Front/ engine sproket fitting question

I remember mine looking similar.  There is however indications from the wear pattern that you could have an issue . Whats important is that the engine and clutch sprockets are in line ,you can check with a thin long straight edge ,  Your local Wickes Diy sell  metal sections.

It cannot sit flush or the nut wouldn't hold the alternator tight against it and hold it in place.

Hello

it may be the woodruff key on the crank is tilted up slightly at the rear not allowing the cog to fit properly in its original position.

you might have just locked the clutch up by fitting the washer inbetween the clutch back plate and the sleeve gear

Barry

Barry is right about the washer ,thats a definate no no.  There may be some bruising of the tapers ,you could try a little valve grinding paste  to bed them together , otherwise find a newer sprocket which may fit better. . I am also thinking you may be able to fit a carefully sized washer inside the spider  at the nut end and it could help neutral selection if there is no clearance at the back of the clutch to the sleeve gear end.

It’s not unknown for an older clutch with a weak spider register to migrate along the gearbox shaft , and causing several issues , sprockets to be out of line and interference between spider and sleeve gear ( which are supposed to move at different speeds ).A tight primary chain  is bad , check again after road test as they are prone to  tighten up after adjustment 

The engine sprockets for some singles look almost the same as those for the Twins. Consequently, if fitted in error, they sit some way off from the cases and the Primary chain run becomes very silly.

The picture that Steven provided looks correct to me. As Dave states......a sprocket that is any further in will leave problems holding it tight on the shaft behind the rotor.  Check out the attached photo of a couple of 650 motors.  magnify to see close-up detail.

Hi Steve,

   Just to add to Phil's post, I think the heavy twins drive-side mainshaft is 1+5/32 inch diameter and the International OHC mainshaft is 1+1/8 inch, so only 1/32 inch difference. Although this is not much, the taper will make it obvious which is the correct fit. Make sure the key is a snug fit, but not tight and tap the sprocket onto the taper with a suitable tube and light hammer to make sure it is seated.

   As Barry and Robert say, do not put a  washer behind the clutch as this effectively locks the gearbox as if in top gear.

I have a 1959 ES2 and found the same issues.  I had to file the new Woodruff key to make it fit.  Once finished it looked exactly like yours.  I tightened up the nut etc. and after multiple test rides everything looks fine. Prior to that I enjoyed a push of around three-quarters of a mile after the previous Woodruff key snapped in place - I had the engine turning superbly but no drive, in fact, I think that it's the best tickover I have managed.  The key had sheared in place half-way up a hill.

Good luck!

The drive should be taken by the taper, the Woodruff key is only there to locate on assembly and prevent cyclic shocks from loosening the taper fit.  There should be a minimal clearance between the key top and the keyway root when all assembled.

Thats usefull information Peter, I did not realise the key clearance was  important. Always something new to learn.