Hutch’s workshop
Hutch looks at timing your magneto
Hutch checks the timing of his 'new' 1947 Enfield to ease its starting
IHutch
Chelley have a new toy in the shed, a 1947 Model G
The plug and the mag end cap were removed and the engine turned over by hand with the kickstart to establish which way the mag rotated. Then by operating the advance / retard lever it could be easily worked out which way was advance on the lever, the points opening sooner at full advance; in this case full advance was with a ‘tight wire’ at the lever.
A bit of delving into the manual which (fortunately) came with the bike gave some timing data of a 12- 15 thou points gap and full advance at 3/8in BTDC.
Using feelers I measured the points gap at 0.004in, so out with the mag spanners and adjust to 0.012in, always a fiddly job with the mag in situ.
With the bike in gear and while on its rear stand I rotated the engine using the back wheel (the kickstart being inaccessible on the other side of the bike). This allowed me to find the position where the mag points just open at full advance – I use the old fashioned fag paper method for this. I like to mark a point on the rotating part of the mag and a corresponding point on the static mag body using a scriber or thin marker so the timing point can be easily seen.
Now it needs to be checked that the engine / piston is in the correct position for the timing to be right, in this case it was 3/8in BTDC.
For accuracy, engines need to be set up for timing with a timing disc etc, but for a quick check to see if the timing needs further attention I use a lolly stick down the plug hole marked with TDC and 3/8 BTDC – and before anyone points it out I am aware of the sine error etc due to the angle of the plug hole….
So, setting the piston at 3/8 BTDC and the ignition set at full advance I took a look at the timing marks on the mag I made earlier; sadly, as the marks didn’t correspond further work was needed to get the ignition timing set to somewhere near spec.
AN EASY RECTIFICATION.
After reading up a bit more in the manual I removed the timing cover with the intent of pulling the mag pinion and resetting the timing. There are a couple of idler gears driving the mag pinion. I am a firm believer that people don’t set things wrong on purpose, it was also obvious from the gasket that the timing cover had recently been removed. I found that if I turned the mag pinion one tooth on the idler gear next to it then the ignition timing was spot on against my timing marks – happy days. I could only assume one of the idler gears had come away with the timing cover last time it was removed, and to prove the point the bike started first kick when back together – if only it was always that easy.