Page 1 of 1

Colour of spark

PostPosted: Sun May 03, 2015 9:33 pm
by 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.

Re: Colour of spark

PostPosted: Sun May 03, 2015 10:22 pm
by 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.

Re: Colour of spark

PostPosted: Mon May 04, 2015 7:38 am
by 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

Re: Colour of spark

PostPosted: Mon May 04, 2015 8:45 am
by dave411
If it aint broke ,dont fix it,

Re: Colour of spark

PostPosted: Mon May 04, 2015 8:51 am
by 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'

Re: Colour of spark

PostPosted: Mon May 04, 2015 8:57 am
by 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.

Re: Colour of spark

PostPosted: Mon May 04, 2015 9:06 am
by dave411
Much like Japanese Outboards,very weak spark compared to the American Outboards.Barely visible in daylight,but thats just how they are.

Re: Colour of spark

PostPosted: Mon May 04, 2015 10:06 am
by dave81
Hi guys
Thanks for all the info on my query. Although It runs ok I will still do the checks mentioned.Happy Scootering!