LAsh numbers for Dummies.

[Freakshow]

OK im not the smartest bloke and i have read this is few times in the manuals but im not sure what it all means in laymans term.  Can some one explain this simply for me. 

On the Primary drive cog, on the YAmaha, it has a lash number engraved near the teeth, now so does the clutch basket from memory, now i alway put back the same ones i took out, but on the weekend i had 2 motors apart side by side and when i went to put them back together i found i wasnt so sure i was holding the right one in the right hand.

Now they both had differant numbers and i do remeber the numbers dont matter so long as when you add it to the other number on the other cog they equal between xyz and xyz.  Not that i can remember what that inumber is right now, but can someone explain what the lash numbers are trying to tell me ? is it the hieght of the cog, the angle or the width AND AFTER 35 YRS if the parts are worn anyway does it matter as the clearance would have grown out by now anyway

So
1.  what does the lash number really mean.
2. what is the effect if it doesnt add up to the magic number.
3. effect if the primary gear is changed/basket change if only one is new ?? etc etc

[Lozza]

Ummmm.............................. a pic might help.

[matcho mick]

freaky,it's going to be the primary backlash value,( between the pinion,& clutch gears),which you already realise ,just try the combinations ?,get some thickness guage tape from bearing shop,see which combo has the smaller clearances,or just split the value differences?,or get a magnifying glass and look at the teeth mesh patterns,they should/must be different as to obtain a match,(say one motors box ran dirty oil,it would show up as  greyish colour on the teeth),hth's
ps enie meeni minee ^****

[Freakshow]

So the short answer is there isnt an answer, your all  banging around in the dark like me :O)

lozza a pic wont help you.  You either know what they mean by this or dont.