returning to bantam racing

Hi Derek ,
How did i guess the long rod , with a 54 stroke and bad flow reversal that means low case compression and that means a long
rod! When i first began with Bantams we all used the 58 stroke and 125 rod , after each meeting i cleaned the barrel and
the transfer ducts always had a black, sooty and oily deposit in them . This was of course combustion residue , although at the
time i was ignorant of this , when it was explained to me the penny dropped ! Some while later i built a 58 stroker with a 116
long Bultaco rod , and , the problem was all but eliminated ! The only major difference between the two engines was cc volume.
Acceleration of the piston away from tdc and rod angularity play a role here also , but if you don`t want to plough through
" Heavy Crankshaft" again we`ll ignore it !

Carb size and tranfer port area correlation is another candidate for Room 101 , i think you might have picked up this idea from
pages of the old club magazines , in Colin`s technical articles . It is a concept i give no credence to, and, if you think seriously
about it can only be an extreme exception to any rule .

Don`t move your barrel , sounds too risky , do you have any scope to raise the ex height and/or widen it , maybe even adjust
the corner radius , any thing to achieve a touch more area and improve blowdown time area . Depending on your transfer timing
there maybe scope also to actually drop the height this will achieve a simillar effect , combine them all and some improvement
could be achieved . Or , being extreme , junk the long rod !


Good job with the photos , it`s amazing what a little judicious , controlling guidance to a gas stream can do !

If you want to PM me with specific details, to be kept confidential, feel free ,do my best to help ?

Catch you all again , Trevor

Hi Trevor
Many thanks for that feed back, yes ducts, I;m really thinking a feeling that transfers is where the power is, not just the open or time area, but much more inportant the direction and angle they entre the cylinder at, but the basic direction towards the rear of the cylinder from port joint face moving to the rear of the cylinder! is so important, the inner faces seem to have more effect on the Torque curve above 6000 is this correct observation.

I noticed my ducts are very tapered from the face nearest to the exhust port to the window but the other face seemd more of less straight, up with cylinder axsis. !

the rear transfer port comes in at around 44/45deg, i beloeve this i better for maximum power.

the two std ports as you can see where fettled and balanced by DAD in about 1962 to 63, they open within a thou of each other, he spent many hours with riller file and a dial gauge and block, and measureing burret. one loks slightly different angle at the base but they are so accuratly matched I have tried many times to duplicate this, and can not get them as close to what he achieved.

The rear tranfer port adds quite a lot of area, and made a huge difference to performance after we added the reed , this was somthing Pete adviced a number of people on while we were talking in the paddock in about 88, after my return from a few years away,
what is your take on this Port as when I have tried to widen this we seem to lose so much power ! I have it packerd with devcon to reduce its width internally, Not sure why the hole in the rear skirt rither just to aid cooling I think !! please comment on this. !

based on the experiments I have thus done do far i'm very happy with the assitance and improvments we are getting, .

we feel we may have gone a little to big with the head volume, we feel the CR ratio needs increasing, I have machined two heads ready for testing, Ihave from the coments left the corners very sharpe to promote the flow explined in the aprilia schemes for promoting turbulence up in the head, so this will be interesting as even with such a low comp ratio, we already have in improvment in bioth torque
the power, but ! above 9700 to 9800 it starts or seems to be slowing and starts to fall away (ie the curve slows considerably), why do you think this is / more to the point what figures should I give you, (Ithink the breathing is not as good as it could be at this point its like it goes into a hole) what infor do you need, that will enable you to point me in the correct diffection,again, and if its OK with you I really do wish to have this in the open so other can learn especially the new guys, I,m really not concerned with confiditial, unless you wish to keep what you tell me so !

I would really like to see 16/20 bantams all the same of similar speed its better for our future ! no doubt there will always be a front runniner but its not healthy for the class if he is too far in front - people lose heart and can tend to give up. so please post your support for me and others to read.

On the 175cc bant Im puttingtogether, "I loaded a port trace of it, I have been working on it also, I was concerned the exhaust port was too wide, "it is" the wrong shape for a TZ 350 piston - its too square again uncovering the exh port at BDC. because of this, I need a square skirt piston, if anyone can help with suggestions on this, please"

I have been looking at American Ebay and the skidoo pistons - "they look very nice", anyone comment of this or tried them. ?

I will PM you Trevor, "we dont want these London boys knowing all the secrets do we"

Kind regards Derek

Before and after shots (information curtesy of Trevor Amos) it seized on the dyno after this, while we have a graph showing huge increast in torque that was around 9ftlbs it was up to 13.5 before we seized it we made an cardinal error so excited about the increase in power you could tell as soo as we put it under load, the engine was pulling much stronger, but we forgot to check the lamda? with all the excitment of our new found knowledge and information all from this webb site, we never had the chance to check the power while our initial run showed no increse in top end what it did show was a 40% increase in torque yes "four zero"!!!!!!!!! i can not wait to repair this thing and get it on the track, we have heared all sorts or things bikes never produce what they do on the dyno on the track because of x/y/z but surley this thing is producing more torque and 3hp than it was before we started.

please see pictures below Ihave dressed the barrel but you should be agle to see the minor changes bring about this improvments, unimaginable that such small changes can do!!!!!

I have a btm end to rebuild and a new piston and rings to sort out, we are ging to try and find a proper piston that has a longer skirt and re peg it so it misses the top of the inlet port.

before see previouse pages not the top edge of the exhaust port - the timing has not been touched nor has the centre of the port, but the courners have been blended with 4mm radius (8mm brinding wheel) then blended to the top edge radii -there is s slip on the right side edge but we left this

and picture after blending
https://2img.net/h/i1022.photobucket.com/albums/af348/derekjbetts/004.jpg

can any one tell the difference.?

after grinding and no change in timing


before look at corner radii



ref it seizing we actually saw it but it seized so quickly we neve had time to react quick enough / clearly these veru minor details have bought about an improvment in the scavenging and breathing so the trapped charge has increased to what.! who knows by how much.

please feel free to comment as no coment is negative any coment no matter how it sounds is valid as its an opinion and all opinions count no matter how they sound - weight for instance! lol

Trevor on the
stroke rod I have a long stroke crank would it have the same effect if I reverted to a long stroke with this barrel as this would be easier than converting it to a shorter Rod, as the cases are standard nothing machined of the top face of the crancase barrel joint, it was our way of building a short stroke engine back in the day( 32 years ago this year)!

regards Derek

regards Derek

one more "important point" for Trevor !

No sign of the disturbance with it attacking the materials used to shape the inner transfer ducts like it was ! before your comments/information and assistance on here !! even though I have used the same material to packing and shaping / blending the inner walls of the transfer ducts, over painted with araldite see in the upper shot right transfer duct. ????

although there is still some signs of discoloured oily residue in the ducts and botom half of the motor. ??

regards Derek

so new fins on the top end well slightly modified as shrunk on as before, better intereference over the years standing in had curroded to a point they were no touching the barrel in a few plances, now its ok aagain


with a little help from George Todd himself from photos and information set to me



moved :-






New cylinder head, radial fins according to the aero engine boys fins on fins dont work very well so radials like this but even better see if you can see the fins are the opposit way round, been looking for one of these for 20 years well 20 racing years, such a pain as the fins are tapperd thre ways thicker at the outer edges, John Bass please comment explain theory I forgot what Iwas told about this. but it should run a fair bit cooler for the same air flow. !!







please feel free to comment. you can see my metal working/bashing skills have wained a bit!!!!!!!!!!
it will be cleaned up once we find a working solution as its created two other issues can you see what these are.

finishing off for John Bass

yes Mira she is very big and blustery lady "birtha 2"

But very good fun for a suanday morning bash to leicester.

"seems I have been holding back" this is not the case john I tell every thing I know, as much as I dair, trying not to create other issues.

The result and knowledge gleemed says we have some holes to fill in, (forks leg holes are all too big, look at Mike Powells they are just big enough, we used carboard and tape, what a difference this makes to the pressure and air flow to the head/ barrel and crancases eeven the under side is better cooled as it increases the air flow rate from the fairing, all this and it was even an improvments on cooling also aided aero dynamic flow as the lower pressure wave behind the bike was not as low as more air was flowing through the bike than before,!! if anyone understands this tell me as my head hurts after last week. !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

we now have some holes to drill and a small hump to make - over the top of the head the air flow is not going where it should be apparently an open fairing at the btm (makes a masive difference (you should all be filling this area in straight away", or you may as well not have a fairing, why do you think I been running without the Btm half, one!! it performes better.

what I do Know is as the air flow or pressure is too low! as the btm of the fairing is open so letting the air and pressure out as I understand it!!
(also the hot air from the pipe) but a lot of cool air is not beeing ducted to where it should be, We found this out with a bodge using cardboard, and some masking tape by closing in the btm of the fairing and then "get this" ---------- we used the end of a 2ltr empty bottle of plastic, then over taped it to creat a bow wave form, on the lower front fairing edge, just like the new F1 Winglits I think it looks to ugly kind of like Mikes new fairing that goes over the front wheel, (sorry MIKE JUST AN EXAMPLE) it looked too moden.

I will be removing this, but this guy( who it a real boffin I assume like you john) managed to increas the air flow over the head at the same time as the air pressure in whole regon of the area at the rear of the front wheel and through the fairing, althrough the whole bike fairing, looks a mess (the jet engine duct as Gearge Todd called it see his photo's), interestingly - seems tall ships have them under water, they creat less drag!!! but it looks an awful bloody mess, all taped up, you can not see this in the photo's, you can be sure DAD will soon be busy in retirment beating the hell out of thin alloy plate, I think we just have time to make somthing operational for the first meeting, fingers crossed.


keep you posted. regards Derek

one other point we have to move the coil

for better "IN" - air "flow" or is it presure.

Any ideas anyone!!!!!

I use to put the coil up forwards under the tank, above cylinder head on down tube makes fro a nice short lead. its a real pain as we can not get the barrel of without having to remove the coil from here, seems we need to really try hard come up with good solution to install in ana area not in the way what with all these, temp gauges wires and coils being moved

but I copied Toms idea after a number of years of moving the coil to the front down tube, and next to the ignition, this is not the best place either!.

anyway like John said too many changes "to many" "to soon".

so yes the "coil" is to be moved.

regards Derek

You sounded quite enthused Derek -- and the idea of a naked bottom half is certainly appealing.

What I was getting at about ducts was that if the air passage narrows by a hot place it first speeds up the air by the narrowing of the passage and then as the air heats up its expansion speeds it up still further. Can take quite a bit of experimental time getting the dimensions right. I mentioned it before -- it was how the Spitfire´s oil coolers were made smaller and more efficient than those used on the Hurricane. The idea has also been used in what is called "Ejector Cooling" using the heat of the exhaust pipe to do much the same as above....

But ignore that -- I don´t want to be responsible for you spending all your time on development and never getting out onto the race track.

Point I made earlier -- which was jumped upon most violently.... -- was that a thin legged rider when well tucked in behind a clip-on (handllebar) fairing with a domed nose for the number plate COULD give as low a Drag Factor as SOME of the full fairings I have seen recently. Any flat plate portion -- no matter how small -- when square on to the airflow is going to reduce the streamlining´s efficiency (Ned mentioned the LE´s screen) and one fairing I have seen recently has a curved portion, admitted with holes for air to get to the engine , such that it is like half a parachute being dragged along. Somewhat like so --> .... "<---) " only tilted forward at the top. And some pictures of riders in action show half of the riders´ legs sticking out beyond the fairing edge and then there are elbows and shoulders that never get properly tucked in -- so again I ask -- are some of tham worth the bother...???

OK! So I expect to get another hammering...! OK! So I am anti fairings --

-- NOT TOTALLY!! I´d like to see a Naked, LowCost Bantam Class for Newcomers to get back to the original concept of Racing-On-The-Cheap and the really well made, well developed Pukha Racer that is the Racing Bantam worthy of airing to the public.

YEAH! I have said all that before -- IT MEANS, I MEAN WHAT I SAY!!!

Cheers!

Hi all,
I originally did this post as a PM to Derek but he asked if i would offer it for general consumption in here ,so , with a few additions ,
here goes !

If it was my engine i would not hesitate but go for the shorter rod , perhaps even go the whole hog , and plumb for 110mm ctrs ,
i know it means a lot of engineering work but the rewards will far out weigh the effort . Contrary to popular thinking the Bantam
engine still has to rely on crankcase pumping to move and transfer the weight of gas needed for good power throughout the
effective rev range . If you look at the gearing graph i posted it shows very clearly the rev drop from first to second gear, low
revs imply low value pressure differentials and skewed pipe tuning effects . This means the exhaust diffuser has a limmited ability
to shift fresh gas to the cylinder , but the combined efforts of the crankcase and pipe can get the job done , and the power band
is broader for it ! All of this is a consequence of having just three gears to play with , add two or three more ratios and the problem
just goes away .

Something that is not often appreciated , is , that fresh charge trasfered to the combustion chamber , which has been subjected to
serious blow back , as is the case with your 125 rod , will eventually deliver mixture which is much hotter , and therfore less dense ,
will be far less pure and , will raise overall combustion temperatures , when left unchecked detonation can result ! If comencement of
actual transfer flow into the cylinder is delayed by blow back , even by a few degrees of crank rotation , then , the total time available
for a complete transfer cycle is similarly reduced , and again , power is compromised .

Try to visualise transfer ducts as a diffuser, also try to think of them as the frustum of a cone , both have a regular and constant taper
and you get some idea of the required area change from , crankcase to cylinder interface . Now , of course , the ducts are essentially
rectangular, but i`m sure you get the picture . If you have mould plugs of the of the ducts , cut them across at regular intervals and
calculate the cross section area and determine the rate of taper and area change , you can then adjust the duct shape to achieve a
more favourable profile , it`s a fiddly task but well worth it ! The other reason for taking moulds is to measure inner and outer radii ,
of the two , the outer is of lesser importance , a nice continuous exponential curve works well , the inner radius is very important , it
should track the outer but be as large as possible to avoid flow detatchment , turbulence kills flow and reduces mass delivery .
Duct length has a roll to play here also , as, long gas columns respond less quickly when the port opens !

Fundamental to all of this is the inescapable fact , that , only pressure differences move gas around the engine and ultimately the
trapping efficiency determines the quantity of clean , combustable charge that is in the cylinder in the closed cycle !

Getting back to your transfers , the area ratio between barrel entrance and the cylinder port needs to be in range of 1.2-1.5 this
is not critical but a big duct volume at low engine rpm will flow less well because the driving pressure is low .
One more small point , tight corners at the barrel entrance will be subject to friction and boundry layer problems where local flow
could well slow right down , and , lead to further charge loss .

Taking an overall perspective , if Delivery Ratio is high , and the transfer streams entering the cylinder do an efficient job of clearing
unwanted residuals away and charge can remain in the cylinder then the Scavenging Ratio will be high , and , if your ex pipe works as
it should the Trapping efficiency will be way up and lots of power will be available !
The in-cylinder flow regime hasn`t been touched on but that can wait for another day .

As a final paragraph , i picked the following up from an SAE paper a few years ago but i didn`t give it much regard then , but on
re-reading it a couple of weeks ago , it struck a chord . The engine illustrated is a 65cc industrial type , as used in chainsaws and
brush cutters etc , not very powerfull but quite revvy . The context is " Intake system Behavior ".
I quote--" In terms of the mass of air already in the crankcase , the entering quantity is quite small. Put crudely the DR value is 0.5,
or about 32.5cc in volume terms for a 65cc engine . The crankcase compression ratio is 1.5 , so it`s maximum volume is 195cc ,
Therefore the entering volume is only 17% of the total in residence " ! Substitute your own Bantam numbers , you might have a
bit of a supprise !

Cheers for now , hope it helps someone Trevor

Hi Trevor
many thanks for this and your support,

I see you left it all in, many thanks, I am absolutly sure this type of information will bring encouragement to those who see it all as ! just too complicated when with a little knowledge it can be just the littlest things that really matter /rod ratio to stroke and inner transfer radii and the ducts worked on with the correct knowledge, all done with moulds a grinder and some files, ots of effort and just time.

Im absolutly sure this will be a big help to others, its great we have a few willing to share such information.

Please check out my pictures of my dads motas work! we have no printer but I feel a photo is better as proof, some readings are are from our current/old engine, the others are an engine in progress based on my old water cooled crank reed engine project.

we may need some direction setting up the numbers properly do we set combustion efficiency, or is it generated from the numbers does 0.8 sound correct, we feel there may be some issue as they such high numbers, extremly surprising results on torque and power but almost exactly what we have on mine current "well" its actually comming out slightly higher on the motas program than we have on the dyno.

For JB "yes yes" I will get to the track, the track is where it's AT

very best regards Derek

P.S Trevor see these photo's are you talking about this radii as the enter the duct, or as they enter the barrel or both

PHOTO Entrance to duct !


PHOTO Duct entrance to barrel !

motas prints for your viewing

please feel free to comment.

some from dads new engine based on our old crank reed engine and some on our current engine.

Just chatting to Tom Miller about Ports and inlest and exhausts this morning, he has some other advice on this his theory is obviously back up with just as much history, But I have to say it sounds so much simpler when some one is actually taking you through it "step by step" rather than reading it, and trying to disyfer what has been written.

I had Asked ALAN Brown too and who would like to come but he's not sure if he can make it, we do hope so AL"

Both Tom AND mICK sCUTT have both agreed to they will be comming, the object is for these guys to offer advice and technical assistance, at the midlands Bantam racers bash, just to explain in simpler detail with some feely touch items to help, Tom has confirmed today and said he's comming with some Engine or a few bits and pieces.

sadly Mike can not make it hes cooking sunday luch! atually I can not remeber what he said his "excuse" was. !

What a morning this is going to be, with a few others, the Tea and coffee is on me.

I now longer have Brian Whites telephone as I lost my old mobile dnt have his number written down so, could some one kindly email it to me, as I wish to invite Him and John too, we have to have Brian there.!

So come and joing us for the Midlands Bantam Racers Bash on the 1st April Sunday 2012, at 11.30 to 4.30 on the car park, then inside for chit chat and tea/coffee.

going to bring my other engine that Ihave not had time to sort out as too busy with my son's(eds) bike build, this engine we think has a seized crank or the mains have seived or possiblt a big end, not sure never looked inside since last september, at the second to last cadwell meeting, the idea is I will be timed to strip it, just to see how long it takes and on one of the tables inside, I will remove the clutch and drain the oil out of before I come, first, "but how long will it take" I recon I can do it in about 9 minutes, completely!. Im sure the barrel is an original BSA GT, the liner is new done by Brian white what an excellent Job too, but we will see, it's currently being converted to a reed valve by dad, so we can get an extra port at the rear of it.

to finish off The Second BSA BANTAM RACING BASH, The location is the "The Suger Brook Pub" In Bromsgrove, on the main A38 between the M42 junction 1 and M5 junction 6- come off either mlotorway JUNCTION and just head for Bromsgrove stay on the A38 and the by pass do not go into bromsgrove stay on the A38 BYPASS "IT BY PASSES BROMSGROVE TOWN CENTRE", Its on a small set of traffic lights between two big Islands. so if you pass two reall big islands you have almost sure to have passed it. (you can call me on 07960 878 319 if you get lost, i will answer if Ican hear you with all the noise of running Bantam Racers!)

ALL ARE WELCOME.

We have a real surprise as to who is comming to.!

Hi Derek!

Your first & third Mota Power-Torque curves look upside down!!

Phenomenal performance but I hold myself in check for the moment because I would automatically (please don´t get upset...) check calbration of the dyno -- the wheel´s Rolling Radius for example (with KR73 WM1 it is 11.4/12ft then with Dunlop KR825 it is 11.8/12ft -- this example makes only 3.5% difference (0.95 to 0.9833 respectively) but with some other factor mulitplying it up the %error goes higher ...??)

--I don´t know how such dynos are calibrated but with larger engine dynos, weights are attached to the dyno carcass and the Torque read-out is checked for accuracy over at least three levels of Torque. The speed, of course, is easilly checked by an instrument directly on the engine.

Which brings me to the 3rd Power/Torque -- only goes to 9000 and not 9500 as in the 1st graph?


I hope you don´t think I am being super critical but it was a part of my working life -- suspecting "Excellent Engine Test Results". Leyland once had a super engine up in Lancashire which gave 40horsepower less on a Simms dyno in Finchley.


Cheers!

Hi John they are simulations from Mota's 5 of two engine one is a reality "the lower power item" and the other is my crank reed engine with a new bareel that is not a reality but WIP - the lower power out put on the simulation is the same as what we get of the Dyno, (only just calibrated and new) and it produces about (with in 1/2 hp) the same as it does in the software as it does on the same Dyno,
the other is make believe, the barrel is to be new, like I said WIP.

but you could be correct and the reason why "we are checking things" that we have them corrrect, Both Engines have almost the same settings other than a few critical factors like shorter rod/ 2 more ports , duct shapes are better and volume the pipe is the same!!,

On the read outs with high BHP - yes on revs to 10,000! dad does not know why its producing so much at such low HP that why we have shown it we too think somthing is wrong.! (like I said before, I dont believe in make believe, only the here and now).

but thanks for that John.

regards Derek

Derek! that´s fascinating!

But I temper that statement with the thought that you were on the way to cooking it! Melting it might be more apt!! That second graph shows the rise in degrees F rising rapidly above what appears to be 4,400°F... Was that when it seized??

Point there is that when everything is nearing its hottest limit the engine performes at its best. Were you checking air-fuel ratio as well? What fuel were you using? Safe with 100 octane fuel is rich at 14.5:1 Fuel:Air ratio --- and leaning-off at 16:1 can be done for a quick look at the effect... I am told that engine management systems -- on race bikes -- do this to give a boost to power but I am so out of touch these days I must admit to being relatively ignorant as to how and when this is done....

Keep at it!

Cheers!

Hi John.

Just spotted another item in your last post to me, there is another set up in the graphs loaded showing 3 not 2 as you say, not sure on the other things you talk temp, you clearly understand this.

For sure the reason the other bike seized was exactly, "fuel air ratio" but we never spotted it was the same as on the other graphs.

Although there does not appear to be any drop in torque, only a change in power!, but the temp does come down, 11.0 to 13.0, I have been told,! but bow to your superior knowledge,

we think, compression ratios ignition timing, needs to be tweeked downwards.

Regards.


Derek

Derek ,
Just a few points , the tiny radii shown at the "entrance to duct " photo are what i was refering to , transfer port edges in the bore
should have a minimal chamfer at the top and bottom , to aid passing of the the ring , every where else needs to be no more
that de-burred .This will make the port window resistant to reverse flow -- aero dynamically "dirty" !

With all that ducting around your engine , can you be sure that the high temp air in the engine compartment , and the high heat
flow over the barrel fins and pipe is not pre-heating the carb , and in turn , being sucked into the engine ? If this is happening ,
inlet charge density will drop and internal temperatures will rise , both effects will rob the engine of power , and make carburation
more tricky to get right ! Might be worth sticking a temp probe in there to check whats happening ?

John`s mention of the Hurricane reminds me of a time at Old Warden airfield , during an organised R/C model aircraft flying day,
when the resident, clipped wing, Spitfire pilot asked for model flying to be suspended and to be allowed to take off to fly to Duxford
airfield ! With formalities over , the Spit was fired up and then had just 6mins to get airborn and flying fast enough to get sufficient air
through it`s tiny intakes to aviod overheating and almost certain engine seizure ! As a reward for our co-operation we were all
treated to an impromtue flying display , conducted , i may add , at what must have been an unlawfully low altittude !

Finnally , each of the " imperfections " incured during construction of the ex front pipe will rob the out going ex pulse of energy , the
subsequent returning wave will also be reduced and the power falls , agreed not by much , but , if you lose 1% from 100 sources you
could be in trouble !


Cheers for now , Trevor

Edited 7 hours later:-

Hi Trevor!

At last you mention pipe imperfections which I mentioned ages back. I imagine the bumps and warts and ripples from welding MUST have an effect and at last you say it in positive fashion. Yet I enjoy your comments and see my further argument below concerning ducted-baffled airflow....

Hi Derek!

I just realised I made an awsome mistake in replying to you earlier. Reading too quick and then answering without thinking -- I´m thinking (NOW).

It was when you said there was a high temperature at the 2nd top fin which was odd to you and to me (reading it). I stupidly had in mind an exhaust sticking out of a cylinder head -- á la 4-stroke engines.

You must have been confused when I said bring the exhaust to the upswept mode á la Trials ... I was totally WRONG -- the exhaust on a 2-stroke pokes out way down the barrel. But I might have been partly right in saying that hot-air from the exhaust was heating the barrel -- perhaps, because the air was being directed upwards....

And, as ever, I agree with Trevor - ducting -- and too much ducting -- CAN worsen the situation. This is why I said it needs a lot of experimentation time to get it right: if it is wrong it can be catastrophic. Being I worked on air-cooled diesels for ten years I can vouch for disasters -- so I just hope I have not misled you too far. What we had in our V-8 engine was a thermostatically controlled fan. ***.... with variable speed according engine temperature to switch off and vary fan assisted airflow -- to keep a constant (as possible) engine temperature and to prevent the engine getting too cold. The ducting on that engine was minimal with a couple of guide-vanes -- whereas on the single to 6-cylinder, in-line engines it was varied considerably. What was important, in the multi-cylinder engines, was finding the hottest cylinder and the hottest part of the engine ...

I think in what you are doing -- by finding the hotter places and ducting the air first to those places -- you might be successful in accomplishing a good form of air-cooling --- on the other hand it might be a costly time waster... Sometimes
auto development is that way.

I say that, above, because from experience the optimum directing of air can get baffling (wretched pun!!). You make a new duct with new-baffle plates and the hot spot you had earlier pops up hotter at another place least expected....

Much like a builder here recently -- he blocked up an underground stream and put in a sump pump in his new building´s cellar. A couple of months later he was sued by several house owners when their cellars filled up with water.


I would argue the point about the ducting-baffling causing a seizure during racing -- it should not whilst waiting to go out for a race -- particularly if you have the spark-plug, temperature warning instrument. Sort of takes me back to having Andy´s W/C 250 in that if we had a long assembly wait the water temperature guage would get up to wards 100°c (109°c, higher boiling point because of pressure cap) and I´d shut off for a moment or two. Blipping the throttle aggressively whilst waiting was a bad habit of mine!!

At least Derek, if you make the ducts & baffles removable you can always rip them them off and run naked!!

Have a good Midlands meeting -- regards to anyone who remembers JayBee, and you!!

Cheers!

Hi Trevor - John.
John relax -I sence panic in your writting, no problems its all a learning curve - I did'nt do any of the mods as a result of what you particularly are suggesting, they were already on the bike, some 20+ years ago "so chilli out".

So much infomation, here - Head /Ducts on Fairings /Ducting Transfer Ports /Over Heating /Cool Air/carb setting.

john :- I have been running without lower half fairing see the pictures, but not at Mallory for the first meeting this year as there are improvements that have been gained.

The Fairing:-
specifically the ducting over the head and tubes, - its not shown as it runs, its actually this way for the photo's, the two tubes duct air to the carbs, we tried it many years ago, as others were using them, and found they do work, as we noticed it would maintain the same revs for longer, - without the ducts it would drop off 1500rpm within two or three laps.

Temperatures inside the fairing, we have tried to checked this,!! but its not easy, under way its far lower than when stationary, the fairing inner top duct: possibly the photo is not doing it justice, not quite as complicated as it appears. !

Exhaust front pipe:-
exhaust inperfections, on the front down pipe, - the welding looks poor agreed, but I enjoy doing this, but my welding skills!, its better on the inside, as each joint has been dressed carefully, before the next joint was attached.

over heating
We detected a high temp area behind the down pipe area on the barrel "specifically" the lower fin's behind the exhaust port outlet/duct, temp is very high compared to other areas on the barrel here, we used to suffer a lot of seizures with this, so trying to pay attention to this aspect, I was assuming its to do with distortion,?.

Transfer port windows:-
Trevor don't want to appear thick here,! but I think your refering to the top edge of the port, as it open's and the sides of the port should be square/sharp!, de-burred only.


thanks guys
regards Derek

Thanks Derek!

You´ve made me feel better -- that you´d tried this `baffling stuff´ before, I mean...
Almost said, "Excuse me for breathing...!!"


When Trevor mentioned the Hurricane -- Spitfire incident I really thought I´d given you lousy advice, because the aircraft couldn´t hang about stationery for too long. The oil-cooling efficiency depended on air movement....

The diesel engines I mentioned all had fans à la water-cooling which meant they could be standing still with a Power Take Off loading the engine. I hope I might have cleared up that point with my message above.


Just to bore you a bit more! On our air-cooled, V-8 engine in Canada we had a thermostatically controlled fan which was driven by a fluid coupling, about 8 inches
in diameter, whereby the level of temperature decided the amount of pressuried oil to be pumped to the fluid coupling. The engine never went into production....

All the best!

Cheers!

JayBee for John-Boy.

Thanks John
I like History
Hurrican and spitfires, that must have been the years when engineers became important what a shame this has not progressed today an Engineer is sadly worth a lot less.

regards Derek

Just for Trevor

all the info you have given has in some way found its way onto my bike, but perhaps now with a little more background as to historically plundering away trying different things, untill this year never really new the significance of the transfer ducts so i Hoping the results and improvments gained on the Dyyno with this will result in me joing those racing rather than me plundering at the rear way to far behind to be comfortable for those looking in at me.!

on the Down pipe Trevor Iwas not dissing you comments I understan this if you look carefully, you can see its actually a hydralically formed tube 1-3/4 that has been split front and back very carefully to creat a taper, the bend was too be so there are a few joints.

For all
I know you have registered and following my PHOTOBUCKET, ANYONE IS MORE THAN WELCOME TO LOOK HERE derekbetts,photobuck.co.uk

Trevor what do you think of the photo's George has passed on to me, Ihave promised him all will see i had loaded then to face book but as a result of someone insulting my disability I cancelled my connection Iwas not aware the items Ihad loaded would also automatically do the same, so I need to speak to Edward he Im sure will help me get all these loaded to a disc, we can then pass it to Alan to load them to a proper place on here "for all to see" - some prety amazing shots "dont you think", !

kind regards Derek

I Did offer to help with the photo's but the "call in a mo" is eight hours and counting late...........


Eddie

hi ed

[quote="Edward Pickering"]I Did offer to help with the photo's but the "call in a mo" is eight hours and counting late...........

ok just a busy day, next week even more so have to do every thing this week, I will call you.

can you down load them from my photo bucket, how do I give you access, now that you shown me how to keep it secret, I can not get in myself ?

I will call or see you sunday will bring my lap top.

cheers ed

I was thinking that perhaps there ought to be a special section for photos?

The reason I say this is that recently JohnSBantam put up a pic of a broken gear tooth -- which I saw -- but had no time to comment. Later, when I went back looking for the posting it was nowhere to be found.

There are three possibilities open: "View posts since last visit"... -- not in there... "View Your Posts"... --- not in there because I had not posted my reply ... -- View Unanswered Posts... -- not in there either because obviously someone had answered and it was not me ....

Perhaps I am missing something -- or does it mean that some IMPORTANT subjects could lose the attention they deserve by the way that one went missing for me??!!

Cheers!

JayBee.