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Square Four MkI - first rides after restoration

Posted: Mon Jun 17, 2019 10:24 pm
by Gui.dorey
Hi Chaps,

Decided to start a new thread after the woes with engine, and having rebuilt it for a second time, to report on the first experiences running the Square Four in.

Today I went for a longer run to get get the engine up to normal running temperature, set my idle, set the air screw on the carb, check for leaks, and to get a general feel for how everything is running.

She starts now on about the second or third kick with the bi starter in the mid position. Since she would die if I closed the bi starter all the way, I raised the throttle stop a bit and also screwed the air pilot 1/4 of a turn in, and it got better. Still can't shut the bi starter completely, but getting there. Problem is, when she is warm you can't really get in there to adjust the throttle stop without burning your paws. Will have to fiddle with it some more though.

I took it really easy, maybe 80-90 km/h tops, and she shifts fine throughh all the gears. She pulls fine with good acceleration, although the engine seems a bit harsh on top gear, so I'm not sure if it's normal or just the running in phase. I also am getting some vibration on the handlebars coming from the engine. Oil pressure still on over 100 psi when cold, but kept going down as it got warmer, and when I arrived back home and was playing wih the idle the needle actually went down to near 0...???

The only big thing that's bothering me are the oil leaks. A few minor ones from the primary case, but I had the back wheel on the right side slathered in fresh oil! After rolling on the ground like a bug on its back trying to find out where so much oil is coming from, I believe it's fom the timing chest's breather. Now I'm not sure if this was due to the initial high pressure I was seeing, or due to something else. Still, it seems like a lot of oil is beeing pumped into the timing chest.

A major leak is however coming from the gearbox output shaft. That seal is apparently not doing its job, I'm afraid. Other than that I also noticed one tiny spot behing Nr 3 where the otto gasket is not sealing. But after the first run, I will have to check the torque on the head nuts anyway. The only two I can't really get to are the ones below he inlet manifold. Somebody has to show me how you actually get to them and turn them down.

Otherwise the only thing that is not working properly is the speedo. It actually seems to have been serviced by the previous owner and in very good condition, but the needle jumps a lot up 70mph (and I was definitely not doing 70 for sure), sometimes it gets ramdomly stuck and then jumps again, and finally gets stuck between 65 and 70 not going beyond that spot until my speed is much lower, at which point it jumps back down again. Any ideas on what I could check or service on my own, before I send it somewhere for repairs? It might just be something simple from just sitting around for years.

I'll keep you posted on further progress.


PS using a morgo pump and oil is happily and plentifully flowing back into the tank.

Re: Square Four MkI - first drives after restoration

Posted: Mon Jun 17, 2019 11:39 pm
by simon.holyfield

Some folk solder a tee bar on the idle mixture screw to make it easier to get to without burning yourself. I made a short bent screwdriver for the same purpose.

I have two fibre washers under the float valve now. Before i did this, I could come off the Bistarter after maybe 2-3 minutes and I needed B5HS plugs to keep them clean; now its about 10 minutes and I am back on standard plugs. Be aware that making the idle too weak will leave you with a flat spot as it comes off idle...

Secondly, my bike has a few oil leaks; at some point the head will have to come off again as I failed to seal the pushrod tubes properly. Others that I have fixed include those fibre rocker cover gaskets - the engine gets too hot for any fibre gasket at the top end. I have threebond up there now which is a lot better; use a copper washer on the rocker oil inlet to fix that one - i'm getting around to fitting alloy washers (or maybe copper) on the rocker shafts too, though I don't have more than a weep there. The rocker box leak used to make a hell of a mess, all over the oil tank and distributor. it led to a misfire as well, until i realised the oil was in the HT connections on the dizzy. I have a big rubber sock over that now.

Sorry if I have asked you this before, but do you have the rocker oil feed pipes the right way round? big one to the gauge?

On the speedo, I think the clutch is greasy. Easy to fix if you like watchmaking, but I have pretty much given up tinkering with them now. I get such good service from Russell at Chronometrics in Nottingham that its foolish to risk playing with something I'm not expert in. Same story with magnetos!

Re: Square Four MkI - first drives after restoration

Posted: Tue Jun 18, 2019 3:48 am
by pauldridge
Hi Gui,
I am pleasantly surprised to learn you have recovered from the too-tight end float so quickly, and congratulations on getting the old gal back on the road. As Simon and others suggested, I soldered a small bit of brazing rod into the slot on the air mixture screw. I was able to find a rod of almost perfect diameter, sort of pressed it in, and then soldered for good measure. It was an invaluable modification, as it makes it really easy to turn the screw when hot with a hooked pick of some sort.

As far as the head bolt re-torque, my guru Paul Ackerman, insisted that I retorque the head after just a single initial 10 minute static run of the engine. This includes ALL the head bolts. I was really surprised to find how much the torque had loosened with just that short run.

In my opinion, you should resist the temptation to bypass the headbolts under the intake manifold. Once you get the hang of it, it is a 5 minute job to:
1) remove the external oil feed line fitting at the front of the engine only (so you can pull it back a bit to allow the intake manifold to come off)
2) remove the dizzy cap for better access
3) remove the two carb nuts and take out the Solex with bistarter intact
4) remove the intake manifold

Paul's directions also insisted that the 4 head sleeve nuts in the center (the ones holding down the rocker towers) need to be retorqued as well, and that, unfortunately, gets really tricky with the rocker crossfeed pipes in the way. Paul installed a modification on my rocker towers that involved drilling and tapping the rocker oil transfer ports, then using brass compression fittings and a small copper line for the oil transfer. This allows quick and easy removal of the crossover for easy access to those head sleeve nuts. Of course, it's a little late for that mod for yours. The photo also depicts the modified valve adjusters Paul sells, which use a hex head/Allen adjuster stud to make the adjustment process easier.

My own engine now has just a bit over 800 miles on it. during that period I retorqued all head/barrel nuts, changed oil, and adjusted valves at:
10 minutes initial run
50 miles
300 miles
800 miles
The filter was changed at 300 miles

At this point, I think I am done, save for oil changes every 1,000 miles or so (which will likely be about once a year for me!)

Some of the recommended intervals seem like overkill to me, but after all this work and expense, I don't mind a little busywork and a few quarts of oil to protect my investment!

Re: Square Four MkI - first drives after restoration

Posted: Tue Jun 18, 2019 5:38 am
by Gui.dorey
Thanks Phil,

The head bolts at the front under the oil line as well as the four inside the rocker boxes, I can get to. The trouble are the 2 at the back under the manifold. And unfortunately, on the MkI the manifold cannot be removed. Its part of the whole head casting....

I also have a short wire soldered on the pilot air screw, which is great. But I meant the screw for the throttle stop. I usually play with both to get a stable low idle. This is hard to do easily on the MKI because everything is so tight in there.

Re: Square Four MkI - first drives after restoration

Posted: Tue Jun 18, 2019 6:34 am
by camstevens
Hi Gui
Regarding primary oil loss....without exaggeration, my bike would dump the entire primary oil out the shaft entry hole with 1min of running.....I bought and fitted aluminium thrower discs (purchased from Peter Kemp), which have proved effective....a fair bit of case fitting, removal and refitting as the discs were contacting a little. That bit can drive one a bit ga ga, but worthwhile. See pic attached. You can see the 2 discs riveted either side of the chain wheel.

I am also getting some vibration on handlebars at higher revs......this may be partly derived from my primary case woes, but I think more to do with mixture......more fettling this weekend!!


Re: Square Four MkI - first drives after restoration

Posted: Tue Jun 18, 2019 8:48 pm
by paul.jameson
I have to agree that the nuts under the inlet manifold on the Mk I are an absolute sod to get at. See if you can source some nuts with 12 corners instead of the usual 6. This doubles the chances of getting your ring spanner on - which caters for 12 corners. But do remember the golden rule on a Mk I which is not to overtighten the head studs or they will pull out of the alloy as soon as they can.

Re: Square Four MkI - first drives after restoration

Posted: Wed Jun 19, 2019 8:15 am
by Gui.dorey
camstevens wrote:Hi Gui
I bought and fitted aluminium thrower discs (purchased from Peter Kemp), which have proved effective

That sounds like a good idea. However, it makes you wonder how did they work as new - did the customers of a brand new and expensive Sq4 just accept that the primary case oil spilled out? if this didn't happen, then what did Ariel do differently from our restorations decades later?


Re: Square Four MkI - first drives after restoration

Posted: Wed Jun 19, 2019 8:58 am
by simon.holyfield
How much oil did you have in there Gui?

Re: Square Four MkI - first drives after restoration

Posted: Wed Jun 19, 2019 9:22 am
by Gui.dorey
simon.holyfield wrote:How much oil did you have in there Gui?

Just filled it up to the level plug. Should be correct, right?

Last evening I checked the torque on the head bolts. None needed retightening, but another question arised. Should I ease all the nuts and then re-torque, or is it fine to just check the torque and retighten as they are? Only the two under the manifold are impossible to check at the moment.


Re: Square Four MkI - first drives after restoration

Posted: Wed Jun 19, 2019 9:54 am
by simon.holyfield
Conventional wisdom is to put enough in to just wet the chain. Fill it up to the level plug and it comes out... I do it like this and it doesn't seem to be a problem, but I do check it pretty frequently (weekly). You will have seen a few broken primary cases on the forum I bet!

I'll leave others to comment on torquing practice. I don't slacken first, but then every time I have done this I have not found the nuts very tight. All my head studs have inserts, by the way.

I have a very short (5"?) ring spanner for those two reduced hex nuts under the inlet manifold. It's a small 12 point cranked spanner and I can just get it in, but as you say it is very difficult. If I had two, I'd consider bending them in opposite directions to make it easier. It's not helped by the fact that the casting was not cleaned up very well around those nuts and the clearance is very limited.

I will introduce it to the Dremel when I next take the head off.