Help! It won't start.

[Gannet]

My Little Model 40 was chugging along quite nicely on the back of my dinghy when it stopped. It sounded like it had just been switched off. It would not restart.
Back in the workshop it just popped and banged, but wouldn't run.
1. Fuel flowing when the bowl was loosened.
2. Plug sparked when held against head.
3. Points gap still at .020".
4. Compression present.
5. Crankshaft key in one piece.
6. Carb jets clear.
7. Lots of sparking at the points, so as something, indeed anything, needed to be done I fitted a new condenser. Results- no change. Just pops and bangs.
Then I fitted a modern Wipac Mk2 magneto plate off a running (last year) late 60s SJM. Result - no change.
Perhaps the timing is miles out. Felt for TDC and estimated visually the point at which the points just start to open and marked flywheel. Measurement and calculation gave a figure of 51 degrees. This seemed a lot. I thought I had read that 23 degrees was the figure.

What should I do?
Jeremy

[charlesp]

The dimple on the crankcase nose will be correct - it can't have moved. So the timing will be right as there's no adjustment. Yes 23 1/2 degrees is correct, but unless the baseplate is in the wrong position timing isn't your problem.

[Horsley-Anarak]

What should I do?
Jeremy

I would strip it and see what is going on, sounded like a coil problem, but you have tried a Wipac.

I had a similar one where a gudgeon pin clip went down the bore, ruining the piston, and scratching the bore.

I would get your spanners out.

H-A

[Gannet]

Thanks Charles.
Yes, the timing was ok previously and I don't in reality see how it could have changed. Logical thought falls apart as frustration builds up!
The question is; what should I check next?
I like this FV and want to use it on my dinghy.
Jeremy

[Gannet]

H-A,
I have checked the compression, which is about 70 psi. This is with unburnt fuel in the bore. I think my gauge reads a bit high, but does not this figure suggest that the bore and piston are ok?
But, if there is not a better idea, then I will as you suggest 'get the spanners out'.
Thanks
Jeremy

[Michael]

A sudden stop is usually an ignition issue. Have you tried a new sparkplug or at least a different one? How about a different plug lead? Is the plug wet when you try to start it? If not you might have a fuel delivery problem. You say fuel is in bowl, but is it passing through the jets and into the engine? If you use your hand as a choke and give it a couple of pulls, do you have fuel dripping off your hand or is it basically dry? If dry main jet might be clogged

[Gannet]

Thanks Michael,
Yes, I have tried a new plug, another plug lead. Plug gets wet during starting attempts. Checked and cleaned jets.

[phil]

Spark jumping .020" when not under compression is different than it jumping .020" under compression. The spark should jump a 1/4" with a snapping sound and be a blue colour, that should indicate it will do a reasonable job under compression.

[Charles uk]

Your little model 40 is a very different beast to an SJM, & I don't think anyone has done the full research on them as there is not enough interest or a large enough quantity of them to make it worthwile, many of them were not 64cc & virtually none of the parts were interchangable with it's later brothers.
Your SJM should have had a Villiers mk1 ignition.

Perhaps now is the time for someone to strip down an early & late FV & compare all the dimensions with an SJM & list all the differences between them.

I don't know anyone who has tried upgrading the ignition on an FV that I could suggest as a person who's done it, it sounds like your coil is on it's last legs, perhaps you should do the same as everyone else, replace the coil if the resistance is dubious.

This is a fine early Seagull, don't bitsa it, restore it!

[Gannet]

Thank you for your reply. FV1786 I think is quite original, although I had to replace the gearbox (with a correct round hole one). Otherwise it has not been stripped down.
It has, as you suggest, a tired Villiers ignition system. This is on a flangeless magneto plate, the flywheel being dated Dec 1949.
I had used it last year on my dinghy and found it a good starter and very docile.
After it failed a couple of weeks ago, I removed the magneto plate and fitted a new condenser. It still didn't start, so as a temporary measure only, I fitted a complete Wipac to try to start it. It still didn't start, so the problem would appear not to be linked to the original Villiers ignition system.This Wipac came off a somewhat bitsa SJM, which bears a 'W' stamp (so possibly fitted by Seagull later on?). Anyway I am aware SJMs are a very different animal to the FV. Although as I can see with my SJM35, there are many similarities.

I don't want this post to discuss FV or SJMs. I have little experience of repairing Seagulls and I was seeking advice as what I should do to get my FV working again. What do you suggest?
Jeremy

[Charles uk]

Measure the resistance of the coil.

[Gannet]

To recap - I replaced the complete Villiers magneto with a known working Wipac magneto in order to determine whether it was an ignition problem.

With the Wipac, the engine also did not start and produced the same pops and bangs symptoms as previously - ie with the original Villiers magneto.

The original 63 year old Villiers coil is planned to be replaced by a new one. But it cannot be the cause of the problem that I have, as the engine will not start with a known good Wipac system.

Jeremy

[Charles uk]

It's quite possible that the Wipac base plate & flywheel is not compatible with your motor's timing requirements (woodruff key position).

[Gannet]

Charles,
That's something I hadn't considered too deeply.
My thinking, such as it is, was that as the Villiers system is a straight swap with the Wipac system for SJMs and SJPs, then the geometry (in respect of timing) is identical. Plus as the flangeless FV/FVP magneto plate was used on early SJMs (and SPJs?) before being replaced with the 180deg flange plate, then those two are also identical in respect of timing.
But this moves away from the popping and banging symptoms I get when I try to start the old thing, whether on its original Villiers magneto or the Wipac one.
I don't believe the head has been disturbed for 40 odd years. Do you think that I should go down that path and strip the unit down? I really don't want to start getting involved with possible complicated stud/crankcase corrosion problems unless there is no alternative. The engine was fine - until it wasn't if you understand.
Thanks for your help.
Jeremy

[Horsley-Anarak]

I have just had a thought, could it be a simple thing like a crankcase leak?

I had a 40- that stopped because the cylinder had vibrated loose from the crankcase.

H-A