Square four mk1 frame

Singles, twins and fours.
FletchBurton
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Re: Square four mk1 frame

Postby FletchBurton » Fri May 22, 2020 10:42 pm

Ok so the puller has now arrived from Drag for the connecting gears so I will continue the engine strip to get to the sludge traps. This will give the access to the rods and big ends for measurement and inspection. After that it will be to decide to use the club rods on this engine or save them for the 4g I got at the weekend. Looks like I got bit by the sq4 bug then.

FletchBurton
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Re: Square four mk1 frame

Postby FletchBurton » Fri May 22, 2020 10:58 pm

Also FWI I got a MK1 frame complete with plunger assay and head stock and all casting/lugs inatct for 750.

T.J.Falloon
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Re: Square four mk1 frame

Postby T.J.Falloon » Tue May 26, 2020 7:44 am

Hey Fletch,
Welcome to the group and good luck with your restoration project.
I have a '51Mk 1 Sq 4, which I have recently got back on the road. I would not have been able to do this without the support and infinite knowledge of all here on this site.
I completely stripped my engine , cleaned out the sludge traps and fitted new rods from AOMCC, which are beautiful pieces of art in themselves, and all new main bearings. I bored my barrels to first oversize and fitted OTTO head gaskets.
The only other cautionary advice I can offer other than the normal ones most everyone here has spoken about, is to make sure that you lap your crankcases together properly so you don't get any oil leaks. I had to re-strip mine after getting her back together due to an annoying oil leak. I took my crankcases to my engine reconditioner and had this done. You could do this yourself but I didn't have a large enough flat surface to do it on.
I still have a couple of little issues to sort, mainly carb related but the engine is running sweet as a nut.
Take your time, it is totally worthwhile at the end of it all and continue to ask questions if unsure about anything.

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john.bebb
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Re: Square four mk1 frame

Postby john.bebb » Tue Jun 02, 2020 7:24 am

Seem to recall some few years back a club gent created a batch of swing-arm frames for Sqs - might be worth searching for one of these 'cos at least then the machine might handle..!

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simon.holyfield
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Re: Square four mk1 frame

Postby simon.holyfield » Tue Jun 02, 2020 9:47 am

john.bebb wrote:Seem to recall some few years back a club gent created a batch of swing-arm frames for Sqs - might be worth searching for one of these 'cos at least then the machine might handle..!


How do you find yours handles John? Mine is not too bad (or so I thought), but is much less steady than my rigid W/NG. The SQ4 does not corner so easily as a more modern bike, you have to steer it more, and tramlines a bit. Mine wears 7 year old Avon Speedmaster/SM Mk2.
cheers

Simes

'51 Square Four,
'58 Huntmaster,
'42 W/NG,
'78 CX500
http://ariel-square-four.blogspot.com

FletchBurton
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Re: Square four mk1 frame

Postby FletchBurton » Tue Jun 02, 2020 10:26 am

Hi.
While I was looking for a frame I did indeed come across a swinging arm frame modified to take a square four. It was in a shed near Boston Lincs.
I think he said it was an Ariel twin frame.
Fletch

will_curry
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Re: Square four mk1 frame

Postby will_curry » Tue Jun 02, 2020 2:21 pm

As far I as understand the rear wheels on Squares are built differently from
others - the offset is different. It might be worth checking if you haven't already.

My limited experience with a Mk1 is that it does 'feel' somewhat strange which
I've always put down to two cranks spinning in different directions and thus unusual
gyroscopic effects.

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john.bebb
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Re: Square four mk1 frame

Postby john.bebb » Wed Jun 03, 2020 2:39 pm

Hi Simes - "How do you find yours handles John?" - well as you imply... certainly NOT like a modern machine! - from ~1975 through to 2018 I owned various BMW boxers from the R90S upwards.. to which in comparison the Sq definately does NOT handle...
but treat the Sq as the 70 yo which it is... the handling is still not too impressive - for me the two big downers are 1/ the brakes & 2/ the Anstey tail... (possible #3/ - it's also got pathetic ground clearance wrt the footpegs)
1/ was easily remedied by a 9" 4ls Grimeca - (zero mods to original forks) & with that at the front the rear becomes virtually irreleveant.
2/ the Anstey was designed for one purpose only; - to minimise variation in chain tension - it's quite effective at this task but fails miserably at suspension & handling - the tail can wander & become very sloppy if the various bushes are not a/ adjusted & b/ greased regularly... the snail cams which were original on my '49 were replaced by use of the later screw adjust Anstey fork which I find far superior.
My current rebuild will include a taper headset - I hope such may improve handling a little. - Will let you know when it's back on the road but with most peoples running at snail's pace under the auspices of Covid issues - that may be a few months yet!
Not sure what tyres I've got on currently... nor what pressures I'll use - as such will be set heuristically.
We should all remember that over the years there have been vast advances in tyre construction...
Cheers, John

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Re: Square four mk1 frame

Postby JohnnyBeckett » Wed Jun 03, 2020 4:34 pm

HI you can not compare modern bike with a ridge or plunger bike the back end will jump around some of my younger friends have built hard tail bikes like mo ones and i told them you will not like them because they Handel a lot different and two of them have sold them now and i told them you can not go tear arsing around like you do with your later motorcycles :!:

david.anderson
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Re: Square four mk1 frame

Postby david.anderson » Thu Jun 04, 2020 1:27 am

On the subject of handling of the 4, any handling issues can be sorted by sorting out the suspension. The front damping is inadequate and the rear is undamped. I have fitted cartridge emulators to the front forks which provide proper, adaptive 2 way damping which is equivalent to any modern bike, and I have fitted friction dampers to the rear. Suitable friction dampers were detailed in an article in Cheval a few years ago. The friction dampers are 2 way damped, and surprisingly need very little tension to be effective. The bike has been completely transformed. I have reset the footpegs to give more cornering ground clearance, so now the limiting factor when cornering is the mufflers drag.
Braking, I made a twin leader for the full width hub, fitted and turned oversize linings to fit the drum, which is a big improvement over standard. I never could figure out why Ariel fitted an 8” brake to rear of the MK2 instead of the front. The Rear 8” brake is however as good a rear brake as any.
The square 4 was designed as a tourer and with minor suspension improvements is ideal for that purpose. But the 4 will never run with a swing arm single.
David


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