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Collection, Preservation and Display of Old Lawn Mowers

Ransomes Minor driving me up the wall

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Afternoon all, 

well ive spent the most part of three days in a freezing cold garage trying to get a minor mk6 going. It has the midget mk2 engine.

ive been through everything, compression, fuel, spark, and everything seems to be there although, it has to be said, the spark is on the weak side. Points emeried and polished etc.

which only leaves timing, I've timed it really carefully, with the notch in the crankshaft at 45 degrees in line with the cylinder at what appears to be tdc. The flywheel has been off but has not slipped out of position on re-assembly

Which all leaves me very puzzled, or is it just down to this very cold weather we're having?

DickBrowne Mon, 04/01/2021

Hi Will

I had a very similar issue with my Bamford stationary engine, although the spark was reasonable, starting was a pig, and got worse as the weather got colder. If I took the spark plug out and gave it a good clean, it was better (but the spark was erratic and not always central onto the electrode). Heating the plug with a lighter would see it start every time. 

The permanent solution was a new spark plug, now it fires up with ease regardless of the weather.

Your issue may well be different, so I offer my experience for what it is worth!

Regards

Richard

Will Mon, 04/01/2021

Thanks Richard - I have put a new plug in it, which I assume is gapped correctly, but maybe I should check!

Will

wristpin Mon, 04/01/2021

It’s quite probable that the problem results from a gradual age related deterioration of the coil and ( if not already renewed) the condenser. Have you taken resistance readings for the coil primary and secondary windings? If the coil is original you will be very lucky indeed if it has not suffered internal corrosion and the only solution is renewal.

Will Mon, 04/01/2021

Thanks for the response Angus, I haven't checked this yet, I will certainly take a look tomorrow. Both coil and condenser are original. I have an electronic ignition module knocking about somewhere, I may fit that to see if it helps. 

Will

DJD Tue, 05/01/2021

Spark at plug needs to be blue, I used to be able to hear the cracking noise before my hearing deteriorated. A red, orange or yellow spark will occasionally start an engine, in the summertime, but you have your work cut out with one of the three main ingredients for an easy starting engine almost missing straight away. At least 50% of starting problems are of spark/timing origin. The capacitor (condenser to the layman, you can't condense electricity!) has the capacity to store energy, there are so many imported rubbish items around these days that buying old stock is a good idea, you can do basic tests with an analogue ohm meter, but not with a modern digital one.

Get a fat blue spark then try again, carb next if no joy, then compression, in that order for me, anyway. On two strokes crank seals are an unavoidable but often overlooked problem area, that give no indication of wear, until you get them out and find they're like pieces of hardwood.

Having said that, older Villiers engines used thick felt instead, for crank oil seals, which is compressed rabbits fur, how they manage to work defies logic!

wristpin Tue, 05/01/2021

I have an electronic ignition module knocking about somewhere, I may fit that to see if it helps. 

I suspect that said module is a solid state trigger such as a Nova or Meco, which just does away with the points and condenser. While it might rectify the effect of a failed condenser it will have no effect on a dodgy coil. 

mikehpw1 Tue, 05/01/2021

Morning 

sorry to jump in on your post but as Wristpin was online thought I'd catch him and my question is about coils so you may need his answer. (-:  when replacing a coil the two wires are unmarked so I assume it doesn't matter which goes to ground on the condenser terminal and which goes the to points terminal? 

Will Tue, 05/01/2021

Thanks very much for the replies all :)

So it sounds like this weak spark is the root cause of my problem. I'm convinced it's timed correctly, after a bit of cranking the plug is wet with fuel, and it's got 55psi of compression which is actually a bit more than another midget I have which runs really well.

Re the electronic ignition yes it's a Meco module (if I can find it!) which I would put on purely to take the condenser/capacitor out of the equation as I don't have a spare condenser handy.

i do have a spare coil but it's also an original villiers so could well be in the same condition.

will report back!

Will

 

wristpin Tue, 05/01/2021

sorry to jump in on your post but as Wristpin was online thought I'd catch him and my question is about coils so you may need his answer. (-:  when replacing a coil the two wires are unmarked so I assume it doesn't matter which goes to ground on the condenser terminal and which goes the to points terminal? 

If an ignition coil has two wires from the coils (not including the HT/plug lead) , one of them is likely to be a common ground / earth for both the coil primary and secondary windings. More often or not that common wire will be grounded to the coil armature or the stator plate. However if it is "floating" it will need to be grounded ; perhaps using an existing fixing. The other wire will be the "live" end of the primary which will go to the points and share a common termination with a wire from the condenser, or it will go to the condenser and then on to the points . Just depends on how the particular manufacturer does it.

 

 

villiers98 Sat, 23/01/2021

Whilst the ignition coil and/or condenser could well be the culprits here, double check  a) the points gap is 15 thou and b) the points separate  when the piston is 5/32 inch BTDC.

Normally I find these engines reliable starters. I flood carb well, full choke and full throttle til it fires . I know the books say 1/3 throttle or similar but never had any luck from cold doing this and have 5 of these engines. Another thing if the plug is wet it needs to be cleaned off well with brake cleaner or swopped for another- this seems critical with some of them. Dare say the electrics are not in best condition on mine but as long as I don't let it stop til warmed up it's fine.

Good luck . It's a really good mower imo.

 

For parts I use Meetens or Villiers Services

Will Mon, 25/01/2021

Thanks @villiers98, I will give it a go as you suggest. It's been so cold since I started this thread that I haven't been able to summon the enthusiasm to get back in the garage!

Yes it's a nice a nice mower, ferociously heavy for a 14", but I think it will give a decent cut, and a good size for my lawn.

hdtrust Mon, 25/01/2021

Hi Angus,I would say is on the right track,but this weather being cold and damp doesn't help,open crank stationary engines certainly don't like this weather.

A little trick we use to do to get a bigger spark across the gap,was to get a pencil (HB) and coat the end with graphite,worth a try.Its the damp that is a killer,-its even started to effect me!