Hello all
I am finally looking at getting my Wm20 engine rebuilt.
I have a NOS conrod, inlet valve and guide, new springs and valve collars, new cam followers, new cam shafts, new bearings, shims and bearing clips and Heplex pistons minus rings. I will see if the big end bearing is still good.(can you re machine the big end bearing and use oversize rollers)?

Still looking for rings and a NOS exhaust valve.
Would anyone suggest someone in Melbourne Australia where to get it reassembled , get it bored, balance the flywheels. Etc.
What should it cost to get it done and am I forgetting anything.

What is the best procedure in getting it right??

Cheers Darren

email (option): Darrenacartwright@yahoo.com.au

Hi Darren,
Talk to Basil at Headworks in Murrumbeena.
95685226

email (option): spacemonkeym@gmail.com

Matty
I have already called him today before your reply,
Even with my supplying all the parts he wanted $1000 to assemble it and hone the cylinder .
Seems pricey to me, as I can get the cylinder honed for $70 at Dandy rebores. Flywheels balanced for $75.

Any other suggestions

Cheers Darren

email (option): Darrenacartwright@yahoo.com.au

$1000!? Whoa.

email (option): spacemonkeym@gmail.com

The only really hard job is presing up & truing the crank.
after that it is a "kitchen table rebuild ".
They really are simple bikes.
Mechanics down here charge $ 50 to $ 100 / hour ( so they can pay the unelievably greedy land lords ).
If one was to do an exclusive rebuild there would not be much change from 10 hours so the labour charge is not that unreasonable.
Remember that the mechanic might do one or two M 20's in a year so it s not like rebuilding a local V8 which they could do with their eyes closed.
Once upon a time I would not leave a barrel with any one who did not recognize it when I pulled it out of the box. Now days I feel blessed if they can work out that it is from an air cooled motorcycle.

You could try ;-
Ace Classics
Euro tune
Union Jack
Central Motorcycles

email (option): wariron@tpg.com.au

I don't know if you have everything totally prepared (apart from the crank and honing) but it doesn't seem like crazy money to me..If the crank tapers are worn at all you can soon use quite a few hours messing about to get it to run true...And don't forget that price isn't his wages..he has to rent his shop, insure it, run the machines and lighting, cover the various consumable items, factor in something for wear and tear on his tooling (which will have to be replaced sometime) and then take time to assemble the engine carefully. So as well as paying for his expertise you are also hiring a fully equipped workshop. They rarely fit together neatly at the first attempt either in my experience unless everything has been extemely carefully prepared..ie deburred, threads tapped out, oil pump prepared correctly, tolerances checked etc. etc.....Ian

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

$1000AU equates to about £654. Professional engineer shops here in UK will be charging about £40 per hour, and then probably + VAT at 20%. So that would be the equivalent of 2 X 8 hour days...... Of course there are always cheaper options. Ron

email (option): ronpier@talk21.com

Gents
Thank for your thoughts, I too are a tradesman and have invested
hundreds of thousands in tooling and machinery, and understand the on costs.
Beening a Joiner I am not aware of the time and procedures need in a rebuild.
To me they look like a glorified Victa lawn mower, and quite easy to re assemble.

Trevor yes I have had my V8 rebuilt for less, how did you guess that's what I have.

So would I be best just to get the bottom end rebuilt?
Then tackle the top end myself , as I am still looking for parts anyway.

Any further suggestions and advice are welcome as I not aware of the processes involved, being a dumb Chippy.

I still need the magdyno rebuilt and was going to us Gale at Blue Spark (about a $1000)
Gearbox i want to rebuild as I have new bearings and bushes for it.
Rims are a little pitted on the inside is that ok or in need of a rebuild.
Carby will need a rebuild but I believe John Parker has the parts.

If anyone has any suggestion or advice please let me know

Thanks Darren

email (option): Darrenacartwright@yahoo.com.au

They are a simple engine but with seventy years of wear and abuse, anything could've happened. They do need more skill than simply bolting parts together. If you have no experience and want a good chance of a reliable engine that won't need doing again then professional help is probably a good idea. The trouble is he's likely to find additional things like mag platform and oil seal, etc.

Reassembling the top end is not difficult but also not a large part of the bill and you'll have to make sure that the rebore is done correctly and the rings are properly gapped etc.

If the rims are only pitted and not on the point of the nipples pulling through then a wire brush, rust kill and a coat of paint should be fine.

Hi Darren, My advice would be to get the jobs done that you KNOW you can't tackle and then have a go at what's left....These aren't really difficult engines to reassemble and there are plenty of people here who are happy to give advice...
The other way to look at it is how you can best spend your time...It might be the case that if you do a couple of paying joinery jobs in the time you would have spent working on your engine you will generate the cash, by means you are familiar with, to pay someone else to do it...
The good thing about doing it yourself though, even if it is hard work first time, is that you'll never have to pay someone else in the future...Ian

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

My intention was originally to do it myself so that I could in future be able to do it myself, as I cannot take it down to the local bike shop. I would love to be able to rebuild the engine myself, but I am unsure where to start as such. These skills are being lost and I would love to learn them for myself.
So I take it that it is not a matter of getting the flywheel balanced, installing the bearings etc and bolting the bottom end together, as I said I have a new conrod, shims bearing clips and bearings. What information am I missing?

email (option): Darrenacartwright@yahoo.com.au

Gday Darren, any mechanic should be able to work out how the engines goes together. If you show them the manual and give them all specifications they should be able to assemble it without to much trouble. Is there someone you know that could help you put it together. That way you can learn for yourself.

I learnt as a teenager from an old speedway racer how to built english bike engines and motorcycles in general. Unless I learnt from him I dont think I would have continued my interests in old motorbikes because before his help I knew very little.
It does get expensive when you have to pay somebody else to work on them. Over the years I always like to do everything myself including truing flywheels which I learnt from the same old fella 35 years ago.
The only thing I dont do is magnetos and generators I can pull them apart and put them back together with new parts but there is more to it than that. They need rewinding etc and re magnetizing for magnetos so you have to pay someone sometimes. I also pay someone to cut valves and seats and rebore these days. Even though I know how to do it and have done these jobs in a engine reconditioning place I dont have the necessary equipement in my home workshop.
Darren if you dont have any mechanical experience at all I would suggest that you not do it yourself without help. Is there a motorcycle restorers club of some sort near you? There may be some old retired fellas there that would be willing to help you. That way you could pay them as you learn.
Another idea is to get a few old engines and pull them apart and put them back together for practice. You might break some things but I must admit I broke lots of things trying to learn how it works.
I am willing via email and phone calls to give advice and step by step info if you need help. I'm only 2000 KM north if you wanna bring it over instead.
cheers Terry

You could also try joining the BSAOA Vic .
They are a very active club and there are always members who are willing to give a genuine novice a big hand with the trickier bits and lend tools where needed or even do some machining ( we all like to show off to a newbie )
Clubbies are always happy to find a new rider but are a bit wary of shysters looking to turn a junk pile into a few quick bucks.
When dealing with the specialists, be patient most of them will give you reasonable value unless you start to hassel them when it becomes a case of "the more you pay the faster I work" and if they suggest a modification, do it .
None of them are looking for more work to do.

The War Office could have ordered much better bikes than the WM20 but they new what sort of conditions they would be ridden in and the types of places where they would have to be repaired.

A digital camers will become your new "second best friend".
Take your time , photograph every thing before you pull them apart, & during the dissasembly .
If you can read a micrometer & vernier then you have 90% of the skills that you will need.
Before you start decide exactly what you want to do with the bike once finished this will make a difference to how you go about the restoration.
A "rally bike" will happily use a monoblock or even concentric carb ( like mine ) wich are cheaper & easier than the original 276.
The biggest time eater is stripping & cleaning and no tradesman want to wast time cleaning crud off so that they can make accurate measurements.
Anzac weekend will have us all at the All British Rally Newstead come along for a meet & greet.
Bike Beesa
Trevor

email (option): wariron@tpg.com.au

Terry
Thank you for the advice and offer, I will keep it mind. The distance is an issue unfortunately.
I do have some mechanical knowledge, I have re built many a hz model Holden and even a Torry. But no engines.
I would love to gain the skills to work on the WM20 and the W34-7
Thanks again

email (option): Darrenacartwright@yahoo.com.au

Darren,
I was also very nervous originally about touching my M20 restoration, but was pleasantly surprised once I stripped the bike apart just how straight forward the mechanics are, I'm very fortunate working in a machine shop that has paid dividends in allowing me to machine, rebore and polish all parts, but I'm sure you will gain a great deal more satisfaction out of the project by having a go, really is a great bike to work on and this website is the best place you could go to for advice and support.
Julian

email (option): 79Aust@sky.com

Trevor
Not trying to sound rude and sorry if it sounds that way, if so I apologise.
I tried to join the club twice, sent in the form and a money order for the dues twice and never heard back.
I have been to four meetings and didn't get a particularly warm welcome, when they found out I was tring to restore a Wm20. Maybe the plied arms tattoo on my arm put them off. Ha ha.
I understand there are people joining the club to get access to cheap parts, but that not me.

The reason I picked a wm20 was to honour my grandfather who rode them in North Africa with the 2/9th during the war.
Then nearly died on one after the war.

I have rebuilt a few of my Jap bikes over 20 years but no internals.

I would dearly love to be able to get the assistance of someone, to help me with the engine. I would love to learn rather just handing it over to a mechanic.

All my parts are clean, the bikes are in the house. Unfortunately it is impossible to take measurement photos etc ,as I have built what I have from individual parts ( about 90% complete). I started with a gearbox shell. Yes as friend of mine puts it I like to make tyres from scratch.

Thanks all and cheers
Darren

email (option): Darrenacartwright@yahoo.com.au

Hi Darren, it's Nick the young bloke from Mordialloc way, we spoke on the phone some months ago.

Here's my M20/M21 bitsa up on the bench slowly going together



Basil recently rebuilt a friends old three-fifty Honda twin motor and i can wholeheartedly say it is better than new. Basil has been in the game many years and is well respected amongst all manner of MC enthusiasts for good reason, however I don't believe he is any rush to take on new work given his current state of health.

I've obviously not progressed as far as you have with my build but have a similar mission statement of doing as much as possible myself. Perhaps Ian is right, tackle what you feel confident with and outsource the rest, it might even pay to try and find a reputable classic motorcycle mechanic or restorer who will take the time to allow your to look over their shoulder as they do the valve seats, rebore and crank assembly so that come time for renewal you might be more willing and prepared to tackle it yourself. Money is tight for me and the M21 and my B33 are the last on the food chain so come time for me to do the motors I will be giving it a go on my own armed with the manuals, parts books, and all the other relevant literature i've amassed over the last few years (which you are most welcome to borrow if you wish), i'm no mechanic, just a librarian but many an M20 owner back in the day would have tackled such jobs themselves so I may as well try.

good luck mate,
Nick

Firstly I have been riding BSA's for over 40 years so my hide is that thick ( somewhat like my head ) that you would have to really try hard to offend me.

Very sorry you got that treatment. It does not gell with the Victorian members that I know however I might just send your reply down to the appropriate committee member.
If any one comes away from a meeting with that feeling it is just not good enough.

Next I have just retired as secretary of the NSW BSAMCC so it is not a problem that I take personally.
I still emplore you to come along to the All British Rally where you will find quite a few M20 owners some of which will bend over backwards to get another one back on the road. Worst you could do is have to sit with me all night drinking some nice red ( no cookies this year ).
Being a side banger these motors are so simple to work on it is not funny.
I have never had much luck getting the crank true but the local Ducatti shop wacked it together while I waited and had it true to within .0005", he said it was a lot easier than doing a Duke.
Other than that I do the lot. and most of my work is done in a dirt floored open machinary shed.
The single spring clutch is a PIA but I have one of Ron's Clutch tools on the way replacing a BSA tool.
While measurements need to be a bit tighter than a frame truss you can get by with nothing better than a vernier with digital readout ( eyes are not getting better ) but a couple of micrometers would be better.

The bikes are a lot more robust than many would have you believe.
The only bolts with critical torques are the crank journal nuts. Other than than it is 1 grunt or 2 grunts of torque.
A ( now deceased ) member was in NG during the war and he had stories of whipping off the barrels by the side of the road to clean the fused coral dust ( road making material ) off the top of the piston and head with a screwdriver and some times just a sharp rock , bolting back the barrel with nothing more than the tool kit supplied ( if it had not been stolen ) , oft either in the dark or pouring rain.

The biggest problem is getting you head around the fact that these are not high performance modern engines that self destruct if a 0.001 micron dust particle comes withing 20 meters of the open engine.
They are a very simple, very basic design from the 30's over engineered to make them just about indestructable and totally idiot proof which is why the army used then in the first place.

email (option): wariron@tpg.com.au

Nick your older than you think, that was over a year ago.
How did you get on with magneto??
Libarian, how there are no books left.
Are you doing a custom M21 as the front brake plate and rear hub aren't right.
Thanks for the offer

Cheers Darren

email (option): Darrenacartwright@yahoo.com.au

Trevor
I work with an ex commitee member, so if it really bothered me I would have said something.
I can't make it to most meetings due to work and family.

I have tried to get to the rally twice but again work etc get in the way, plus my R6 would not be welcome.
Red? How about a Coopers. That might twist my arm.
A friend goes and gets the odd photo of Wm20's for me but that's about the closest I have been.

Cheers Darren

email (option): Darrenacartwright@yahoo.com.au

Julian
I have been watching your thread with great interest, and a little jealousy
but thank you for the encouragement

Cheers Darren

email (option): Darrenacartwright@yahoo.com.au

Darren, Bugger, I must be getting old, i'll be half way to 50 in April, over the hill already I guess! As much as i'd like to I simply can't possibly afford to restore the bike to original spec so i'm using a spare Goldstar 8" front brake and the rear hub is a unit 650 Triumph set up i got for peanuts, they're much easier to get parts for and have a bolt on sprocket. i've got some new Ferodo brake pads for it and they have a simple speedo drive off the side which opens up the option for a repro Triumph speedo on the bars in KM/HR because I can't afford a Smiths. so far I just have an M01 maggy body and an armature for the generator, still looking for the rest, complete units go for insane money so hopefully the Swapmeets coming up will turn up some parts for me. catch you round mate. Nick

So Gents
I have decided I HAVE to do it myself, I NEED to learn.
Where would you start
Is it a matter of balancing the flywheels, pressing in the bearings etc
Can someone please advise of the correct order
Thanks

email (option): Darrenacartwright@yahoo.com.au

Hi Darren..Unless you have someone with the right equipment to show you how to do it I would still get the crank reassembled and trued up by a proffessional...Then you can start on rebuilding the bottom half of the engine. Also get a copy of the original BSA factory worksheets...I think Henk has these for sale on a disc...You need to be able to go through these sheets to get a good outline of how to do each part of the job...
If you have a grasp of the basics of each stage THEN you can hit the forum with particular questions...To write a post describing how to put an engine together in detail would take days.
Broadly though, for the bottom half which you can treat as the first part of the project...
Get the flywheels rebuilt.
Obtain all the new parts you require (bearings,gaskets,seals any new fasteners needed etc.)
Prepare all the parts...clean everything thoroughly, make sure there are no damaged threads that need repairing, deburr the gasket faces, crankcase joint etc. etc.
Check the oil pump for free rotation..it should be free to turn by hand.
Check the oil pump drive shaft fits freely into the crankcase.
Check that the main bearing spacer on the drive side is within limits (1.000"-1.005" long)
Check that the drive side oil flinger plate is flat and unworn.
Check that the faces of the cam followers are not worn beyond limits, are not damaged where the tappet heads screw on and fit freely through the tappet guides.
Check the tappet heads where they contact the valve stems..they should be flat. If there is a recess worn in the working face replace them.
Check that you have an undamaged bearing retaining clip for the drive side crankcase.
Check that the crankshaft pinion is a sliding fit by hand over the timing side shaft...then repeat the test with the sliver key fitted. If in either case the gear is too tight to fit by hand you will have to do some work achieve the right fit...DO NOT knock it on with a hammer!
Check the fit of the magneto drive oil seal in the crankcase recess..The recess should be unworn, and round ideally. The seal shouldn't 'fall in' to the recess freely...
Arrange a clean a well lit space to work in where you can lay out all the engine parts.
If you can't use the oven in the house you will need a heat source to warm the crankcases before fitting the main bearings, the intermediate gear and thrust washer and the cam spindles (assuming you have removed them, you should have if you had the cases blasted.)....
After all that you are pretty much ready to start assembly....Ian

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

Thank you Ian
I will get the disk from Henk
I have NOS cam spindles,cam followers, cams, con rod,oil filinger , shims, bearing clips, new bearings(Austrian) not Chinese .
I have access to a hydraulic press and an Ex so the ovens all mine.
I intend to get an new oil pump body CNC'd out of billet aluminum .

So I suppose my question is if using all new parts, it is a straight forward as re assembling , after the flywheels are balanced?

Thanks Darren

email (option): Darrenacartwright@yahoo.com.au

Ian,
I have an original copy of the service sheets is this what you refer to?
Darren

email (option): Darrenacartwright@yahoo.com.au

Yes, that's it Darren...You won't need the hydraulic press...All components can be refitted to the cases using heat,a hide mallet and suitable punches and a knocking stick...Ian

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