Water cooling know-how

Hello all,

I am just about to make a big change to my Bantam engine and convert it to water cooling. I have experience on cooling systems for bikes but not a air-water cooling conversion. I've been sent quite alot of information of a friend to help me with this. My dad has alot of know-how on this subject i.e. plumbing which practically follows the same principle.

I will probably go for the bog standard option i.e. second-hand radiators etc etc. Are there any tips/guidelines/ materials I should know about before doing this.?

Cheers,

Tim

*Note* I have just been offered a complete Bantam water-cooled barrel, head etc. The bore is 52.75mm accordingly.*

Tim! ...make sure the `cooled´ water goes to the hotest places first and ensure it does circulate properly. Over-cooling can be as bad as undercooling and bad circulation can cause distortion resulting in seizure, detonataion and other nasties...
I´m sure there´s a lot of good hints out there Tim -- maybe this will get them started.
A pressurized rad cap helps because it enables the boiling point temperature to be increased and that improves cooling efficiency -- or in other words enables the use of a smaller radiator for the same cooling effect.
Why don´t you keep things simple to start with and get an air-cooled Bantam to work properly first...?
Cheers and good luck!
Isa hassbinn.
JayBee.

Hi John,

Cheers for the info! I've managed to ground-run my engine on a test bed.....the garage floor

Terry has given me the design for his barrel and head which he just needs to finish:



He said he was unsure about the rules if you still have to keep the bottom and top fin on? But I'll check that out...

Cheers,

Tim

No one bit Tim! I had expected lots of retorts....

My statement should have read, "... that the cooled water be directed to the hottest part of the cylinder first...".
In the air-cooled engine the fins are smaller at the bottom than the top for that reason: during full-power time the barrel is wider at the top than the bottom because of that temperature difference and a well developed cooling system reduces that difference to a minimum. You´ll often see DIY, two-stroke engines with water-cooled barrel and air-cooled head. This set-up works very well because the head temperature should be kept high for good combustion and it makes it much easier to get at the piston during race meetings...
The spark plug should never be too hot nor too cold. There is a means of knowing this by the copper washer (under the spark-plug) and I thought someone would have mentioned that by now....
I am far from being an expert on Engine Cooling but I have seen the results of badly made systems (in 4stroke diesels ) where localised boiling has taken place and the cool water gets channelled away from that hot area -- because the pocket of superheated steam acts as a blockage ... with the obvious disastrous results....
Cheers!
JayBee.

John were you refering to the pear shape D1 barrell 48-53? being able not to distort because of fin size(shape)? Before they went to 55mm wide stud cylinders - not pear shape.
Ref big diesels- I worked for Kassbohrer Setra Gmbh in the UK for a number of years and they had trouble with Mercedes Benz V8/V10's ref localised boiling and cavatation of the wet liners. There 'German' answer was 'This is not a problem, just change all the wet liners!!'

Cheers Mike and John for the info. I've managed to buy an original water-cooled manual (off Ebay!) for £3.99. 4 double-sided pages with alot of technical info.

This is the other drawing Terry just emailed me:



Just to check whether this is race-able due to rules. Mike I think you have an email or a PM from me. Don't know which one I clicked!

Cheers again,

Tim

Hi

This barrel was built a long time ago, while I was still at school, early 70's, it was never used to race. The porting was taken off the blue brint from George todd, modest with two std transfers, Dad made it and used it for experimenting, but once he found the distortion, we decided to stick with an air cooled iron barrel to start my racing career with, never thought it would turn up on here, it was such a simple idea though, fab.

Derek.

What type of distortion was there Derek?

Hi Tim
Just a few words of wisdom.
walk before you run When starting Bantam racing keep things simple I would recommend
to stay air cooled till you have more knowledge.
To Win you have to first finish.
I was told along time ago The race starts at the front door
You first got to get to the meeting is all your kit ready will your transport get you there ask tony davies about that one
Dont fix it if it's not broke many be I should take note of that one why redesign the wheel may be that one too
Good luck with the bike
many see you at some meetings this year with or with out a bike
Robbie

Hi Robbie,

Thanks for the words of wisdom. I probably will go air cooled for some and water cooled for others. I am coming to Mallory on the 5th April but not March since of school. I will try to come to most meetings of the year. Bike will probably be finished early April/May but will take ages to get license sorted though. Probably be competitive by end of season i.e. late August/September.

Have a good day,

Tim

Carrying on from Mike -- how even an American Diesel engine manufacturer can make disastrous design mistakes.
...
This interesting diesel cooling problem occurred in South America. Its solution was not bothered with for a very long time. The palliative was the way you said, Mike, just change the liner. The problem showed itself by having water get into the cylinder and in each case no hole, as the cause, could be found. ..
It had happened several times and when the foreman told me about it he showed several lines that he had kept... Porous liners he told me and the engine manufacturers have changed the supplier.
Part way along the liner, where the water came in at it, were tiny marks of cavitation-erosion which had been ignored as `always happening´...
These places were as if sand-blasting had ripped out a few bits of metal -- not really much at all -- about the size of an old fashioned farthing...
The water came in towards the liner through a small hole (at each cylinder location) and the foreman would not believe that this was the cause of the problem. The holes were too small and the velocity of the water in conjuctiion with the heat was sufficient to cause the erosion.
We plugged both ends of one of these `porous´ liners which had been filled with water and whilst cool nothing leaked out . When the whole contraption was heated to about 150°F (74°c) a constant drip became apparent.
What happened when the truck was left overnight was that a quantity of water would seep in -- frequently insufficient to cause `Hydraulic Lock´-- and the diesel would then start up on (say five cylinders) and misfire for a while until the water was gone.
...
I never heard of this happeing with petrol engines and I guess as far as Bantams go this info is of not much use -- but I enjoyed the telling and if a Major OEM engine manufacturer can make a silly mistake so can some Bantam builders.
...
Go well and stay well,
JayBee -- for John-Boy!

Seems quite a story you have there John! I think it would apply for the same principle to petrol engines but I am not sure!

Just a quick note, I was searching round the net and I found this quite remarkable picture:





It was at a rally of some sought at the Sammy Miller Motorcycle Museum not that far away from me. A V-twin BSA Bantam...

Quote: Without doubt, the most bizarre bike of the day, and one which I would have given anything to have a blast on, was a V-twin Bantam! The bike has been around for a while and was built as a sprinter by using two Bantam motors welded together in tandem, driving via the rear engine's original gearbox. There were plenty of people scratching their heads and asking 'how?' -- but the big question is 'why?' I never did find out the answer but I'm so glad there are still engineers around who are eccentric enough to embark on projects like this. The bike was fired up and Sammy took no time at all to grab the chance of a quick blast around the car park.

I didn't take the picture but can anyone identify who made this marvellous bike? Looks to be quite complicated.

Tim[i]

My last salaried postion was with KHD Canada Inc... where we tried for the US HUMMVEE-HUMMER military contract which, of course, GM got with the HUMMER. That´s the Jeep-replacement vehicle -- you see on Telly running around Iraq and Afghanistan thees days...
...
KHD Cologne had a great history of air-cooled diesel engine development with modular*** design and one thing of interest, in production, about that was overcoming distortion by head-tightening-to-barrel distortion and thermal shaping effects... The final honing of each cylinder barrel was with a collar clamping the barrel with the force equal to that of cylinder head tightening torque. The bore was tapered with the bottom dia made larger at the bottom. The pistons were tapered (crown to below ring gaps), barrelled (over the main body of the piston ) and had double ovality from crown to skirt. We are talking of microns here, with dimensions arrived at over many months of dyno testing to establish the optiimum oil-consumption coupled with best all-round performance -- quite different from the racing scene needs yet somewhat similar to how pistons are finished these days.
...
***each finned cylinder-&-head was seperate for ranges of engine families, from one to 14 cylinders per engine.
...
I guess my old practice days at Brands did much the same: half an hour of `running in´ at gentle speeds and revs followed by stone-honing the high spots until -- at the end of the day -- the motor could be thrashed mercillessly for half an hour.
What patience that required -- poodling around, wanting to have a real go for maybe three sessions with the hand-honing of the piston high spots in between....
...
But those were the days. No licence needed and 10 Bob a practice session...
Ahhhh!
Byee!

Seems to be good. I know the old HUMVEES had problems with the cooling etc when they went through dusty terrain etc. The old Chieftain tanks had about the same problem. Most problems included, cylinder liner failure, fan drive problems and perpetual leaks due to vibration and badly routed pipework.

However, as the engine power improved the tank itself became heavier. The tank was steered by conventional tillers hydraulically actuating onto external brake discs. The discs worked via the epicyclic gearbox providing "regenerative" steering. In reality the discs and pads became soaked in oil and diesel and the steering became difficult.

Did that happen as well upon the engines you were working on John? I've seen it happen before in my Dad's VW Touran but mostly it is easily sorted. Not like that of a tank!

Have a good evening,

Tim

Hi Tim!
Only the HMMVEE, never tanks -- although I watched them perform and drank a few gins with some REME officers one time... I was mainly a specialist on engine and diesel fuel injectiion systems witha bit of HGV Fleet Transport consultancy thrown in...
Cheers!
JayBee!

All interesting stuff!! Hope you get this water cooled engine up and running it would be good to had some more 'boilers' out there...

Hi Mike,

I'll try to get it running as soon as possible. I'm going for the 50X56 option which is alot easier for me. Since I cannot go for the 54X54 option, I am going to have to use Alpha rods etc Omega pistons like they used to in the 60's etc. I'm still going to use the RD250 flywheels just skimmed round the sides for a good fit.

BTW-what radiator do you use? I've seen that the DT125 radiator is small and reliable and will fit good upon the Bantam frame.

Cheers,

Tim

Omega and Alpha better off using a packet of crisps and half a dozen eggs. Best advice is to go air cooled (btw) don't think anyone's built a successful W/C (a lot of work) in the 30 yrs, most the ones running now were built in the 70s though I could be wrong as I wasn't around in the late 80/90s. I tried building one with very little knowledge and suffered leaks and distortion though it still runs to this day.

Big question Tim your 12/13 yrs old 6 and a half foot why bantams?family history with bantams?

we did it back then because it was cheap entry level racing, once you've done it your hook for life though

If you are serious about racing a bantam you will need a reliable bike, there's nothing more heartbreaking than spending loads on entries, travel, bike prep, riding gear etc just to sit there watching from the side of the track after just one lap, been there like others on here many times before

Good luck


Tony

Tim i think you are confused? 1 Ref bore and stroke - you can't go 50mm stroke 56mm bore on a D1 barrel (52stud pear shape will break through cylinder wall. 55stud round-ish cylinder v.thin may break through!)
2 Ref RD250 crank will give you 54mm stroke, the stroke is determined by distance from centre of crank to position of centre of crank pin (x2). The crank determines stroke not conrod length.( N.B.Rod lengths std bantam(also alpha) 125mm Yam RD400 115mm Yam RD/TZ 250 110mm Suki RM125 100 and 105mm). 3 Ref BTW is the man for ally air cooled engines!?
And Tony just to let you know both Ian and I will be on 'new water cooled' engines this year. Ian had some win's on his engine last year during test and development sessions using my 003 bike for running gear!!

mjpowell wrote:

Tim i think you are confused? 1 Ref bore and stroke - you can't go 50mm stroke 56mm bore on a D1 barrel (52stud pear shape will break through cylinder wall. 55stud round-ish cylinder v.thin may break through!)
2 Ref RD250 crank will give you 54mm stroke, the stroke is determined by distance from centre of crank to position of centre of crank pin (x2). The crank determines stroke not conrod length.( N.B.Rod lengths std bantam(also alpha) 125mm Yam RD400 115mm Yam RD/TZ 250 110mm Suki RM125 100 and 105mm). 3 Ref BTW is the man for ally air cooled engines!?
And Tony just to let you know both Ian and I will be on 'new water cooled' engines this year. Ian had some win's on his engine last year during test and development sessions using my 003 bike for running gear!!

Mike thanks for putting me right on that, knew of one in testing a couple of years ago but had leaks and was scrapped or was it?

Tony

Weather last year they were all watercooled Bantams

Heres to a sunny season

James

Tony , Ian had an unsuccessful water cooled motor about 4 years ago and yes generally all w/c motors are ancient my 001 cylinder and 002-Chris Bennion (ex001 6transfer!!) are circa mid seventies 004-Phil Betty(ex002 Tom's first reed valve) 1983, but Nick Bramleys w/c is a new(08?) copy of the Colin Hall championship winning motor of 1989.
Easy option - Air-cooled BTW.
Interesting option - water-cooled - only for the brave, fool-hardy daft!!
Mike

Tony, to answer your first question, in my view, Omega and Alpha, Arrow etc all that lot are OK to use! Most people they would be utter useless but to me, they're as good as Japanese internals (maybe even better in some cases).

Yes, to answer your big question, I am 6' 3" (parents are tall) but the thing why I chose the Bantam was the appeal of having a descent, classic racing motorcycle that most people, riders or not, would enjoy to see and ride. (Anyone agree with me?)

As with the family history, my grandfather's first bike was a Bantam(?) plus he owned alot of old Vincent's, BSA's, MAtchless's etc plus I think some Roll's, and a 1930's Lagonda Coupe. He had a workshop with possibly the most amount of tools my father has seen. Myford Super 7 lathe, MIG welder etc list goes on. Unfortunately he died in 1993 and my grandmother scrapped the lathes, milling machines, welders, practically everything related to engines. Plus the bikes and cars he had collected. Total waste. At the time my Dad didn't have the idea of inheriting his father's tools, cars and bikes and most were sold for nothing. But until now, we both have realised how much we need those utilities and it would've helped me alot. My grand-father would've been extremely interested in your Bantam's and probably wouldn't leave the track! Is a shame.

Plus since Dad saw this website, he is also hooked on racing Bantams...

Also it's simplicity is that what caught me as well. before I had the idea of going classic etc I had ideas of riding in the Aprilia Superteens but since most of that is extremely expensive i.e. £2500+ each season excluding bike, transport, kit etc!?

Just to add, the porting outline for the W/C barrel was taken off one of George Todd's blue-printed, winning engines.

Mike, in order for me to use Japanese internals is that I have to take 13mm off the crankcases which, I do not have the facilities for.

*NOTE* I will not be rushing this. I am taking my time as slowly as possible as to get the benefit out of using the information, materials etc I have for my learning and expertise.

Since I have limited money, plus nearly at the end of my tether with it, I won't be finished for a very long time.....

Think I've answered everyone's questions??

Cheers,

Tim :/

Final word Tim!
Your enthusiasm shows and it´d be a pity to bash it on the nut by finding out that at your height -- and weight, no doubt -- render any effort by yourself and machine as uncompetitive -- before you even get a leg over the saddle. In other words it wouldn´t matter if you were on a super-duper, W/C and the hottest Bantam racer in the world -- those two might factors have you "riding" at the back of the field -- killing off your enthusiasm for racing...
...
Have you ever practiced? Maybe better if you could borrow a Bantam -- or other 125 Bike -- and do a few practice laps, on a practice day -- before you invest too much in the highly specialised machine ...
...
I´d appreciate a remark from Mick Jones on this weight-height factor relative Bantam racing -- I know, Mick, that you went from Bantam to racing 250 with considerable success in the latter.
The picture, I have by my desk, has Mick Jones a head taller than Mick Scutt so I guess you were over 6ft Mick? and what was your racing weight?
Other than than that Tim, I wish you all the success in your endeavours...
Go well and keep well,
JayBee -- for John-Boy.

Hi John,

I have ridden a road legal bantam but never ridden a race one. I have also ridden small pocket bikes and an odd Aprilia race bike for one time and that's about all. I'm a pretty competitive rider but never get the chance to shine on a bike.

As you said about borrowing bikes, I've seen in the CRMC and a bit in the BHR that someone suggested there should be like a 'buddy system'. This is for new riders and helps them through their first (well...not more than that!) season i.e. helping get bike ready, simple pre-checks etc etc. Does anyone else think this is a good idea?

Tim