SQ4 - all done

This might be the last post on the Square Four for a little while - it's next trip is likely to be to my long-term storage at my son's house, where I shall go to collect W/NG to come back for some work - but more on that later .

Today I took the Square on a 15 mile round trip to Cromer to do some painting and do the final shake down on the carburettor and ignition settings. Yesterday I fitted the new mixture screw and this needed a little bit of tweaking to get it spot on and I increase the idle speed slightly - though I think I've got it too high. I also retarded the ignition slightly. 

The good news is that it's running very well. It starts easily and it will pull away cleanly in traffic from low speeds. It flies along on the open road so all in all I'm very happy.

Here it is resting at Gresham church.

Getting home, it occurred to me that in a similar fashion to the light switch yesterday I had not touched the horn for a long time. Since I fitted this horn, which came straight from eBay, I don't think it's had any work done to it and as regular readers will know I've become reasonably adept at adjusting these horns.

I gave this one a little tweak to make the sound a bit more intense.

SQ4 - idle mixture screw

 I recently took a punt on an eBay sale for a mixture screw for a carburettor from a Rolls-Royce B40 engine, the one used in the Austin Champ. It was listed as a Solex part and looked very much like the one on the Square Four.

I struck lucky - the parts are exactly the same.

This is the old one, and measures 4.86 mm at the end of the thread

This is the new one, which measures 4.92 mm at the end of the thread:

So perhaps not a huge amount of wear. It does appear though that the nose of the old screw is notched - I don't know if you can see it in this picture:

I fitted the new screw with a t-bar and put it back in the carburettor with a wrap or two of PTFE tape. 

We'll have to see if it makes a difference.

SQ4 - dodgy connections

 Riding home a couple of days ago in rather poor light I became aware that the headlamp had turned itself off. A few minutes fiddling with the light switch made me realise that there was something going on with the contacts - I could wiggle the handle and the light would flash. This needed further investigation.

As far as I could tell from various blog posts, this original Lucas U39 light switch had not been apart for probably 10 years. My own skills and knowledge have improved immensely in that time and I now clean these switches with an ammonia based clock cleaning solution as shown in this post. 

The one on the bike was clearly a bit grubby. 

I stripped it out and immersed it in a 25% solution of ammonia-based clock cleaner for about 4 hours.

After a few hours, the brass parts emerge without the tarnish and looking a lot more and conductive!

Here it is again, reassembled.

Charlie's Shed - tool restoration

 I've done a lot of posts on toolkits and tool rolls in the past, and here comes one more. Repacking the Huntmaster toolkit one day I noticed that a 3/8 BSW spanner was rather damaged - in typical fashion it had been sprung open by over exertion.

It's actually quite easy to fix these. I set it up in my little hearth and heated it cherry red, picking it out with a pair of tongs and giving it some adjustment with a 1 lb hammer. It's actually closed up nicely back to size.

The black finish is achieved by quenching it in oil.

SQ4 - idling again

 A 30-minute run out this evening confirmed that adding PTFE tape to the volume screw put us on the right track to improve the idle and hesitation problems on the Square Four.

It needs more work, adjusting the idle speed down, further adjustments to the ignition timing and probably some small changes to the idle mixture as well but it is starting well and idles smoothly.