Jawa x30, very weak spark

Hi there! Recently got this 1981 jawa x30 (207? 210? Something) for pretty cheap.

Freed up the motor and discovered that it has pretty weak spark (you can see it but its razor thin, and you have to spin up the motor pretty fast to get anything)

And knowing jawas, it has a very complicated ignition, and im not sure where to start, changed the plug, same thing. Guessing it's the coil or the thryster. As the alternator works for the headlights (this is the one with the black 4 wire box and the silver cylinder coil)

Any input on where to get parts as well? Only thing on treatland is tires.

Thanks again!

20200621_142103.jpg

Re: Jawa x30, very weak spark

Heres a better picture of the ignition system, the coils do have surface rust on them, but the headlight works just fine, so im ruling out the alternator as the main problem (edited)

20200621_181822.jpg

Re: Jawa x30, very weak spark

Pushrod Fifty /

I would start by cleaning every electrical connection and making sure they make firm contact, clean that rusty mess with electrical contact spray. Replace the plug wire and cap.

Re: Jawa x30, very weak spark

Well, also, i tested the thyistor and the coil today.

160ohms for the thystier between the 1 and l

And 1 ohm for the coil, seems to be within spec

Guessing its going to be a bad connection somewhere

Re: Jawa x30, very weak spark

It's always the thyristor. Trust me, build one or buy one. Just do it.

Re: Jawa x30, very weak spark

im hoping to build one in the future, but i replaced the coil wire and cleaned the grounds back up, were back in business!!

clean spark, now to address the second issue, 45psi of compression....

Re: Jawa x30, very weak spark

The capacitor component of the thyristors like most don't age well. If it works, my experience has been you get a miss at speed. Hopefully your low compression is simply stuck rings. Good luck, make it go!

Re: Jawa x30, very weak spark

thank you

im hoping to get it running and just to ride around for fun.

im guessing the rings haven't moved in 10 or so years!

woundering if the compression release has had it

Re: Jawa x30, very weak spark

Guess you'll find that out when you pull the top end .

Then , lap the decompression valve into the seat , so it won't be a problem .

Re: Jawa x30, very weak spark

this page has some details on testing the thyristor:

https://www.mopedarmy.com/forums/read.php?6,1834014,1834512,flat=1#msg-1834512

and a great verview PDF here: http://www.jawamoped.com/JawaMoped_Electrics_-_ignition.pdf - if nothing else read this one.

and common issues here: https://www.mopedarmy.com/wiki/Jawa_ignition_testing

the DIY instructions to build one are here:

https://www.mopedarmy.com/wiki/Jawa_Thyristor

I have done that twice and it goes from a weak little zap to fucking inch long lightning bolts.

Glad it works but theyre notoriously problematic and I still support Franks suggestion of replacing it when you can. Do read that PDF if nothing else.

Re: Jawa x30, very weak spark

> Born to be WillD Wrote:

> -------------------------------------------------------

> this page has some details on testing the thyristor:

>

> https://www.mopedarmy.com/forums/read.php?6,1834014,1834512,flat=1#msg-1834512

>

> and a great verview PDF here:

> http://www.jawamoped.com/JawaMoped_Electrics_-_ignition.pdf - if nothing

> else read this one.

>

> and common issues here:

> https://www.mopedarmy.com/wiki/Jawa_ignition_testing

>

> the DIY instructions to build one are here:

>

> https://www.mopedarmy.com/wiki/Jawa_Thyristor

>

> I have done that twice and it goes from a weak little zap to fucking

> inch long lightning bolts.

>

> Glad it works but theyre notoriously problematic and I still support

> Franks suggestion of replacing it when you can. Do read that PDF if

> nothing else.

yup, anyone know the specs on what thyristor to get? as i clicked the link but nothing, as id like to know before the original box kicks the dust.

and the bottom ring had a hairline crack and broke in my hands, ordered new rings off treatland, hopefully it should run!

Re: Jawa x30, very weak spark

hone that cylinder when you put new rings in

check the end gap

wire wheel that rusty ignition rotor too.

its a 207 engine.

reliable as a stone except for the ignition

buy an extra thyrister as a spare

red-yellow-white-blue.....wire sequence

i had a maroon 207 and ran it hard all summer long

it would only go 29mph but i loved it

Combloc styling

Re: Jawa x30, very weak spark

Just like Kyle #1

IM BAACK!

So, got the rings in and it puttered puttered ran then died (assuming the thysistor box last hurah!)

Now.

I would like to build the diy one, can someone link me the 3 pin thysistor they used in the picture? As the link isnt leading to anything and im not familiar with thysistors.

« Go to Topics — end of thread

Want to post in this forum? We'd love to have you join the discussion, but first:

Login or Create Account