Colour of spark

[dave81]

I have a SIL GP 150 with 12volt system and cdi unit. I can remember in the 60's when I had series 1 Li 150 with points the spark at the plug was fat and blue. The spark on the GP is small and orange in colour. The scooter runs ok and the spark plug is brown around the electrode and black around the thread. Is this a peculiarity to modern systems due to the electronic side of it.

[Scooterlam]

Good spark should be blue imo.
Check stator as per stickys book and check earths
Do you have an earth from mag housing to frame, if not your spark may just be earthing through your cables.

[MK Monty]

You dont need the earth from the mag housing unless you are after a factory look. the modern stator is earthed on the white direct to the CDI, still you can never have too many earths as long as they are good and not onto painted or powdercoated surfaces

[dave411]

If it aint broke ,dont fix it,

[Tractorman]

I have noticed the spark, from the plug lead to earth, is not as big and blue with a electronic stator as the old points type but as dave411 say 'If it aint broke ,dont fix it'

[Captain Pugwash]

If the spark can jump a 5mm gap at kick speed then you have a good spark, I open up the gap on a spare plug to 5mm hold the side of the plug against the engine and kick looking to see the spark reliably jump the gap on every revolution of the engine just to check if I suspect a weak spark.

[dave411]

Much like Japanese Outboards,very weak spark compared to the American Outboards.Barely visible in daylight,but thats just how they are.

[dave81]

Hi guys
Thanks for all the info on my query. Although It runs ok I will still do the checks mentioned.Happy Scootering!