TS 250 4 speed ran lovely then stopped

[Nedtwolegs]

Hello
I am a new owner of a 1974 TS250 4 speed. I was enjoying ridding it yesterday. Was running well for over an hour. Then got on a dual carriage way up to 60mph and bike cut out. Changed down and just before slowing down to a stop it fired up and off I went again. For a bit. Then it cut out again.
Could not get it started.
Still can't.
There is a spark. Plug was greyish. Battery fine.
Fuel coming out of fuel tap.
Any suggestions please?
This is my first two stroke again since 1980s.

Rob (Liverpool)

[den]

faulty spark plug,,probably a cracked ceramic insulator,,( bit down the middle).when the plug get very hot,the crack expands and the spark is lost up inside the plug, trial and error,, cheapest first,,check the plug cap too,,

[Nedtwolegs]

Thanks Dan.
Swapped over spark plugs but no joy.
Started a bit of investigation today.
First time taking things apart.
Some oil behind the plate on clutch side of engine held on with three screws.
Bike does not seem to have as much compression. Though I am rarely new to it.
Kicked over loads of times and then checked plug. Seemed rather dry not oiled up.
Float bowl was filled with clean petrol. No bits.

[HENRY]

My ETZ125 does this occasionally and it is a worn fuse that has become loose in the fuseholder. Vibration from bumpy roads don't help.

[Blurredman]

Grey sparkie? Any two stroke shoold have a nice brown colour to it.


I've happened to have this more than once on a fast test run or just a motorway acceleration and sustain. Never did find out what it was.

It could be loose electrics, my fear was a heat seize (but then the rear wheel would have locked). Look at the points, make sure they are both gapped corrected and timed correctly.

[DAVID THOMPSON]

i have had a lot of poor quality fuses showing up both in auto spares and radio parts

i like to check them with a light bulb

but watch the light bulb wattage a 100 watt headlamp bulb is not what you want

a 194 is a good one to use

dave

[Nedtwolegs]

Engine rebuild by Moll Springs. Running lovely now.

[DAVID THOMPSON]

i was thinking maybe the high speed run took out the rings or holed a piston..

setting in storage for long periods results in the rings loosing there tension and the points spring if compressed
also goes make them not close at higher rpm
it runs but very poor