a new member and new builder plus progress so far

thanks ted, i've made another top hat bush and bored the clutch centre dia to 22mm as this had
wear in it, and had a good look at the roller bush i fitted and changed my mind and made a new
bronze thrust, it spins up with the air line on it and thin oil, so think i'll leave it alone , got to make a
clutch compressor today,

i'll be able to pop along to the pub soon although i've got a lot on in the evenings at home lately d.i.y , i'll sling the bike in the van and bring it along too,

i'm on the look out for a second hand fairing if anyones got one?.

I do have a Jimmy fairing the same style that scuty & Mike P use that has never been on a bike & it is for sale. Make sure the clutch is quite lose as they do tend to go tight when hot. The most iportant thing is to remember DIY stands for DON'T INVOLVE YOURSELF.

Fairing ref type Ian and Snowy have a Scutty fairings, I have a Powell fairing. They are very different.

Dan I only run 6 clutch springs, then when it starts to slip- 7 etc... Sure i've posted on it in the last 6 months.

I did not know there was that much diferance I can send photos if anyone is interested.

i picture of the fairing would help ted as i'm not really sure what it looks like, i was hoping to get
a launchbury style one, or maybe the vic camp ducati type, these have nice open bottom sections and i figured it'll help to cooling a fair bit.

dansofield 550
I have a Launchbury fairing you are welcome to, it's one made by Jimmy, I had intended to fit it to JS2 but after a little
chopping about I came to the conclusion it would not work. Top half can be used as is as could the bottom half but a bit
of glassing up would bring it up to scratch. If your interested call me on 020 8644 3968 I live in Cheam Surrey.
Regards.
Les.

thanks for the offer les , much appreciated, a friend has told of a fairing he has had knocking about, he didn't knpw what it was , but if no good i may well take you up on the offer, have you a price in mind?

on a different matter, are the paper gaskets any good for a race engine, namely the cylinder base and head?

should i make ali ones? or maybe copper.


thanks dan

Hi Dan as I said you are welcome to it, I would rather you have it than have it sit in my shed doing nothing,if you want it
it's yours,I also have a new screen to fit, to you £20, thats what I paid.
Regards.
Les.

Hi Dan

The cylinder head should not need a gasket - metal to metal is fine as long as the barrel surface is square to the bore, the studs pull down evenly and both surfaces are good.

If you are getting the top of the barrel machined then take the opportunity to make a small spigot on the barrel that goes out to the stud holes and a corresponding recess in the head. This will ensure the head is always located in exactly the same position, make the squish band concentric with the barrel and increase the surface pressure between the barrel and head giving a better seal.

Between the barrel and crankcase a paper gasket around 4 to 12 thou would be good. You could go a bit thicker if you have to in order to set the squish clearance.

Mick

thats amazing , thanks i'd love it, would you like me to collect from you one weekend?

also , i've not been to cheam before , and just had a look at the maps and notice parts of it are in the low emission zone, if you would pm me your address we'll work something out between us about collecting , if your inside i'll use the wifes car as my van is too old to enter the zone by 6months !
many thanks dan

thanks mike, i've machined the top of the barrel square, i made a tool bit with a 103mm rad(to match the wiseco piston)and turned the cylinder head squish , this i thought i'd start at 30 thou turned out of the head, might need to make this more as i was thinking i'd need a head gasket that would increase it to 40 thou .

i'll have a look to see if i've enough metal to make a location ,

Hi Dan

the usual recommendation for squish clearance is 30 to 40 thou.

A simple way to check is by laying a strip of soft solder across the piston crown, putting the head back on and turning the engine over tdc.

I wouldn't like to go less than .030 but a small adjustment can be made with the base joint without upsetting the port timings too much.

Mick

Dan, phone me on that number I'll give you directions.
Les.

hello les , great to meet you last week ,and thank you once again for the incredible generosity by way of giving the fairing to me, i really am chuffed .i smoothed out some of the cut outs here and there and think a little extra air over the engine can't be bad so i'll leave them be.

had a little go at fitting it this week , its kind of held in place by some brackets here and there, but looks the business .will be making backets for real next week.

got the engine in and built up, squish is set at 41 thou,

i got the parts from you in the post today also, all fine no damage from the postie, will be making a start on them monday.

just wondered if a breather on the clutch side would be a good idea?
poss vented into a bottle, maybe this is common but not seen or read it in other posts.

Hi Dan

a few folk put a breather in the clutch cover. It helps to stop oil finding its way out of the sleeve gear as there is no oil seal on the mainshaft only a left handed groove that is intended to scrape excess oil back into the gearbox but it doesn't work so well if the oil is smoking hot after thrashing the clutch!

for an example, see here -

https://bsabantamracing.editboard.com/t746-mike-powell-s-125-engine

Like the fairing !

Mick

I read with interest your comment about the fairing specifically the air flow, we have George Todd's ear at the moment (the man who developed this fairing) why dont you ask him on face book for some detailed history on it, and about the importance of those little suttle changes in shape around the toncil area and down the sides. I would like to know it it makes much difference if the lower hals are open at the btm, as many were like this but Freds Bantam at the TT in the old phot's are not, I believe the little features as it comes towards the frame are very critical to direct and set up the air pressure and flow location, and as you say air flow over and around the barrel is critical for a reliable aircooled motor, and does make the difference, we always would gain 500rpm just adding fresh air scoops and the drop off after a few laps was always a lot less, my work on the dyno at the moment has shown us we may have always run with to small a tail pipe, as the temp reading in the engine have gone down and power up, seems we always have a lot to learn.

from what you have said I deduct Lez has possible noted the importance of the fairing features to you, I managed to get a new one last year absolutly snip and beautifully manufacturered, but sadly the toncil area had been cut out, I have tried to take a mold off an older one to make a repair piece but this will have to wait to a little later.

Your bike is really comming on, and i think it looks great, very goo just love the fairing, never seemed to amaze me how generiouse people who race Bantams are, right back in the day when I first started it was always like this, its either given with good feelings of support or swopped, when money does change hands it was always never the worth, this appears to be changing with some of the quotes I have seen latley.

anyway l like the rear sub frame very neat.



makes sure you ask george sure we would all like to know the history,

regards Derek

Hi Derek! re your dyno test work -- are you using fans to simulate track cooling air on the dyno?

For optimum air flow thro´ and around the engine I´d say most fairings are the wrong shape! Relative OPTIMUM cooling airflow, I mean.
Can you instal and instrument anemometers on your engine dyno test??

hi john no I use an electric fan to aid cooling but do not do long runs, I have it at home, its my new "toy"

on the anometer NO

but if your challenging if air scoops work they do but not on the dyno -

But I have asked George about the origin of the fairing and its development, I hope to get an answer soon.

regds

Derek

hello derek.

interesting about the air flow topic, i had seen it mentioned on her before that a lot of work was done to the shape
of these type of fairing,
one thing i have in mind is the original bikes with these fairings had low exhausts and the cut out does
go a long way down,and indeed bulge's out on the offside . mine however is all above and next to the cylinder barrel, thus giving me the idea and thoughts that
i'd leave the holes in the leading edge of the lower fairing as they( just by chance) happen to be right in line. les's bike is a water
cooled 125 and the cut out were for the rad in case you wondered why they were there in the first place.

interesting also about the 500 rpm drop off you mention, is this from a long time ago or on recent running? and do you mean
that it wouldn't physically rev any higher? i.e. expansion of piston in my layman's guessing stab in the dark way!

i've wondered about making a scoop for the carb to direct air form the outside of the fairing,not an airbox sealed and pressurized ,just a scoop making a cool air supply constantly .. is this not done? or been done or not worth the effort?

hi there

air flow:- I have asked George about this, he has posted a photo of Freds fairing inner on his facebook page, i hope he will elaborate on this.

500 rpm drop off - ?, yes without two air scoops my bike would lose an edge / or its edge after just a few laps, and about 500 rpm after a very short period - with two air scopps positioned correctly, the edge loss was delayed a further two or three lapps and with no loss of any rpm's. since my return I have a combustion chamber the size of a cup of tea, but this is slowly changing becomming smaller. We have had a similar issue recently, but its nothing to do with anything other than faulty manufacture - lack of checking on tail pipe inner diameter, and the silencer inner diameter too.

On my return 2010, and due to comitments in 2011 - the Bike changed very little, but more or less its now getting back to almost the same spec as it was when i solid it at the end of the 90 season, when I first built it, after purchasing it back, I had detuned it considerably, untill I was happy with the exhaust, its not far away in its current state, other than a few adjustments, once I get it back to it's reliable ish state, I intend to turn my attention to other things.

one other point - I remember Martin Nash-'D-villias telling me he tested the air flow scoops on his Fairing with a water hose pipe from the front, a sound method identifying where air flow went from the fairing scoops, (on his none Todd fairing). so air flow is not to be ignored and is very important on an air cooled motor.

regds

Derek

I was only suggesting that modern fairings MIGHT be wrongly shaped for OPTIMUM air cooling -- in terms of the front wheel & forks interrupting airflow to the fairing holes...

The nearly `perfect´ streamling was with the front wheel enclosed in a streamlined nose shape PLUS a tail piece behind the seat and rider -- which, as we all know, was banned. The modern fairings do work -- no doubt about that -- but I have doubts about whether the level of their full effectiveness has been reached relative air-cooled engines.

Consider that the air does not have a smooth flow around the wheel and forks to the fairing, then after it has passed thro´ the cutouts there is a sudden expansion space where the air velocity surely drops and the airflow is then also choked by the rider´s legs.... Or, am I wrong, and this `choking´ of air-flow is advantageous to air-cooling?? As I understand it the air-cooling-fins are designed to be less in number, widely spaced for low thermal load and thin and more numerous for higher performance engines.

I just wondered about how much development work on this aspect has been done during the life of The Bantam Race Machine with several excellent heads being invented and put to good use over the years... ???

Perhaps the increasing of air-flow around the head and barrel -- which is possible -- with the review of finning in mind MIGHT be worthwhile??

Hi John not able to follow you but here is the development you say as never happened, anyway hope other find it useful it was kindly sent to me with some other stuff ref fairing discussions hope this is the right place for it.

Derek - This was all so long ago, I'm hard pushed now to recall the history. Basically, there's no mystery about the fairing on the bike that Fred rode in the TT, and other national events. It was a continual development story over many long nights in the workshop at the back of Fred’s Raynes Park shop…

The picture showing Fred winning on #34 at Castle Combe was the initial version, a stock fairing from a racing goodies firm somewhere in the UK. You can see in the picture with Mole Benn, Roy Bacon and Fred that they all used this basic fairing…

We soon figured the airflow could be improved by covering underneath the engine with sheet aluminum, and this can be seen in the 1963 TT picture with Fred on #56.
The next development was an all metal version made by a workshop friend (Fred had so many contacts in London) seen in the Baluagh bridge picture (with #44).

This became the model for fiberglass moulded version, which had a specially shaped entrance to the engine area (or tonsil as you call it) to smooth and concentrate air-flow over the cylinder. Instead of a sharp edge to the cut-away "tonsil", the form doubled back to make a classic air intake (see air intake pic #2).
Note also the shape under the top section to improve down flow onto the engine.

All this came out of my background in aircraft engines, but it was nothing more than logical thinking and the old adage "if it looks right…." Regarding wind tunnel tests, I have a faint recollection of there being something planned, but I don't think they ever came to fruition…!!!!!!!!!!!.

George Todd

Hi George -- I never said the development of air-flow to fin dimensions -- area, number and thickness etc -- didn´t happen --

-- it was that I NEVER SAW anything of it...

...and I do agree if a thing looks right then it probably is right -- calcs and measurements sometimes prove it conclusively ....

I am in my dotage where I am looking back at all THE THINGS I NEVER DID AND SHOULD HAVE DONE whilst actually racing a Bantam (and being a sort of stand-in, layabout chairman for BRC) where I only did the frame & cycle bits.

My excuse (poor one really!) was that I was exceedingly busy at the time. Domesticity in the shape of a two kid family, house and two car maintenance plus being on call to Simms Motor Units over weekends didn´t leave much time for the BRC -- however I did have a cadmium-plated (by Leyland Motors Ltd...) Bantam frame out of it....

I am also not criticising the fairings as they exist today. I know a lot of engineering effort has gone into their existence -- I am saying that there MIGHT be a better way of directing the air flow INSIDE the fairing whereby the air-flow-velocity is increased in much the similar fashion to the Mitchinson oil-coolers on the Spitfire uin WW2...

Air-cooling being Direct cooling, where typically the temperature difference is 180°c should be more efficient than water cooling where, correspondingly, temperature difference is 80°c.

Just mumbling away to myself here -- sorry if upsets anyone´s
personal feelings....

Nice to hear from you George!

Go well and keep well,***

Cheers!

JayBee for John-Boy! (Much younger, of course!!)

***Malawian farewell which I like using on fellow Europeans.

I have in my shed the original Fred fairing that Fred had made in the 60s made from alloy that the original mould was taken from the top half is original but the bottom was shortened in the 70s and modified to fit our Maico,s. Fred told me the basic shape came Tarquino Provini,s 250 Morini single narrowly beaten for the world champs by i beleave Jim Redmans works 4 cylinder Honda . These fairings certainly work in the 73tt Richard Stevens on a Maico with standard fairing did 104mph through the speed trap i rode the same bike in the 74tt but fitted with a fred fairng did 112mph and in the same tt Tony Jones on his Bantam did 106mph.
Bill

I just wondered if there is a computer simulation programme for fairings, as there is for engine efficiency, with which we could compare several fairings? As Mick Potter said, the particular rider should be included as part of the streamlining exercise so the simulation would have to include elbows and that bulk some of us unfortunately had (and maybe still have)....

There IS NO DOUBT that the various fairings we see in the pits these days DO WORK -- it is HOW WELL? And HOW WELL according to the Stature of the rider ??

The Jaque (spelling might be `Jake´) fairing I fitted to Icarus-1 was said to work well in the IoM on a 250 BSA twin in the sixties and I think there were times I was sure that it was "doing something". That of course was purely subjective which supports the above that I might not have chosen the right `skirt´ to suit my bulk.

What I was referring to earlier -- which was a digression from Plunger Rear Springing on a Bantam -- was "Dustbin" fairings as on Works Guzzis, ridden by Bill Lomas & Dickie Dale -- and, of course by riders like Ray Amm on the Kneeler Norton.

The picture, that didn´t work, just about showed the plunger rear end of the Walsh Bantam in the Guzzi Dustbin streamlining which covers the front wheel entirely.

That was unfortunately & mistakenly taken as my criticism of current fairings. I was looking at the ultimate in streamlining -- which is the Dustbin-with-tail -- as a sort of Standard to compare other streamlining fairings with ....

Cheers!

For JB