Hello, I had to fit a new coil to my Atco (Villier MK10). Ready to put it back together and time the engine etc. I was reading the below:
on section 7: Re-fitting The Flywheel & Final Set-up it says "Finally, re-set the contact breaker points gap".
Can anyone give move info on this as I am not sure how to set the points gap or what gap I needed to set?
Many thanks all,
Ps the picture below in the old coil
There are two ways of setting the ignition timing , from basics ie measuring the piston position Before Top Dead Centre or the short cut method using the timing marks put on by the factory after having set it from basics.
Using either way the first action is to set the contact breaker point gap. In the case of the Mk10 it is between 12 and 15 thousandths of an inch.
To get really accurate timing only the basic method is good enough , why? Well using the post assembly timing marks one has no idea what the exact points gap was when they stamped in the short cut marks. That said the average owner would probably not notice the difference, plus there is no need to remove the cylinder head. However if the engine doesn’t seem to run quite right, it’s off with the head and do it properly!
Adjusting. Replace the flywheel and do the nut up just finger tight . Turn it until the points are wide open . This should align one of the windows in the flywheel with the points. Check the gap with a clean feeler gauge. If it is in the 12 - 15 thou range , leave them alone but repeat the paper cleaning routine.
If they need adjustment, release the big slot head screw a quarter of a turn and make the adjustment. Tighten the screw and repeat the paper cleaning routine.
If I had the ignition system as far apart as is needed to change the coil I would take the points out of their housing and check and clean each point face ; if necessary using a slip stone to remove any peaks or pits. Then of course, there’s the condenser tucked away under the points box. If it’s as old as the original coil, it could be well past it’s best.
Thanks wristpin for your comments.
I cannot see factory marks on my fly wheel. There appears to be some odd drill marks around the outer edge plus a screw near the centre nut I cannot see any stamps etc.
I need to go and buy a feeler gauge before I go any further.
Lastly - what is the paper cleaning routine you refer to?
Take a strip of clean copy paper , 90 gsm or heavier . Turn the flywheel so that the points close on it and slowly pull it towards you , but before it comes out use a small screwdriver to hold the points apart to release it . The reason for releasing it is that if you pull it right out the points may pinch the end and trap fibres between them, undoing all the cleaning etc.
when buying a set of feeler gauges, get a set with a removable screw hinge so that you can take out the one that you need ( 13/14 thou ?) . A lot easier to use than having the whole pack swinging about. Also if the gauges have wide rounded ends it makes life easier if you taper the ends of the most used - not to a point but to about half the width of most common off the shelf gauges.
Someone will know, but I suspect that the drillings are to make sure that the flywheel is balanced - I believe there's some weird physics about rotating objects where any imbalance will be at its worst at about 1000rpm (certainly this is true for the centrifuges at work), which is probably just the sort of speed your engine will run at.
I cannot find timing marks on the flywheel therefore I need to remove the head !!. I am hoping it is not too hard. Please can you give me a little advise how to find BTDC? Also cleaning the old carbon deposits? WD40 or Carb cleaner - are either okay to use? I don't currently have the Villiers manual with me to find the setting BTDC - I was reading the manual at work and left it there before lockdown.
I am using your comments above and below to set the timing etc:
TDC . If possible you need to read up on it a bit. Basically there are three methods - by eye and feel , using a dial indicator or the most accurate of all , the positive stop method using a piston stop and a timing disc. For your purposes, with a bit of practice, the eye and feel method is probably sufficient. Yes, the head has to come off but although none of it is "rocket science" I really wonder whether you should be venturing this far alone. Do you not know someone who may have run a motor bike of such like and is a bit small engine savvy and could give you some hands on guidance?
Scraping off carbon etc. A combination of carb cleaner and a hard plastic or wood scraper is the safe way . Gouging with an old screwdriver is not recommended for alloy components!
Thanks for the info as always. I fitted a new coil and now have a really nice spark. I found the timing stamp now on the fly wheel but I need to find TDC of the piston before I tighten the fly wheel again. I will try it with the eye and feel method to start with. I will read up more on the topic but sadly I don't know any one in my local area, that I know of, that is engine savvy. That said there must be a few as I live in South Northamptonshire nr Silvestone.
This was really straight forward in the end. removed the head, the bore was nice and clean, cleaned valves and head to ensure old carbon is removed. Easy to find TDC especially at TDC on the stroke after compression as the flywheel rocks between the point when both valves are just closed. timed the points at TDC to 15 thou. Points just started to open when piston was at 3/16th " BTDC (approx 20 degrees before timing marks line up). Put it all back together and runs really well with my nice new coil.