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Collection, Preservation and Display of Old Lawn Mowers

Ransomes Auto Certes - No Spark

Hi all, I have a Ransomes Auto Certes (Mk 8?) I'm trying to get running. Compression is good. The carb and fuel system might need a bit of a clean But that's not what worries me. I put some petrol directly into the carb, pulled the recoil and it still wouldn't fire. The plug was wet so it was getting into the cylinder. I changed the plug but no joy. I held he HT lead just away from the tip of the plug while pulling on the rope and there was no spark.

I took off the cowl and the little inspection plate on the flywheel. It has a points system like the one in the picture below. The problem seems to be the arm the points are on is very stiff. I have to use a screwdriver to prise them apart and when I do they stay stuck open, rather than springing back shut. The little leaf spring on the arm looks intact. I've tried spraying WD40 on it and working itback and forth but it's still tight. Could this be my problem?

Something else that I found was that there is nothing attached to the back of the On/Off switch. I assume there should be a wire of some sort? Could you tell me where this connects to, as I'd like to return it to original spec. I know the mower ran like this but that was over 20 years ago. Thanks

wristpin Mon, 05/10/2020

Quite possible that the pivot pin of the moving point has rusted .  Carefully remove the push retainer and work the moving point back and forth while pulling it outward enough to be able to clean the pin.

Condensers do fail or weaken with age so it may be a good time for a new one.

The switch. One terminal will have a  connection to earth soldered from one terminal and then squeezed between the switch and the cowling. The other terminal should have a wire routed out to a connector just below the fuel tap. The other half of the connector has a wire that shares the HT lead grommet into the magneto and usually shares the junction of the coil primary wire, and  condenser wire  where they join the points.

While you’ are in there, give the points a proper clean .

redgiant Wed, 07/10/2020

Thanks for the reply wristpin. Are there supposed to be two terminals on the On/Off switch? There appears to be only one on mine, or am I mistaken? I am going to remove the flywheel as I don't have enough room through the inspection cover. Am I right in thinking the three holes on the flywheel are 7/16 UNC? I will try to make a puller like I saw in another post but am having difficulty sourcing the right bolts/ threaded bar.

In the meantime I removed and cleaned the carburettor. I discovered a small bolt and lock nut are missing from the body where the throttle cable enters. I'm pretty sure this is 4BA and have ordered one off ebay.

Thanks again for your help, I shall respond soon, hopefully with a first start in about 25 years!

wristpin Wed, 07/10/2020

Switch. I think that the "empty" rivet would have had a terminal . A side on view might explain. Does the terminal in your image have a wire soldered to it and folded down under the switch to be clamped between it and the cowling

Puller screws - 1/4" UNC . Screws and studding on ebay or from Namrick fasteners - and others! This one is well made and will last for ever! Not me!!…

Carb screw is the idle stop and just holds the slide a bit off shut . Fairly certain that it id BA but I've never had to buy one.

redgiant Sun, 11/10/2020

As for the switch you were dead right - soldered joint on one side, the other completely broken off! Can these style switches still be bought?

wristpin Sun, 11/10/2020

 Can these style switches still be bought?

Don't know, but I suspect that Ransomes may have commissioned batches made to their spec from one of the proprietary switch suppliers.  Not difficult to modify a stock switch from the likes of RS Components . Go for a switch with a metal shafted toggle ( even if the end bit is plastic) as being next to the recoil it’s quit vulnerable to knocks.