Re-commissioning my '51 4G

[adrian.hannam]

My purchase arrived from interstate a few weeks ago, but I wanted to buy a hydraulic bench before making a start. The homemade bench I have been using has been great, but I just can't manage the bigger bike up onto it, by myself, in my small work room. Here it is.

I have bought a 1951 4G. It will be known by some of the members of this forum. It came with log books of all trips covered since 1992. In South Australia, to keep historic registration you need to keep a log book. The last owner bought it in 2002 and due to illness in the family, only covered 5 miles. So I am destined to inspect the crank. The good news is that the engine was rebuilt 1200 miles ago, It has an oil filter installed, so I expect it to be in good shape. I have read all the literature and followed many posts on this forum, so I think I know what to expect from the job. The box of spares has old pistons, rings, valves, bearings etc and an Otto pamphlet so I'm hoping there won't be much to do. The bad news, well there isn't any really, except for cost. Besides that I'm a pretty average mechanic, but getting better with practice. I'm considering new rods, it will need new silencers, tyres and rubber parts. I will pass on a Morgo for now. There is a plunger pump in the spares box, so maybe there's a morgo in there already! Maybe a Longman alternator in the future would be nice. Aside from that Im' hoping it should be straight forward. I'm not too concerned about cosmetics, it just needs to be safe, reliable and tidy. I do live in a hot part of the country so I am a bit concerned it will only be a winter bike, but we'll see. It has a 1951 VH and 1948 KG for stablemates. Regards, Adrian.

One of the first anomalies is a breather from the rocker box cover to the carb air intake.

I haven't heard of this mod being done to a MK1, it there any advantage?

[nevhunter]

If it's a paper filter element it won't like the oil mist, otherwise it's not an unusual procedure. New rods on any unknown 4 are probably good insurance. Alloy rods in any situation have a more limited life than steel ones. Of course have the crankshaft(s) been cleaned properly? That is the question. You don't have to be Einstein to work on a square. The drive gears should be tight on the shafts to do their job properly and you don't have to align the cranks like a built up one requires. Good luck with it. Nev

[adrian.hannam]

Started it for the first time tonight. Didn't run for long only 20 seconds or so, conked out when I touched the bi-starter, but a major milestone reached. 45 psi oil pressure indicated. Tomorrow, see if I can get it to idle with the starter off. Need to make sure the battery is charging and reverse the ammeter connections. After that, re-tension the head.

[paul.jameson]

Whoa there Adrian !

You don't know yet whether the sludge traps are clean or not. You do know that if they are not, an engine blow -up is imminent. So take the timing cover off and look inside to see how clean it is. If you could eat your dinner off it, then risking running the engine may be ok. If it is filthy, then don't run the engine before stripping it to clean out the traps. With the timing cover off you will see whether a Morgo pump is fitted or not.

Re-torque the head? What torque settings will you use? Anything more than Bruce Longman's lowest figures risks stripping the threads of the head studs. How are you going to measure the torque? If the engine has been assembled with Otto gaskets which have been re-torqued correctly at the right intervals, you shouldn't need to re-torque.

As Nev says, the Square Four is not difficult to work on, but it is delicate in the areas of sludge traps and alloy threads.

[adrian.hannam]

Way ahead of you Paul. the first post is almost 2 years ago. I just haven't been using this post as a blog. I prefer to make single topic posts, I reckon it makes things easier to find later. In the meantime I have refurbished the gearbox, stripped the engine, cleaned everything, vapour blasted the cases, installed new rods, Otto gasket, oil filter, Longman alternator, and rewired. I have taken note of many of the tips and improvements from this site.

Most stories on this forum involve previous owners doing bad things to Ariels, and the new owner fixing these horrors. So I decided to do the same. The ironic thing for me is that I am probably the worst mechanic ever to put a spanner on this example. Oilways were clean, for the most part nothing was broken, no nuts were rounded off, threads were good, it had an Otto, and a remote filter. I could have been riding it straight away.

I have the head torque settings, I use a torque wrench where I can and a spanner and spring balance elsewhere. One thing I am not happy with is the cam, discussed in another post. It appears to have been ground at a new angle to the keyway, and the valve timing is retarded.

I expect fettling and tuning to take some weeks or even months.

Total amount of soft sludge which came out.

Daylight.

I'd eat off them.

[paul.jameson]

Lovely - I am much relieved ! It will tech me to look at dates of posts.

[david.anderson]

Adrian
Congratulations and I hope you enjoy it. My square is generally only used in the winter when it is a nice leg warmer, but in the summer the hot air off the engine onto the rider is most unpleasant. At the Highfields rally at each stop you could have fried an egg on the engine or oil tank of my 4 for that matter. After that my 4 became a winter bike.
The air filter that has been fitted to your 4 is probably too restrictive. I fitted the same paper element filter to my VH (which at the time was running 10.5 to 1 compression). It caused the engine to overheat and knocked 20mph off the top speed. I threw away the paper filter and have subsequently used the filter shell on my 4 but it is now fitted with a foam filter instead. Also the 90 degree bend from the filter to the carb also reduces air flow unless it is a lot large than the carb bore size.
David

[nevhunter]

IF it's any consolation, I think that model is the best looking of any. I understand there's some question about the quality of the castings around that period and I guess you take your chances on that one.. Good luck with the challenge. They are not new anymore. I've ridden a lot of bikes but only one square a 48 rigid and it was original low miles. Nothing equalled the smoothness of the engine and the acceleration to about 45 MPH. Nev

[paul.jameson]

I did some work last year on a Mk I for a Club member and the engine was a dog's breakfast to say the least. After a complete engine rebuild, I had to do some miles on it before returning it to the owner and to my continued annoyance it remains possibly the very nicest Square Four I have ever ridden.

[simon.holyfield]

Why did you like that one so much Paul?