lambretta electronic timing errors/inconsistency

[sean brady scooters]

this came up today as i was showing dan different flywheels etc............
if looking at the marks on the flywheel window.............the two notches,usually about 2/3mm apart that everyone usually uses to set timing by aligning to white line on pick up.......
i was just pointing out to dan that there is a vast difference between different flywheels and how these external marks line up with the actual magnets internally..........
surely ......there is only ONE specific point at which the magnets trigger the ignition .........
that is........when a certain part of the magnet passes the pick up sensor.........
yet..........strange as it seems .......different flywheels (even from the same maker) can have there notches in different places in relation to the magnets............
what this can mean is ..........that on some engines.......even though you think you have set your timing to say 19.........by the marks...........it could be in fact 21 or 17.............depending on which way your marks are out...........
you could of course be lucky........and it will be spot on............
personally i have never trusted the notches...........and have always used my judgement to compensate around this but i,m sure that many folk just are not aware of such things............
all lambo electronic kits are after all a copy of the vespa set up..........
and so,i have always remade my own notches on lambo flywheels.......following the positioning of vespa ones............
this is a little hard to explain without pics.....but hopefully dan will provide these soon.....................
and also a few more of various lambo flywheels,just to show the amount that these marks can be out...............
has anyone else noticed this........?

[byron]

but what about the position of the arrow on the flywheel...?
I only use the two notches to roughly set the timing statically, they don't come into it when using a timing light.
so I wouldn't be overly concerned if they weren't in the same place, on some flywheels it's really hard to see where they are at all, if any ever existed...
but interested to know differences between distances of magnets and the arrow mark... which always seem a bit vague to me anyway, some just point roughly in the direction of the flywheel circumfrence from several mm away
what we need is difinitive distance around the circumfrence from the magnet trigger point to where the arrow is supposed to point to..

or haven't i thought that through properly...

[drunkmunkey6969]

but what about the position of the arrow on the flywheel...?

The arrow on the flywheel points to TDC and then 17/18/19 degrees etc (or wherever you mark on the mag housing) and then the stator needs to be adjusted so the two lines on the flywheel line up with the two lines on the elec ign pickup.....when the flywheel is in the desired 17/18/19 etc degrees position.

Problem being, the two lines on the flywheel are often nowhere near where they should be on many flywheels....they are quite often out of line with the firing point on the magnets and so should be disregarded in favour of the correct point on the magnets.

[sean brady scooters]

even the positioning/design of the magnets can differ.............on the same make of flywheel

[drunkmunkey6969]

even the positioning/design of the magnets can differ.............on the same make of flywheel

As per the two AF lightened flywheels we were looking at today!

[byron]

The arrow on the flywheel points to TDC and then wherever you mark on the mag housing.

ah yes, I wasn't thinking that part through then...

but, still, does the location of the two marks matter that much ?
as long as the mag housing is marked correctly and the timing is set with a timing light [as it always should be] then the worse that can happen is you'd have to move the stator a bit to take into account the misalignment of the magnet and marks...
in fact that explains why some engines would appear to be out when looking at the marks, but are fine when checked with a light.

[sean brady scooters]

exactly,........and both bought quite recently..............
yet each would give a slightly different timing in reality if set up by the marks.........

[byron]

thinking about it, I guess it doesn't actually matter where on the flywheel the arrow is, as long as it is used to mark TDC and whatever degrees Before as required. so disregard my initial ramblings...

[sean brady scooters]

my point is............
even though TDC may be found as acuratly as poss..........and the relevant number of degrees counted back and marked.............
it can still be out,due to the makers inconsistencys

[firekdp]

The pick up/flywheel marks should only be used as a basic setting to enable the engine to run. As said in an earlier thread http://scooterotica.org/forum/viewtopic ... 9450#p9450all electronic engines need to be strobed to ensure the timing is set correct.