Hit & Miss Engine - Help Needed

G'day all, I have taken more than a few days to build the base for this 6cc Hit & Miss Engine. Really happy how it turned out. I can't get a spark from the plug. Has anyone got any thoughts on what to check out to see why I'm not getting a spark? I've pointed out in the video a few things where I'm stuck.

Check where the wires are soldered to the switch could well be shorting there either to other parts of engine or to themselves

Their ignition moduels are built for Hall sensors that have 3 wires but the contact type switch only required two of those

Edited By JasonB on 25/07/2023 07:17:25

I will do that Jason thanks, I just had a look and they aren't touching but they are really really close.

Appreciate the comment(s) its frustrating when something just can't get even a spark of life to it.

Just saw the governor query, The arm will move once the weights start to get thrown out and engage with the latch on the pushrod which holds the exhaust valve open so it will "miss"

Also worth putting your tester between spark plug body and the wire loop of the earth (not the screw) to make sure you have a clean contact, might want a bit of paint scraping off the head.

How Gov should work

Thanks for the link to the vid Jason, appreciated mate.

You maybe onto something else that I need to check out. I took out one of the head bolts and slipped the earth in the bolt and put it back, But I have only been putting the probe on the head of the bolt and not the wire loop.

When I restore full size engines I always ensure that there a good earth path through the engine parts and castings,I remove any paint from mating surfaces and put spikey shakeproof washers on at least one of the securing bolts/studs to get good contact,, you have an earth attached to the cylinder head,so it could just be paint on the head casting where the earth terminal sits,so clean away any paint and place a shake proof washer between the head casting and the terminal on the earthlead. I would have thought that flicking the contacts with a piece plastic would have produced a spark. Though not applicable to your engine I have come across magneto (low and high tension) ignition engines where some restorers have cleaned off the paint from the magneto seating surface and bracet but had forgotten to clean paint off the mating face on the bracket and the engine crank bed. I would follow Jasons advice with the electrical connections as I have no experience with Hall effect devices.

You may well not see a spark at the contacts as the current is so low, that is why the don't have tungsten disks to resist the errosion of a spark

Faulty ignition module?. I had one of these fail after a few runs.

Faulty ignition module?. I had one of these fail after a few runs.

Appreciate all the replies, thank you all.

For someone like me with limited electronics knowledge is there a way to test using a multimeter if the ignition module is faulty?

Can I put a probe on the spark lead and get a reading?

Easier to put the HT and earth very close together and then make the contacts see here

Can I put a probe on the spark lead and get a reading?

Just hold the lead in one hand and spin the engine. You should be able to tell if there is some output. Better not to hold the engine with the other hand if you have a pacemaker?

That is also a sure way to blow the CDI, they should not be run without a chance of the spark being able to jump from HT to earth

Jason......appreciate that link mate...thank you.

Hit & Miss Engine Help Needed - Part 2

Really appreciate all the help and advice that I have had from - Thank You. I've put this second help video up as I'm still stuck getting a spark and the wiring has me really baffled. I've tried to point out in the video what is confusing me, so I hope I have explained it well enough to be able to obtain some help and advice.....as always super appreciated guys.

Edited By JasonB on 27/07/2023 07:12:07 Moved to the original thread to save people looking for the first.

Edited By JasonB on 27/07/2023 07:12:58

Hi the wireing for a proximity switch is usually brown positive blue negative and black signal. To get an output you need to use the power and signal wires not the negative wire on a microswitch. Have you a wireing diagram for the coil item or some details of model and maker to search with. Try red and white wires on the microswitch 

David

Edited By David George 1 on 27/07/2023 06:26:38

Edited By JasonB on 27/07/2023 07:11:56

With apologies if you have already done so … could you please post a clear photo of the text on that yellow box-of-tricks.

… or a link to the supplier

Thanks

MichaelG.

Edited By JasonB on 27/07/2023 07:11:41

It's the magic in the box.

The black wires be they to the battery, contacts or looped wire to the engine are all ground/earth so you will get continuity.

Unlike traditional points the contacts are not part of the power circuit or the HT circuit they all go back to different parts of the circuit board.

Probably not a good idea to have put +ve power to the red wire with the tester.

I've said it enough times on the three forums all the CDIs I have seen on the market work with either Hall sensor where the middle wire is signal or with some form of contacts where just the outside two wires are used, colour varies between makers. I'll take photos of mine to show the two outer wires of the three being used a bit later

Here is one of my S/S ignitions. You can see that the red signal wire from the CDI stops at the futaba socket and I just have the two outer black & white wires from there that I connect to the contacts on the engine. Same Futaba socket will accept a Hall sensor with it's three wires.

CDI systems work completely differently to the conventional points/condensor systems. Different wiring connections and colour schemes are used by different manufacturers, suggest as it is a new model/machine   you contact the supplier/manufacturer for further help /advice.

Always watch your interesting channel and hope you can get this issue resolved.

Edited By Trevor Johnson 1 on 27/07/2023 08:49:51