US model appears to be a 3 speed by the parts diagram.  Other countries may have had a 4 speed?

Diagram shows gears 1, 2, and 3 on the input shaft.  The double gear at the end of the input shaft is used to provide the "low range" reduction when low range is selected.  It just freewheels on the input shaft.

 

So how this works is drive sprocket is bolted to gear 19 in diagram below.. Gear 19 is one of the "ball lock" gears.  When selector is in "high", ball lock pin is pushed out by springs and locks 19 to output shaft.  Gear 18 (the other ball lock gear) and double gear in the previous diagram just freewheel.

 

When selector is in "low", it pushes the ball lock pin inwards which releases gear 19 from the output shaft and locks gear 18 to the output shaft.  Gear 18 and 19 mesh with the double gear on the input shaft so now the power goes from 18 to the double gear on the input shaft to gear 19 which drives the sprocket.  That "detour" through the double gear on the input shaft gives the added reduction of low range.

 

Ah, yes, of course Mark, wrong again lol, i'm getting used to this. What's more it looks like i might've been talking rubbish back here in this page i found just googling. Back to school for me. Maybe the YL2CA i had 'that long' ago was 4 speed & no high low.
yamaha-enduros.com/index.php/forum/fng-i...0-yamaha-trailmaster

I didn't say you were wrong at all...  other markets had different offerings.  I'm pretty sure there was a 4 speed with hi-lo range.  Might have been a Honda though.

I know some of the little Yamaha's came with different transmission options in Europe (for example) that we didn't get here.

I was just working through how it operates based on the parts diagrams. 

Haha yeah but--i think i'm wrong, coz can't find it on partzilla. Wish i'd taken pics of the one i had. L2CA that is. Happy days.