Ariel Owners Motorcycle Club

Has anyone got any pointers as to what to look out for when purchasing a Square 4 mk1. I am look at a prospective purchasing at the end of the week any help gratefully received thanks Mark.

Moved!!!!
(Not help with the Forum, but somewhere for help from the Forum...... )

SG

Hi Mark,

There are a variety of things to look out for, most notably the below in my opinion:

- when was the engine last rebuilt, and is this verifiable via invoices/receipts/photos
- have the conrods been replaced with new ones?
- is it running a remote oil filter on the return line?
- what sort of oil has been used in the tank (detergent oil mixed with no remote filter is a recipe for disaster)
- when were the crankshaft oil galleries last cleaned out?

None of this is a deal breaker, but you will need to factor in the cost of rebuilding the engine if none of these questions are met with satisfactory answers.

There is a lot to talk about regarding originality, but that is not important to everyone. If you see one you like the look of, it is worth posting a link on here as you will receive good critique/advice.

Good luck!

Thanks for the guidance have bought a nice Mk1 1950 need a little cosmetic wok has been running on single grade castrol oil was rebuilt back in 2018 new pistons bearings etc, sludge traps cleaned but not rods, some say the rod thing to not a problem some say its is so does worry me a little. I am worried about doing a rebuild to put rods in as an insurance policy and have seen a chap in the US has fitted a remote filter in the return feed and used a 2CV Citroën remote filter housed in the tool box is this a good idea, and once rebuilt is mult grades like penrite 20w70 that people US in Australia for beter high temperature protection? Sorry I am a classic Mini guy and only no what little I have read on the ariel so there will be questions I already have a workshop manual etc and have my late father's bsf tools

The oil filter is a must with those engines. Mine is underneath the gearbox and quite hard to spot!

Draganfly do a kit:

https://draganfly.co.uk/shop/57889/squa ... t/#1521-92

There some pictures of my installation:

https://ariel-square-four.blogspot.com/ ... r.html?m=0

Welcome aboard! They are great bikes. Show us some pictures!

I am a little worried by your reference to "single grade castrol". Is this normal mineral oil of say SAE40 or has someone been running the bike on Castrol R vegetable oil? If it is Castrol R then your engine will require stripping completely and cleaning to immaculate standard, along with the oil tank and pipes to remove all traces of the Castrol R before you can change to normal mineral oil.
I am working on a Square Four engine which has seen use of Castrol R without being properly cleaned first. There is a glue like substance coating everything which is only removeable with cellulose thinners and a brush at least or preferably a scourer.
Hopefully, it is normal mineral oil which has been used in your bike but I feel I have to give you this warning.

I have a oil filter on order with dragonfly the oil that's in there is a straight mineral not castrol R as you cans smell the ricin. Once I have the oil filter on i assume it will be OK to use an oil with a detergent ans was look at penrite enduro 25w70 as thats what Penrite recommended and penrite a good oil as used the penrite transverse stuff in a souped up mini. Next question are morgo rotor oil pumps a recommended upgrade? Thanks for every one's help so far cheers.

I am relieved to hear that you don't have the problem of Castrol R. It is an absolute horror.

As to Morgo oil pumps, I have never felt the need or inclination to replace an Ariel plunger pump with a Morgo one so unless you have a major problem with your present pump, I would leave well alone. On the other hand, I would never run a Mk II Square Four without replacing the original oil pump with a Morgo one. This is because the original gear type pump on the Mk II is notorious for failing by reason of distortion of the very poor mazak body. I believe the use of this pump might have been a bright idea from BSA but they are well past their sell by date.

So iron 4G and Mk I, stick to the plunger pump. Mk II throw the gear pump in the bin and fit a Morgo one.

Yeah I remember my late uncle who was a mechanic complaining on how some has mixed Castrol R with mineral it throths up and the bearings end up getting striped. The bike has good oil pressure and the return flow to the tank is good so I take you advice ans stick with it. Mu background is cars an mainly classic minis ad the have no end of problems with metal getting in the pumps but least these bike have separate gearbox. I going to fit the dragonfly filter ans also put something called a filter mag on the canister, the are an arched plat of rare earth magnetic the pull metal particles out the oil down to one micron. I sell them at work there really good, I have used them on my daily drivers for the past 15 year's. My old vauxhall had 160k miles on it and was still pulling like a train and never burnt a drop of oil, I put this down to regular oil change and the filtermag.

Magnets are good especially with a gearbox sharing the oil I fit rare earth ones to the drain plugs and they'll work through the canister wall (spin on).
You can cut the spin on open to check for metal if you're fussy. I think it's worth while particularly with new motors Nev