Monthly Archives: August 2024

TIMING TOOLS

Leave a Reply

I recently bought myself a new toy, an LE Velo which was part restored but complete.
It’s a a bit of a mongrel as it has a MKII chassis fitted with a MkIII power train and this has led to some problems.
As I got it it was a runner, easy starting but totally gutless, I had had an LE some 50 years ago so I knew the performance to expect and this was nowhere near, it was down to about Cyclemaster levels!.
As there was a lot of free play at the twistgrip I went to check that I had full opening at the carb and encountered the first “Gotcha”, the coolant hoses came away from the stubs at a touch, yes the stubs were rotten!
This brought about another problem, I now needed the correct Imperial sized spanners so it became trips round the autojumbles to get the spanners needed, although I did also find a couple of (expensive!!) sources on the internet, then it was dismantle and remove the cylinders and get new stubs fitted.
I joined the LE Velo club, sent down for gaskets manuals etc and the rebuild started.
There were no difficulties until I learned constructive use of foul language when I came to setting the tappet clearances, accessibility with the engine in the frame is, er, a little limited shall we say!
Anyway with the engine back together I finally got round to the carburetter and found I was not even getting half throttle at max, and all adjustment had been already been taken up.
On looking in the spares lists I found three different cables listed, which was the correct one?, and remember my bike is a hybrid!
So I took the easy way out and made up my own cable, including a mid-way adjuster, which was just as well!.
This was when I discovered the delights of the MKII LE throttle assembly!. I must admit it suits the bike better than a modern quick-action type would but it is a surprise when you first encounter it, an involute scroll is not a common system!.
OK, time to fire her up and see what’s what. Fuel on, choke on, a quick tickle, kick her over a couple of times to prime the engine, switch on and kick and the little lady’s running, talk about an east starter!
Rev her a couple of times, and find she would not rev free and was not running well.
It was apparent that the timing was out. So check the book on how to do it.
Book says – “Set to TDC by centring the mark on the flywheel in cut out”, fair enough but something did not seem right and a quick screwdriver down a plug hole showed the piston was not at TDC.
Checking the books and I found that the flywheel is not keyed in position and that, electrically speaking, the flywheel alignment did not matter, the marking was only to allow for easy timing and that as long as the points opened at TDC, having the marks out only meant that the emergency start facility would not work. From previous experience of these “emergency start” systems this did not worry me!
How to find TDC?, it’s easy. You just drain the cooling system and remove a cylinder head! sacrificing some coolant and a new head gasket in so doing!
There must be another way, thinking cap on!
The best way to find TDC is by using a piston stop, how to do this on an LE though??.
On a OHV machine you can poke something down the plug hole, straight down onto the piston but the LE is a side-valver, the plug is to one side and at a shallow angle. I had a spare head so I got this out and had a look and then went out into the workshop.
I had a length of 15mm brass hexagon bar in stock so this was chucked up in the lathe and one end skimmed down to 10mm OD for 43mm.
This was again skimmed down to 9mm diameter for 33mm so I now had a stepped rod with a hexagon head.
The top, 10mm diameter, length was then threaded 10mm x 1.0mm (10mm spark plug
thread) and all this gave me the desired piston stop.

    Piston stop

I tried this out in the spare head and it showed the end of the bar protruding to about 10mm below the lower surface of the head above the piston, IDEAL, just what I was looking for.


Piston stop in head

Showing stop protruding below head.

Next I needed a mount for a degree disk.
I could not mount a disk direct onto the end of the crankshaft as it would foul on the ignition coils so it was back to the stock box where I found a length of 30mm diameter aluminium bar and that went into the lathe.
I turned down the end to give a 1mm high stub of 15mm diameter, intended to fit neatly into the centre of an old CD disk.
I next drilled a 4mm hole about 35mm deep down the middle and parted off first a 25mm length and then a 5 mm length.
I tapped the hole in the longer piece to 2BA and opened that in the shorter to 5.5mm, this gave me the stand off mount I needed.
My intention was to stick a degree disk onto an old CD so my next step was to download a picture of a degree disk from the Internet.
I printed it out on card to 125mm diameter. I then found this was too big for the CD and decided not to bother using the CD after all. So I cut the disk out, made a 5mm hole in the centre and I was all set.

  

 Disk stand off parts

Bike up onto the bench and raise rear wheel clear of the deck, front cover off, remove centre bolt from the advance unit and replace it with a short length of 2BA studding. Next was to thread the longer of the ally stand offs onto the studding and wind it down till it was in contact with the advance unit.

  Disk standoff

I put the degree disk onto this and then slid on the thinner ally disk followed by a 2BA washer and nut to secure it in place so I now had my degree disk mounted onto the end of the crankshaft.
I rigged a pointer onto the disk from the lower of the retaining studs for the front cover
and removed both spark plugs.

  Degree disk in place

I made sure pistons were well down the bores, replaced one of the plugs with the stop, put the bike into bottom gear and slowly turned the engine over with the back wheel until I felt the piston touch the stop.


Piston stop in use

A look at the degree disk and I set it to show 40 degrees before TDC (Figure pulled out of the air as a guestimate!) and a note made of the figure.
I then turned the engine slowly backwards until it again touched the stop.
A look at the degree disk showed it reading 26 degrees after TDC so the total distance between the two stop points was 66 degrees.
I adjusted the disk to show 33 degrees, the half way value, and then turned the engine forwards again till it once more touched the stop.
A check of the disk showed 33 degrees again, showing the disk was centred so I removed the piston stop from the cylinder-head. slowly turned the engine forward until I had reached the zero mark on the disk and the engine was at TDC.
I removed the degree disk assembly and sure enough, a look in the cut out showed a clean flywheel, no sign of the marker dot so a quick dab with a magic marker gave me a reference mark for future use. A check of the points showed them firmly closed.
Next was just to extract the advance unit and reset the timing as per book.
A bit involved but it gave me an excuse to play on the lathe and saved the time needed to get a new head gasket up from the LE club.
It was a useful waste of a couple of days and another advantage is I that now have the ability to set the timing at full advance (of 29½ degrees) rather than full retard, a more accurate method but is it necessary for a low performance side-valver?. Surprise here is that Veloce quoted the advance on the LE to the nearest half degree but on the much higher performance singles it’s only given to the nearest degree!.

BMW INDICATORS FAULT (Flash Can Replacement)

Leave a Reply

I’ve had an intermittent fault with the indicators on the BMW sidecar outfit for a while.

Problem with an intermittent is that when you go to fix it, it doesn’t appear or you do something, it disappears and you think you’ve fixed it but next time out it appears again!.

Anyway, this time instead of being slow and dim the both sides indicators stopped working altogether, pointing to a fault in the circuit before the switch, i.e. the flash-can, wiring to the switch or possibly the switch itself.

So after a look at the wiring diagram I saw that if I jumpered two of the can terminals I’d be putting power direct onto the switch, bypassing the can. This meant unplugging the can from its socket and connecting across the two terminals in the socket, 49 and 49a.

Once I’d done this I tried the switch and both sides of the indicators would light, showing that the switch was working ok.

Next suspect was the can and on a closer look I could see some heat distortion of the plastic case and there was a smell of burnt insulation, I popped the case open and it was stinking burnt, well it is about 45 years old so I don’t think I can complain too much.

So on line for a replacement can and find that they are priced at just over £52 each, seems it is an odd-ball unit that’s now obsolete.

Being of Scots blood and hence objecting to such a price I had a look around for an alternative,

I found that the official can had four terminals, power in, earth out, power out to switch and power out to warning light and while these come out as standard 6.3mm spades it does not fit the industry standard relay socket.

A little study turned up an equivalent unit at a price of £7.60 but it would not fit the BMW’s socket, it of course being designed to fit a standard relay socket.

This simply meant that I bought a matching socket to go with the new flash-can.

Before committing myself to wiring alterations I connected the new can with some short leads onto the old socket.

On the flash-cans each terminal is identified and anyway there is a DIN standard for labelling relay connections, terminal 31 is earth, 49 is power in, 49a is power out (in this case to the handlebar switch) and C is to the warning light and as these numbers are marked on the relay it was easy to cross connect.

So next was Ignition on and try the indicators and they are working beautifully so it was just a case now of changing the sockets.

There was a choice of two ways to do this. The new socket came with a set of contacts to be crimped onto wires and then inserted into the socket but I opted to just remove the contacts from the old socket and simply swap them into the new one.

The contacts are held in place in the socket by a locking tab and it is possible to retract this tab by careful use of a jeweller’s screwdriver, a look at the new socket and then at one of the new contacts and how it fits into the socket makes it clear how to do this.

Once a contact was removed from the old socket it was simply pushed into the corresponding place in the new one and then all that was left to do was put the new can into the socket, put it in place inside the headlamp shell and that was that!.

CABLE “BIRDCAGE” TOOL

Leave a Reply

If you refer back to the blog post of 14th August 2013 entitled “Under the Wire” you’ll find a piece on making up control cables.

In this I used a crude method of splaying out the end of the inner wire, basic but it does work.

I was recently shown a special tool for doing this which made a better job of doing this. When I went “on line” to find this tool I discovered that it had a ridiculously high price for what it was, just over £123.

Having had a good look at the tool I knew that I could make one for myself, so I got a length of 8mm by 25mm “bright steel” bar.

I cut two 100mm lengths from this, I put them one on top of the other in the drill vice on my post drill, squared them up and put two 5mm holes through them, on the centre line, one each about 20mm from either end. I then opened out the holes on one piece to 6mm clearance and tapped those in other bar to a 6mm thread.

I could then bolt the two bars tight together, hold them in the bench-vice and draw-file one long face to ensure that both bars were dead level.

I took the bars apart and then re-assembled them with a piece of card, about 0.16thou thick, between them, put them back into the drill press vice. I next put a pop-mark, spot-on the centre divide and in the middle of length of the bars, and then another two, one each about 25mm either side of that.

Next step was to drill a 6.1mm hole, 10mm, deep at each pop-mark.

As there are three different cable sizes to accommodate I then extended these through the bar, one with a 1.5mm drill, one with a 2mm drill and one with a 2.5mm drill.

Now comes the crafty bit, A standard drill has a 118° point so each of these holes now had a shallow conical join where the drill size changed. I wanted a deeper cone here.

You can get what is known as a “spotting drill”. This is intended for marking out work, not for hole drilling, and it has a 90° point so I took a 6mm spotting drill and deepened each hole by about 2mm.

That was the main body of the tool made, I dismantled it and discarded what was left of the card.

I now had to make three punches, one for each size of cable.

I cut three lengths of 6mm round steel bar, each about 5 inches long, fired up the lathe and squared off the ends.

I then used the spotting drill and sunk a 90° socket in the end of each, these were to form the cable end into a double conical “birdcage”.

As the diameter of the relevant cage for each cable diameter was different I now needed to form the punch ends appropriately, a diameter of double that of the cable itself was about right. This meant that to achieve this I would need the open end of the conical punch to be that size and I achieved this by cutting a 90° taper onto the end of each punch until its socket was of the required diameter.

To form a cable end I now have the tool body assembled loose, put the cable end into the appropriate bore and nip up the bolts. Because the bore had been made with the card between the bars the bore is undersize and the cable is firmly held in place.

The appropriate punch is now inserted into the larger top drilling and pushed home. The cable can now be slid further up in its bore until it bottoms in the punch socket and it then further in by its own diameter.

The tool is then bolted tight shut and placed in a bench-vice to hold it and the end of the punch struck with a hammer. This forms the end of the cable into the required “birdcage” which will lock it in place when the nipple is soldered in place.

I could have made this up using angle iron to be easier to hold it in the vice but the only “bright steel” angle I could get was either way too big or if in a convenient size only had a 3mm thickness so I had to use the plain “bright” bar.