GS150 Ignition Timing

[Eddie15b]

Ive restored an old VS5 Gs150 and upgraded the elevtrics to 12v using
the varitronic kit that you can now get for these scooters

using the marked positions on the kit ive fitted and strobed it
to find its running at 24 degrees before TDC

originally they ran at 27 degrees before TDC and used 6% two stroke mix

according to stickys lambretta manual the timing should be brought down a few degrees
due to mordern fuels and if im using groundman 2 stroke would 4% be ok as a mix as well

i put in new crank, piston and rings and rebored the barrel so ive yet to run it in

so is running at 24 BTC and a 4% mix advisable ?

or should i go with what mr piaggio advised 50 years ago?

cheers eddie

[Scooterso]

Ive restored an old VS5 Gs150 and upgraded the elevtrics to 12v using
the varitronic kit that you can now get for these scooters

using the marked positions on the kit ive fitted and strobed it
to find its running at 24 degrees before TDC

originally they ran at 27 degrees before TDC and used 6% two stroke mix

according to stickys lambretta manual the timing should be brought down a few degrees
due to mordern fuels and if im using groundman 2 stroke would 4% be ok as a mix as well

i put in new crank, piston and rings and rebored the barrel so ive yet to run it in

so is running at 24 BTC and a 4% mix advisable ?

or should i go with what mr piaggio advised 50 years ago?

cheers eddie

with good quality 2 stroke you could probably run it at 3%.

[soullad]

How many degress does the varitronic retard by?
If you know what pinking sounds like, why not start it off at 24 degrees and keep an ear out as you progress with the running in at different throttle settings. You may find you can actually advance it to the original 27 degrees which would help with starting and tick over etc.

[soosh]

If it retards back to 24 degress then thats fine,ive just put one of these kits on my VS5.Best thing i ever did.I too run mine on groundsman as with all my motors.

[Eddie15b]

thanks for your replys its appreciated

3% is too scary for me as ive still to do 1000 miles in running it in
so ill stick to 4% till thats done as ive spent a lot of time and effort on this scooter
to mess it up on a few % of 2 stroke

the varitronic kit is all a bit vauge to tell the truth so i would have to look into it
and figure out exactly what the retardation is ill come back to you on it

its not pinking in fact i think its four stroking as ive had it out for a run and found
it difficult to rev up initially - but i then stripped it down and found out that the pilot jet was
only a 45 when it should have been a 50

ive sent away for a 50 pilot jet and a new throttle slide and a new needle
so i will report back when i reasemble the carb with the new bits and pieces
and take it from there

cheers eddie

[Mike Holland]

Just a small point. If you decrease the percent oil, then at the same time you are increasing the percent petrol in your mixture. So your engine will be running richer, and might need a slightly smaller main jet.

I rode a GS150 1959 - 1972. Wish I still had it!

Mike