I just recently found out about this forum, found many interesting topics here and thought you guys might be interested in what I'm busy with. I got this crazy idea of having the biggest flathead single in our neighborhood a while ago...
I knew 700cc and over has been done, so I set my target at 800cc. A quick calculation showed that it could be reached with measurements of 3.5" bore x 5" stroke.
Suitable 3.5" pistons are available, I used one for Harley Sportster from KB (actually .030" over just to break the 800cc barrier), sleeved the cylinder with a Fordson Dexta sleeve which goes well in the sleeved M20 barrel.
The 5" flywheels were a bit more tricky so I ended up designing them myself and had them machined out of 42CrMo4 stock. The crankshaft is assembled with standard M20 parts.
Another thing I had in mind was to increase the compression to the neighborhood of 9:1 to 10:1, this would necessitate the use of E85 as it sure would not run on pump gas. To achieve this and to improve cooling and durability I designed my own cylinder head as well.
The intake runner is completely redone as there was not enough material in the original casting. I also added a piston cooling jet and use high volume oil pump from ABSAF for to have enough oil for it.
I'm using Gold Star "touring" camshafts for to start with but I guess at least intake side will need more lift and duration.
As you can see this is quite experimental...the engine is not assembled yet and I'm expecting to get the head done in January.
I'd attach some photos here but I don't know how to do it...

email (option): tatu.raatikainen@gmail.com

Hi Tatu. Sounds absolutely fascinating and we really want to see some pictures here. You can email some to me for the time being if you want, and I'll post them up..... Until you master the black art of posting them yourself. Ron

email (option): ronpier@talk21.com

Hi Tatu...A very interesting project...

What is E85?...I'd like to see the head when it's done, and to hear if you manage to successfully run such a high compression ratio..I guess if E85 is the equivalent to methanol you might...

Will there ever be a 1 litre side valve?.. )...Ian

email (option): ian@wright52.plus.com

Ian, E85 is 85% ethanol and 15% gasoline, available in some gas stations here in Finland (and in many other countries). The octane rating is much higher than pump gas and the required richer mixture in conjunction with higher heat of vaporization will help with cooling.
Yes the first thing with that high compression ratio is to kick start the engine...

Hmmm...what do you use for converting inches to mm??? 3.530" x 25.4 = 89.662mm and 5" would be 127mm, this makes 801.9cc.

1 litre is possible...but not with M20 original barrel... ;)

email (option): tatu.raatikainen@gmail.com

And here are some of Tatu's pictures. Ron

email (option): ronpier@talk21.com

Hi Tatu...I do the calculation in mm but got a bit lax with 'rounding up' the decimal places ...
You are quite right regarding the capacity when the calculation is done more accurately...


1mm = 39.37 thou... 3530 divided by 39.37 = 89.66mm..

5000 divided by 39.37 = 127 mm..

radius of bore = 44.83mm

3.142 x 44.83 x 44.83 x 127 = 801.9cc.... Ian

email (option): ian@wright52.plus.com

Thanks Ron for posting the photos and for advise how to post them!

email (option): tatu.raatikainen@gmail.com

You're welcome Tatu. Please keep the pictures and information on this project coming.

Ron

email (option): ronpier@talk21.com

Hi Tatu,

That is really very interesting project.
Lovely work !

Will the piston be sticking over the top of barrel,
Or you are planning to use a tick gasket on the bottom, to take up this space?
(And may need longer tappets also)

The head is interesting-
Did you change the location of the spark plug?
I want to have a nice aluminum head, with a better cooling,
In order to run a 712cc WM20 BSA in a hot country (Israel)
Will you share the head blueprint, or want to manufacture,
If there is a remand here?..

Thanks and good luck!
Noam.

email (option): noam10@gmail.com

E85..(85% ethanol and 15% petrol) Officially classed as a 'corrosive compound' as well as a fuel...

High anti knock characteristics like Methanol allow the use of high compression ratios but it has a lower thermal output than petrol so some of the the gains made from this are lost and fuel consumption is not as good...

I have no first hand knowledge of the practical aspects of using this fuel but there will be corrosion issues for sure, as vehicles built to run on it are specifically designed to accommodate it...

It's not yet widely used in the UK but is available at the pump....

Has anyone here run the stuff?....Ian

email (option): ian@wright52.plus.com

I believe ethanol is the stuff that East European gangs use as a fake alternative to vodka! So as well as being corrosive it will probably make you blind as well!!

A few shots of that and you'd probably sound like you were talking Russian... ...Ian

email (option): ian@wright52.plus.com

I think ethanol is the "good stuff", being pure alcohol as crapped out by friendly yeasts. Methanol is usually the problem with dodgy booze and will cause blindness if you manage not to die. One of the antidotes for methanol poisoning is lots of pure ethanol! Going off topic here, sorry!
Cheers Pete

email (option): petercomley@web.de

I'll remember not to drink any when I get the sprinter running... ...Ian

email (option): ian@wright52.plus.com

Noam, it will be possible to have more of those heads at the same time. However I would like to first try the head for fitment and function, and it is specially made for my application (89,6mm piston with 4mm pop-up) so it may not work on your bike. Of course I can make another version of the drawings to have more "universal" head. Plus, the head is expensive unless a production run of, say 10 pieces, can be made.

The piston pops up 4mm on purpose to improve flow from the combustion chamber to the cylinder. I did not need to use any "stroker plates" to lift the cylinder up as the piston I am using has compression height of 27.5mm only.

Ian, I did ride my M20 on E85 for about 2000km. I used #190 and #200 jets and modified needle on the original carb. It ran and started fine and fuel consumption was, surprise surprise, about the same than with gasoline. I am aware of the E85 characteristics as corrosive agent but that isn't among the biggest difficulties in this project.
And yes it doesn't add power as such but allows for much more compression, I believe 10:1 shouldn't cause problems. The lower thermal output is compensated by using richer mixture. Methanol would be even better but I decided to start with E85 just because of availability. JR dragsters have 500cc flathead singles running on methanol with compression ratio of about 15:1, they produce approx. 50hp and rev as high as 8000-9000 rpm.

email (option): tatu.raatikainen@gmail.com

Are the JR engines using fuel injection or pressurised induction?...

If not I'd like to know more about how they maintain the gas flow with such high compression ratios....Ian

email (option): ian@wright52.plus.com

I admire anyone wishing to explore the boundaries of our WD machinery.........interesting stuff...

But for me, call me an old stick in the mud, but I prefer to keep 'em as they were with perhaps just the slightest tweak to improve on that classic "performance".....

It's a good topic tho, and nice to know what CAN be achieved with our old iron.....

I can see that...My interest though has always been the mechanical side of things and what can be done with it...

Believe it or not I like to keep my WD bike looking, at least, reasonably 'standard' and to that end none of the changes I have made are visually obvious...and I am rebuilding the original engine as a completely standard unit to go with the bike when it is eventually sold...

So nothing is irreversible...

The WD bike is a separate interest to my other bikes though...none of which are standard at all...

Whilst building a 'catalogue' bike can be rewarding, after so many I found the process too restrictive in that it didn't let me express my creative and engineering skills sufficiently..

Nothing unusual really, the motorcycle world contains every possible permutation on 'how to do it'...and long may it be so...Ian

email (option): ian@wright52.plus.com

Likewise Ian , i find it more interesting having a bike not fitting the norm ,but its great that we are not all alike , makes it so much more fun i reckon .
I have built one bike to as near standard spec as i could , it was number 11 off the BSA B33 production line , approx 1947 i think ? (long time ago ) ,anyway i thought that one deserved being somewhere near correct ,never done another , i just find special builds far more interesting .

Like to see the results of this, but its over 60 years too late! The British army could have used them as mobile grenades!

Thanks Tatu.

Maybe making more heads later, can be cheaper,
As it can be made of a good quality casting (Sand casting?)
Made as a copy of the original,
Which would only need some finishing.

This one can even be made with a smaller combustion chamber,
So can be used as-is, or with a ticker head gasket, if a lower
Compression-ratio is needed, or machine some material, instead.

It is always easier to take some material out, than put in..

I asked regarding the position of the sparkplug, as in the M20
it is located directly over the inlet valve, but I saw modifications
Made to the head, to position the Sparkplug in other places,
and also some modification to change the gas flow..
I remember that Ian W. has done some good research..

Anyway, hare are some examples for alternations.
Some are from the internet, and some, (I think) made by forum contributors.
I hope that "Photobucket" would not cut the photos too much,
so the details can be seen.
Cheers!
Noam.


Not M20:

email (option): noam10@gmail.com

One interesting thing about modified sidevalve heads is the varying amounts of 'squish' and the varying shape of the squish area...

This probably comes from the two schools of thought regarding tuning work on SV motors...

One favours gas flow over compression ratio...The other compression ratio over gas flow...

I'm a believer in the highest possible gas flow as there seems little point in a high compression ratio if the cylinder is poorly filled and there isn't much to compress...

The 'calculated' compression ratio assumes a 100% full cylinder...In practice this is never achieved, but it seems logical to me to go for the highest percentage possible...(I'm assuming naturally aspirated engines here)...

'Breathing' or 'Compression' heads tend to be quite differently shaped around the squish area, the area around and over the valve and in the roof of the combustion chamber....

As is often the case it's a matter of which 'experts' you choose to believe when planning the initial engine modifications.... Ian

email (option): ian@wright52.plus.com

Here's my head and cylinder, now running in. The spillway in the cylinder takes off at the top edge of the lapped valve seat and ends just above the top piston ring. Pop-up is .186". The head shown has had the ceramic insulation removed and some gentle relief of the leading edge of the squish plate. CR is 7:1.

I can offer 2 inch Manley intake valves with springs, keepers and collets like the one shown if anyone is interested. Also an ex valve, 2mm oversize to salvage burned seats, in current alloy steel.

These valves are US-made custom items of NASCAR spec. Springs are from Iskendarian, intended for XK Jaguar. Price will depend on the number of orders. If anyone is interested I will work up a price for the complete set.

Jeff Bandola

email (option): jjbandoo@aol.com

Hi Jeff...I'll take two pairs of valves as mentioned in my last e mail..Plus 3 sets of the associated hardware..collets, springs etc...Ian

email (option): ian@wright52.plus.com

How's the big SV going?

I guess the real experts at tuning SV's are Hardly-Ablesons, there is some fascinating work they did, trying to keep SV's competitive.

RE Air-flow Vs CR
One major problem with SV's - i do tend to agree with your gas-flow over CR, idea.

One thought - look at a good digital, programmable ignition system - I gained +20% torque and ~10 bhp on my racing mini engined Berkeley, with a decent ignition system.
Basically BMC A series engines are breathing limited (like a SV), but with some work you can get the CR up to around 13-14:1.
The high CR can be used to 'fill in' the low rpm torque curve, enabling you to concentrate on high rpm gas flow. As you say, filling at high rpm is imperfect in these engines.

On std unleaded petrol (never bothered with avgas, etc), with time on a dyno and a programmable ignition, its surprising what power can be released.
(currently working on a B50 MX ignition system, with EXCELLENT results)

I've long thought that internal combustion engine development peaked during WW2 - the only progress since has been in ignition and fuelling electronics.

email (option): GINANTONIK@TISCALI.CO.UK

all this talk of making the m20 engine bigger wouldn't it be easier to put a modern 500cc engine ie Japanese it simpler and cheaper

email (option): roger.beck@node6.com

It would Roger....In fact I could just go out and buy any Japanese sports bike from 250 upwards...

But that would cancel out the whole point of playing with an old machine just for the fun of it, the interest and the challenge....

Nobody said it had to be logical.. ...Ian

email (option): ian@wright52.plus.com

Aloha,

Finland, you say. Does that mean that I will get to see this at Norrtälje in June?

...eh, perhaps I should explain to all non-nordic forum visitors that Norrtälje is the place for the largest Cumstom Bike-show in nothern Europe, just outside of Stockholm. This was for instance where Stellen Egeland premiered his Hulster 8-valve if anyone is familiar with that one (if not, it's worth a google).
And although the show is in Sweden later years the finnish builders has outshined most of the things built by the Swedes. Some wonderful creations over the years using old material to build new things (forget billet chrome and so on).

One thing I really like about the M20/21 is that there are so many of them that you needn't feel any guilt if you don't go original. And also I think it's great that there are people who do put so much effort into making their bike exactly the way they where, down to every nut.
There's room for everyone when it comes to these bikes. I think!

dear monster, these flywheels are one amazing work of art (said by someone who works in metalworking)
best of luck - and please- after its done take a short video and upload to you tube,
just have to hear this one running....
ori

M20s go much faster if a) you lose a couple of stone and b) when going long distances you go with your mate who has a Ural combination to carry a stone of tools and camping gear

email (option): sacombsashtrees@hotmail.com

.....once the were considered as one of the most reliable bikes.......
but I can understand what you say.....

they..... not the....

Hi Ori...They still are one of the most reliable bikes....Ian

email (option): ian@wright52.plus.com

In 8 years of riding the WM20, between 14 and 200Km for a ride,
Mostly in hot weather, but also in rain and even through a river one time..
I never got stuck with it..

The only problems I had from time to time was with the magneto,
After long trips in hot weather, but the poor mag is 70 years old,
With the original capacitor.

I got a fully reconditioned one now
(Wounded, re magnetized, new cap, new sprocket, clutch and points)
Which I'm about to install, so that would also be fixed, hopefully..

Noam.

email (option): noam10@gmail.com

There is some progress with it, I assembled the bottom end and received the new head. The cylinder is at a machine shop still for the valve job. Maybe one day they get it done.

The bike should be running in about a months time, sure will post a video of the initial start up.

Simon, maybe not in Norrtälje but somewhere else in Sweden for sure IF the engine is still running...

email (option): tatu.raatikainen@gmail.com

Hi Tatu...I see you have two inlet tappet heads fitted..

If my 720 is anything to go by you are going to need the valve lifter...

How do your new flywheels compare in weight to a standard M20/21 set?...Ian

email (option): ian@wright52.plus.com

Ian, I'm not going to use the valve lifter. That's why two intake tappet heads. I'm using a decompression valve for starting and weak enough idle to kill the engine. If the throttle gets stuck...I guess I'm screwed :D

The 5" flywheels are slightly heavier than the original ones That is to be on the safe side with increased displacement and compression ratio. We did weigh them but I don't remember the figures...could have been around 5300 grams each??? I believe I can check the design weight from the model if necessary.

email (option): tatu.raatikainen@gmail.com

What's the plan with those oil lines?
Also I see that you have what appears to be a "homemade" aluminum cover for the oil pump?

Beautiful work all of it I must say, that crank look really great! Can't wait for the youtube videos of this one running (on the dyno )

Keep up the good work!

Hi Simon,

That oil pump cover is not home made..
It comes with the set of the high volume oil pump from ABSAF.
It is deeper, in order to contain the oil pump,
Which is about 30% longer the original BSA.

The internal design of the pump is different,
It had only 8 teeth per sprocket, instead of 12 (13 for goldstar) but wider.

Noam.

email (option): noam10@gmail.com

Simon, the short oil line is for the pressure gauge and the long one for piston cooling jet (which might work or not). The oil pump cover belongs to the ABSAF high volume pump (Gold Star goodies) which is about 10mm taller than the original pump.

email (option): tatu.raatikainen@gmail.com

On the left, a normal M20 oilpump, newly CNC machined, on the right-
ABSAF high volume pump (30% more output reported) and oil pump cover

email (option): noam10@gmail.com

Hi Noam..Where did the CNC M20 pump come from?...Did you just buy the body or the gears as well?...Ian

email (option): ian@wright52.plus.com

Hi Ian,

Some guy used to sell these on eBay, some 6-7 years ago.
He sold the body, and you had to complete it with the gears and plate
From the old pump, and the ring around the actuator drive.
He just stopped selling them one day.
I do not remember who he was, and I do not think eBay or PayPal keeps
Records for that long. If they are, I will be happy to check who it was.

I bought 2 off him, one is still working on one MW20, and I got this one
out od the other, cause I had some oil circulation issues, after first
Start up of the motor after rebuilt,
But it turned out not the pump's fault... I need to put it back in.

Cheers,
Noam.

email (option): noam10@gmail.com

You may be able to find the seller by checking the feedback left for you, or that you left for him. Might be a long job, depending how much stuff you've bought.

email (option): horror@blueyonder.co.uk

Hi Horror,

GOOD THINKING !

I will try to do that, though I do not know if he would still make them.
It was so long ago.

"Draganfly" sells something very similar,
But they ask for your oil pup in advance as exchange,
And move your old gears and bottom plate into it.

Noam.

email (option): noam10@gmail.com

Thanx for info!

Now I am of course curious about the piston cooling jet...

OK,
So I'v tried to find the oil pump seller from years ago by feedback but I got:

"Detailed item information is not available for the following items because the Feedback is over 90 days old."

I will try looking at Paypal history.

Noam.

email (option): noam10@gmail.com

Hi, I´m new to this forum.
I´ve got a -43 M20.
Very interesting engine, I really like it.
And the video of the test ride made me really happy

email (option): anders.lundkvist@swipnet.se