Motorbike not sparking but will once regulator rectifier feed is connected to earth

curly head · Nov 8, 2018

Please can someone advise or help in anyway before I go completely insane
I have a ktm project bike that doesn’t spark unless I disconnect the voltage regulator rectifier and run the constant feed connection (reg rec side of loom) to earth.
I spoke to so many specialists who cant resolve and I cant understand it either.
The reg rec has a good earth when I tested it too.
Anyone he this before or recommend a bike guru?

TJ Anderson · Nov 8, 2018

No lights so not an EXC then.....Is it an SX you have?

You may have an issue with reg/rect. 1st though, check the stator windings with multimeter (set to ohms)

Should have

Black/Red to Red/White= 25 ohms

Red to green= 100 ohms

PEG · Nov 9, 2018

Hi,have you checked where the CDI gets it ground from?

It is possible the CDI is using whatever lead you are grounding,to get it's reference from,if it's own ground is missing. I wouldn't be grounding out wires willy-nilly,as you could goose an expensive component.
Got one which keeps needing a map reset,issues starting and running when hot...lots of fun,but not as reliable as me old Maico

TJ Anderson · Nov 9, 2018

I'm too young for Maico's but love 2T's. Collectors items now. 490's looked like they were pretty brutal back in the day! The new KTM/Husky 250/300 TPI's look pretty sweet and might be the saviour of the 2T.

curly head · Nov 10, 2018

Thanks for your replies, it is a sxf motorcross bike
i checked everything again and stator resistances are good and have 12v going to the reg / rec
Have ordered a new reg / rec so fingers crossed this cures it!
I can’t see how a reg / rec would stop a spark - Never had these problems before with ktm’s