Can't get spark on 50 cc Jawa moped

[angloamerican...]

Hi and greeting from Pennsylvania. I recently bought a 1981 Jawa 50 cc moped. I cleaned and took apart the carb. and gastank but don't seem to have a spark. It seems like it isn't a problem with the plug but perhaps before. any ideas? thanks
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rick sowden

[SpannerMonkey]

By any chance is it a jawa babetta?
To the matter at hand, how are the points looking? Are they alright? Too worn?
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My bike? A YX140 powered one-off Monkey Bike, something a little different!

[stinkwheel]

Replace the plug anyway.

As said. I'd check the points for a start off. Give the contact surfaces a light file and reset the gap (worry about the timing after you have a spark).

I'd also check all the spade terminals between the points and the coil. During the 80's the CZ factory seem to have been in the habit of applying some sort of coating to their bikes, presumably because the communist work ethic was to build as many bikes as they could and if there was a surplus, to store them.

This coating was presumably some sort of wax or petrochemical corrosion inhibitor for storage but 30 years down the line, it's hardened into a varnish-like glaze which, importantly in this case, is a very poor electrical conductor. Any 80's jawas I've has have been covered in the stuff.

Another problem is that the connectors aren't very well made and can be pretty loose once they are connected (despite being tight to pull apart).

So you pull the terminal apart, scrape the stuff off the female side with a screwdriver, give the male side a rub with some wet and dry paper then gently pinch the sides of the female connector in with a pair of pliers so they get a good grip of the male side.

If it has a vape type ignition coil (a metal cylinder about 1" in diameter and 4" long with two spade terminals and the HT lead) the best bet is to remove the spade terminals altogether and replace them with ring terminals screwed firmly to the posts of the coil. Loose spade terminals have been the source of many intermittant misfires on my Jawas over the years.

It may also be worth cutting back/replacing the HT lead and either testing or replacing the plug cap. The standard plug caps are extremely poor quality. If you are going to replace them you need to have non-resistor plug caps which are getting difficult to obtain. A lawnmower repair shop is the best bet.
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“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.

[angloamerican...]

Thanks so much for the replies. I don't think it's a babetta but ajawa with some numbers made in 1980. I will check out the points and other tips mentioned. cheers
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rick sowden