Rotor question

What are these marks on the back of the rotor? And is there any danger concerning the strange marks on the front of the rotor? Looks all wrinkled.





Tommy

Just a wild guess, maybe for static timing a triple?

fiatfan said:

What are these marks on the back of the rotor? And is there any danger concerning the strange marks on the front of the rotor? Looks all wrinkled.

Click to expand...

Yes, they're the two sets of (not necessarily static as the marks are also used for strobe timing) 38 degree BTDC marks for early ('A') and late ('B') BSA and Triumph triples.
I doubt the "wrinkles" are anything to worry about.

L.A.B. said:

fiatfan said:

What are these marks on the back of the rotor? And is there any danger concerning the strange marks on the front of the rotor? Looks all wrinkled.

Click to expand...

Yes, they're the two sets of (not necessarily static as the marks are also used for strobe timing) 38 degree BTDC marks for early ('A') and late ('B') BSA and Triumph triples.
I doubt the "wrinkles" are anything to worry about.

Click to expand...

Aaah, interesting, thanks!
Tommy

Hi.

But the rotor of the triples is not larger than that of Commando?

Ciao
Piero

pierodn said:

But the rotor of the triples is not larger than that of Commando?

Click to expand...

Early BSA/Triumph triples had an RM20 alternator, the rotor and stator are slightly wider than the RM21.
Later T150 models had an RM20 rotor but had an RM21 stator.

The T160 had the RM21 stator and narrower RM21 width rotor.
Lucas eventually stopped manufacturing the RM20 width rotor and the RM21 type is the one currently available as a newly manufactured part (from Lucas, Sparx, Wassell etc.,) and why it also has the triple cylinder timing marks on the opposite end.
A spacer (71-4435) and alternative rotor fixing nut (21-2182) can be used when fitting the narrower rotor-if required.