explain timing lug on flywheel

[lingeringstin...]

[quote="stinkwheel"][quote="lingeringstink"]

(Do ANY of these linky image things actually work?)[/quote]

[img]https://i.postimg.cc/gJGHkKS0/P1000815.jpg[/img]

[img]https://i.postimg.cc/cLQ3gn8t/P1000816.jpg[/img]


Try like this:

[code][img]https://i.postimg.cc/gJGHkKS0/P1000815.jpg[/img]

[img]https://i.postimg.cc/cLQ3gn8t/P1000816.jpg[/img][/code][/quote]





Ah yes, that seems to work.

[richardeblack]

Hello,
Sorry about jumping on to an old post but am having similar problems understanding this.
I am also confused about this lug on a Yamaha TW125 which I am struggling with.
using a strobe, I see that the cdi sparks just at the beginning of the lug on the flywheel. This places the spark at about 70 degrees advanced and the bike will just about run but very badly and only by keeping the revs up.
Interestingly the approximately correct timing position is just as the end of the lug passes the sensor.
Is this likely to be a problem with the sensor or the CDI?
From reading previous helpful bits it seems to suggest that the voltage is passing the trigger point too soon after the lug starts to pass the sensor.
I have attached a not very good picture which I hope helps to understand my issue. The engine rotates anti clockwise as you look at the picture.
I have tried two CDI units but don't have a spare sensor.
Any advice on how i proceed is greatly welcomed.

[WD Forte]

70 BTDC sounds way too advanced to me.
Normally you get a slightly retarded spark to get a motor running then
as speed picks up maybe an advance of say 30 BTDC on yer common or garden bikes.

With fixed pulsers you'll probably get a one size fits all of say 6-10 ish BTDC
unless it has a 'smart' CDI that can sense rpm and trigger at a lower threshold voltage effectively advancing it.
Sometimes you may get a 'Semi smart' type where the CDI get triggered by a varying voltage from a tps on the carb and it advances the spark
as the throttle is opened.
My 250 Majesty has this.
____________________
bikers smell of wee

[richardeblack]