Turismo 175 ignition timing.

[Bob Purton]

Could someone please help me with the correct proceedure to set up the ingition timing an a 56/Tourismo/ Tresette . I would be most gratefull.

[simonnorthroad]

Is there a Manual on rpw.it for yr bike?

[hendre]

Hi Bob, did the info on the Dutch forum not help you sufficiently?

http://www.motomoriniclub.nl/forum/view ... f=20&t=886

your quote: If anyone else was seaching for the same information about timing its 9 degrees BTDC. Total with auto advance fully open its 40 degrees.

[Arthur Farrow]

I know the timing on my Tresette is 9 degrees BTDC and on full advance 40 degrees but has anybody translated this into distance (ie thou or mm) BTDC ????

Since there is no external flywheel to mark and the crank pinion on the primary side is inaccessible there seems no precise way to get the correct point

Setting the points gap is easy enough
Points cam is not shown in picture it is on the back to the ATD unit
The ATD & points cam is keyed to the crankshaft (via the generator internal rotor)
Points plate rotates about 15 degrees I reckon so there is some adjustment there

Do I really need to fix a timing disc to the ATD find TDC and rotate back because there really is nowhere satisfactory to make a reference mark.

Just be a whole lot easier to say (for example) 5mm before TDC

[Parker3865]

A bit of maths if you know the stroke and conrod length? I think I drew out a graph for my moped.

[morini_tom]

Conrod is 130mm, stroke is 61mm.

I don’t know if there is any pin or crank offset but let’s assume not for now.

The maths gives the following piston distance from tdc at the following timings:

Tresette:
9 degrees BTDC 0.46mm
40 degrees BTDC (full advance) 8.67mm

Tresette sprint:
4 degrees BTDV 0.09mm
42 degrees BTDC (full advance) 9.44mm

Of course, this is piston distance down the bore, so if your plug isn’t on the same axis as the bore then you can’t just set a piston stop to these values… another reason why the flat heads on a Lambertini vee are a helpful feature!

[Parker3865]

Good point about the spark plug angle.
I have an excel file that works it out if wanted? It spits out a graph of angles and piston top depth, just substitute your owns sizes. It is based on maths from the journalist John Robinson's book about tuning 2 strokes.