1952 Peugeot BIMA re-build

[DM]

It looks like there are only 2 wires coming out of the mag, you should be able to see which one is from the points through the apertures in the flywheel. Having worked on cars you should then know which coil terminal the points connect to.

If you can't see it use a meter to check which wire goes to the points (easy unless you have done something strange with the condenser ).

[mini-me]

Its only been going 3 days and its on page two already............................................................................................

[DM]

Don't worry mini, we will aim for a new record just to wind you up 

[Terrotmt1]

Thanks DM.
Found a simple diagram at last and I hope Ican get my DVM probes in through the 2 slots.
I don't think the flywheel as been off ever, so prefer not to remove it.
Mini will always be grumpy! 

[DM]

Why do you want to get the probes in through the slots ?

Measure continuity on the each wire to the mag backplate. one wire will go to the points and condenser so if the points are open there will be a high ohms reading on the meter (turning the mag over assuming the points are clean and making good contact should see the meter alternate from high to low ohms readings), the other wire will go to the generating coil and give a low ohms reading.

[Terrotmt1]

Three steps forward, but no prize today.

Have a spark, not exactly a BIG spark, nothing like the Terrot's, but a stream of sparks when you spin the engine over with the pistol drill (bliss).
Have fuel in the carb, and the plug is only 'just' wet, but fuel on the plug.
Have nice compression...
But, it won't even whisper a fire at all.

Can't help but feel the spark timing is wrong or the spark is too weak in the chamber to fire. Have dosed the attempts with Easy-Start at times but nothing.

There are timing marks on the engine (one) and one on the edge of the flywheel. If you align these marks the access to the points is perfect, so I guess this is where you set the points gap (0.4mm ) as you can set them easy.

However...there is nothing then to set the flywheel to the crank to allow the spark to go at about 3mm BTDC.

Need a bit of help please if anyone can guide me.

[DM]

Well you could read the instructions for checking the timing, which is set by altering the points gap.
It is done this way to ensure that the points open with the flywheel magnets in the correct position relative to the coil stator to get the best possible spark.

http://comet-restorations.uk/gallery/bima_instructions_1956.pdf

I  would have expected the engine to fire even if the timing is slightly out so would suspect you have no spark under compression.

I personaly would throw that can of easy start in the bin, before it damaged an engine.

[Terrotmt1]

Thank you for the link. I had just found the French version though nowhere as detailed under Terrot Lutin, same bike, different name.
That has saved my wife endless hours of fun translating the French...

The EasyStart is the last resort, it did very little on the MT1 but thought it might give some ignition.

The spark on the plug is very weak though consistent with flywheel rotation.
Still not sure if I have the magneto leads on the right coil terminals, somebody before me has re-wired the magneto, orange and white instead of Red and Black.

I suspect the spark will improve if I have the mag re-magnetised?

One good point is on this design, once you loosen the 14mm A/F magneto flywheel nut the nut is captive and acts to pull the flywheel off as you undo it. No puller required.

Thank you again for your help.

[DM]

If you have wires to the coil wired backwards the spark polarity will be wrong but it should still run.

The Magneto Guys show you how to determine spark polarity with a  2 electrode spark gap and a pencil.

https://www.themagnetoguys.co.uk/spark-polarity

Years ago I made a mains powered test box to check flywheel magneto backplates off of the engine.( It will test bare armatures from normal magneto's too).
Basically I wire the ignition as per a car ignition circuit, supply DC power to the coil from the test box and use a NE555 timer pulsing a relay across the open magneto backplate points.
An adjustable spark gap on the test box makes sure I don't run the mag with too big a spark gap and damage anything.

You can get a rough measurement of the HT voltage from the size of the spark gap as it takes 3kV to jump a 1mm gap, again have to make sure the spark gap is not wide enough to cause damage to the coil.

Can leave it sparking on the bench for half an hour to see if the spark deteriorates when the mag coil heats up.

[Terrotmt1]

The spark is about 25% of the. Brightness of the Terrot's current spark intensity.
The Terrot was weak until I had themagnets re magnetised, Villiers Services demonstrated how weak it was before the conditioning...

I gues if the wires are the wrong way round it won't hurt just to get a pop from the engine.
I'll have a look at the link!

[john.k]

I have a Villiers Mk 12 engine on a pump,the spark is so weak,didnt think there was any ......anyway,motor starts and runs no problem,and the pump works 100%,I even pumped hundreds of gallons of oily water out of the fueltank bund at work....the little motor was enveloped in a cloud of smoke ,but kept running till the petrol tank ran dry.

[Terrotmt1]

Reassuring John!
The info I now have off DM will allow me to re-set the engine and I hope it will fire-up.
It would be a good Xmas present...

[Terrotmt1]

Tried several things, but all to no avail.
Checked the timing as per the English Instructions, seems I had it right.
Points 'just' opening when the timing marks are aligned which is 3mm btdc.

Reversed the coil connections to yesterday, no difference, still have a string of sparks when turning the engine over at about 1000 rpm (power drill)
Stripped the carb again, poked through every hole I can find, all clear. Float bowl is full, fuel flows from the tank.

Put some fuel directly into the chamber and tried, nothing, and also then put a slug of fuel into the mouth of the carb, nothing.

The person before me wired a new capacitor in but outside of the mag, it should be inside, but this should be changed (if I had one) just in case..
Need to find out how to check a 6v cap.

Me and French 2 strokes just don't mix well.

[mini-me]

strong sense of deja vu here.

[Rex]

Need to find out how to check a 6v cap.
Me and French 2 strokes just don't mix well.

The surest way is test by substitution and hope the replacement is a good one.
I have an all-singing Fluke meter with a capacitance test function and even that isn't conclusive. Capacitors are funny little buggers.