite failed as a result of me over engineering (ref Bantam tuning manual suggestion to mix metal fillings in the araldite makes it stronger!) if I had not done this, it may have given better results, however I would like to look around before I try it again without the fillings, as the results were a high speed sezuire with no signs, but we have reduced the temp in this area (re- tailpipe and silencer diameter) it may be ok to try again.

does anyone know about or heared of this ceramic silicon product above, apparently its mixed with an epoxi/silicone type resign. ?

its running now with a 3 to 4mm exposure of the exhaust port at top dead ctr, killing the power we had on the dyno, I have say though it is so much easier to start now!.

regards Derek

for some reason these have gone missing for thou's who have asked, here they are.
regards Derek
















my weldings improving !


the important bit's?




can you spot the difference ?

to this

and this ?

Your public link is still on here and some of the other photos. I dont think you have enough gearboxes though.......................



Eddie

Dont know why this cropped into my head, is your fairing an original Todd one?


Eddie

yes original and from about 1963/64 I think !

Interesting collection of pictures and maybe I missed it earlier but its surprising nobody is asking questions about them.

Clearly they are not all the same bike / stable

The Blue fairing is a give-away and the numbers on the engine plates confirm that is one of Mike Powells bikes

The heavily modified (work of art) gearbox I believe is Brian Whites but how about some of the others?

Who has the re-shaped egg and how does the clutch under it perform ?

Who has found space to put all those ports in a barrel and how does it go ?

and how about the final picture of a watercooled crankcase reed engine - who did all that work ?

Mick

It´s me Mick!

I wanted to ask questions but felt I´d yapped too much on here lately to no real
purpose and I am very shy -- you know -- to ask questions which would show
my ignorance!

Yes! I hope someone explains....

I am still trying to get a PV diagram to appear but it doesn´t happen. Of course
this PC is all in German and I haven´t yet got the hang of some weird terms which
have had me post pictures I would have not posted on other websites even more
pious than than this....

regards Derek

Hi Mick

lot of photo's and too much information

Kind regards Derek Betts

Just to make it perfectly clear, the words above, repeated in the quote below are not my words but those of Derek Betts

Quote :

The answer to this last one is "me", many many hours, the crankcases are actually early type D1, I picked these because I noticed the crancase walls were thicker, I believed stronger, I actually heat-treated the whole lot after initial welding, and rough machining, The welding guy use to fetle the pistons on our production line, before machining, but he was a great welder, I did all the main bearing bores and spigot on a KTM Horizontal cnc machine centre with a 2000 Kongesburge control, over a weekend, many hours were spent machining it, I got dad to lap the faces then he hand scrapped flat to the clutch face, that I then bolted off to do all the machining, line boring all the bores and g/box, we fitted a larger bearing on the output side and used a stepped support to hold its, that was dowelled in position, the btm end is very accuratly machined, and works fine, its was just the barrel.

The barrel started life as 175 D7, I made the first liner, from a "spun alfin ring, ci9 Iron", the outer transfers were machined from a solid piece of steel, by machining a bowel then cutting out segments for each side, an exhaust port was rolled from a sheet of thick steel and it (waiit for it) "was all brazed" onto the cast structure, we left as many fins on the barrel to maintain strength, anyway we eventually gave up with it, untill we had time to resolve its issues, that were all down to a number of fundermental errors while going though this process, in no particular order,
they were liners barrel diameter bored to large, ineterference of the liners and it was brazed rather than welded, the first liner was shrunk in by me to 0.0023 thou, it was very accurate, It kept taking 0.005 ought the boore each time we ran it, it distroyed the inners just blipping the throttle, especially if I opened the throttle quickly - eventually we had a reputable company make and fit a new liner out of more convetional material, this time it was even worse, taking at least 0.010thou out of the bore without load, what a mess, I tried so many things to cure this, cost a fortune every time we ran it (ne piston big end bearings ) eventually I decided to take the liner back out, we found the problem, the liner was tapered 0.003 thou but also the bore was also tapered the other way, meaning a 0.003 thoug interferesnce one end and a 0.007 thou the other, this was corrected, untill we eventually found a size for size or slight clearence of 0.001 to half a thou clearence 0.0005 was best, we cured the distortion, now it would run but I could not run a close piston clearence, reasons for this was each time we made a liner or took it out I kept increasing the liner thickness, trying to reduce the distortion, ! the liner wall thickness went from 4mm to almost 8mm, this made the main barrel week, and caused cold siezures, a lot of effort, and to no avail, I always believed there was enough tallent in the club to help,
the information was never forthcomming and besides we never had a forum like this then, I'm sure they would have been solved.

Mick

It is exactly as I said -- a newcomer would surely be put off unless like Dan of Kent he has access to machines and welding equipment or knows a kind-hearted geezer who has access to ... or owns such equipment, and does all this sort of thing with a degree of skill and sympathy ....

When I built my 500cc & 250cc grasstrack specials I had everything I needed at Walthamstow Tech and my good luck included an old geezer, Mr Brown of the local garage, who had a fabulous MachineShop who boasted he could rivet a broken egg-shell back together.
Such a man of enormous experience is a Marvel --it needed patience***, of course, I´d have to wait until I knew he was free and I "drop in" on him and he was always good for a chat and then I´d say, "Mr Brown, have you ever come across this sort of machining problem...?" and whilst I am trying to explain he´d rattle out at me saying, "Where is it then? get it out." ,

*** patience is essential in race-bike preparation. I was over in Milan when my Son Slick was working for Foggy and I put in a couple of hours on a mo-ped an Italian kid brought in whilst Slick was in conference Valentino Ferrari and got a right ripping off from Slick later. That was for leaving his tools all over the bench. "Disgusting!" he snapped at his poor old Dad, "I´ll bet you haven´t a clue where the circlip pliers are -- nor the penetrating oil...??"
Of course, he was absolutely right -- one thing to put you off that feeling of being-on-top-of-the-job is to not know where that tool is -- which you want to use next.

Very boring --- Yaaawwwwnnnn!

Yes Mick your correct I made a mistake putting it between the "quote marks" rather than after them,

I have corrected this now, and removed it.

my apoligies to Mick - I do hope this has not offended you

Im not sure what I did but its corrected now.

Kind regards Derek

hi some more photot,s you may find of interest.

short stroke motor 50x56.5mm ready to go back into the frame.

derek just found this "wencon exhaust repair kit" google this and theres a pdf file giving spec ... may be worth a try....

many thanks Nobby 1300c (2400F) sounds perfect, resists direct flame, and it can be ground.

wencon exhaust repair.

Derek

Hi all just thought I would put an update on our status quo.

I have not had much time of late as i have been very busy doing some late and "all night" carpentry work, installing floors and stairs for a very worthy cause. I had to borrow the saws and power tools as when I turned my bench saw on it caught fire,? its been so long since its been used, never had that trouble with my Bantam, Anyone wishing to look in more detail about my life changing experience doing this, it was a very worthy cause, could either wait for the TV program BBC DIY SOS to come or check out some information at Dijon Home & Flooring or my face book page to find out more (a truly life changing experience).

anyway back to normal now, so on with the bikes, I need a small amount of welding done on the crankcases around the timing side drive and layshaft bearing housings, this has two small cracks between the bores if anyone can help

The guy who use to do my alloy welding has sadly passed away !

I also had time to drop in at Rex's place to pic up some crank shims, I needed for our 175cc engine, and to catch up on what he is doing on his bikes with others.

it was a very interesting morning "Rex" makes a lot of spares for bantams various gearbox parts for only 4 speeders, also alloy cylinders / pistons, clutch plates / drive plates and a lot more, I have to say. I'm not sure he still makes ignitions as he has retired, or so he tells me ?, just can not see him in retirement.

I managed to pop into a friend who has given me some very interesting photo's, George has reverted to his interest in photo's, I was hopping to get him to reveal some more info on his past, and do some other things for us but i think he has just gone past it with his age, we will see.

I also found time to go along to the classic bike show and to catch up with Alan and Mike doing there bit for Bantam racing, This show was a bit of a disappointment, not a patch on the stafford show, for me is 10 to 20 x bigger, if you want to increase the grids this for me is where we need to have a presence 'Mike!! ref our discussion - my offer still stands, and did they contact you, I feel others should/could be persuaded to help if not enough time doing sorting organising, or wish the hassle that goes with these things, ask for help/support - !!!!!!!!!!!!!!


regards Derek

Hi Derek i'll check out your BBC DIY SOS ....

I hope Rex hasn't retired as I get a bit of stuff from him.. as he is very reasonable with his prices.

Try facebook Motorcycle Racing Nostalia - I tagged you in a pic the other day derek!

Shows - well i thought Newark was a success - Alan and I talked to loads of folk and gave out lots
of flyers... I next show Alan and I are at is the Festival of 1000 Bikes, which is a show I really enjoy.
The problem here appears to be bantam racers are not interested in going... Which is fair enough you
cannot make people go to places they don't want to go to... Any help at 1000 bikes - bring it on...
Derek can you help at 1000 bikes ? Stafford (Oct) any help anyone? Derek i'll pm you.

Mike

mjpowell wrote:

Hi Derek i'll check out your BBC DIY SOS ....

I hope Rex hasn't retired as I get a bit of stuff from him.. as he is very reasonable with his prices.

Try facebook Motorcycle Racing Nostalia - I tagged you in a pic the other day derek!

Shows - well i thought Newark was a success - Alan and I talked to loads of folk and gave out lots
of flyers... I next show Alan and I are at is the Festival of 1000 Bikes, which is a show I really enjoy.
The problem here appears to be bantam racers are not interested in going... Which is fair enough you
cannot make people go to places they don't want to go to... Any help at 1000 bikes - bring it on...
Derek can you help at 1000 bikes ? Stafford (Oct) any help anyone? Derek i'll pm you.

Mike

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Hi Mike

Shows It would be good if you could get others to support you by bringing their bikes and helping organise/setup! too,

And No I think you miss-understand my comments, I think it was good for Bantams, just feel you need a much bigger audience/presence, you have people interested so its was good.

i did not mean it was not a success, how do i know, i was only there for the last hour. just thought the stafford would be better.

Rex you got special prices then LOL. but yes he's cheap, nothing it always cheap enough.

Fest of 1000 bikes, not sure I would really like to go but not sure I will be able or can afford the time.

BBC !- We will see, keep you posted, looks like I may become a regular, but only in the background, its all very rewarding.

regards Derek