Ign timing not quite as expected...

[drunkmunkey6969]

For the most part, when we set timing on a Lambretta, we see a slight difference in the timing mark when strobed, between tickover and the revs rising. For example, if we are looking to set the timing at 17 degrees......at tickover, the static timing maybe at approx 19 degrees, but as soon as you rev the bike up it sits at its pre-set mark of 17 degrees through out the rest of the rev range (above tickover).

However as i strobed a scoot yesterday, i saw the exact opposite.....at tickover....it was sitting at approx 14 degrees and went up to 17 when revved up......i've just not seen it happen in this 'reverse' order before.

Out of curiosity i tried 3 diferent runs, changing 1 item each time (flywheel, CDI, stator) but all did the same.

Anyone else seen this before and/or got any ideas what may cause it?

[martinr]

have you got the scooter upside down

[wack 63]

Every time I strobe a scoot I see the same.DTI the timing ,set stator then strobe and find the marks advance when revved so I retard the stator so the marks line up when at high revs.I have noticed that even standard Vespas do this as well. I use a Gunson mains powered strobe but have never had any problems on the motors I have done but a mate recons if he uses a resistor cap and resistor plug it does the opposite ie retards.

[drunkmunkey6969]

Thanks Wack....i'll look into that.

Cheers

[eibargum]

Bad earths do strange things when trying to time a bike, always worth checking.

[drunkmunkey6969]

cheers for those responses, i'll have a look at both.

Thanks

[dirtyhandslopez]

Strobe gun on the way out?

[wack 63]

I have had the strobe for @15 + years now but mate has one of those cheap inline ones and his does the same so I think it must be something to do with the ignitions