Flywheel key question

[Ocean1]

I held back from saying why , I couldn't see any evidence on the shaft,( Hetzian? but wasn't sure) We are talking a motorcycle ( possibly inline 4 ) those fluctuations ain't as big as me Enfields flywheel. .you working for Rolls Royce??

Stephen

Why what? Go to all that trouble?

It's true most of my experience has been on big singles. But faced with slightly damaged keyways that process has worked well for me, quicker fixes have cost me time and money.

Truth be known if it was mine I probably couldn't stop myself recutting the keyways.

[Brian d marge]

Why what? Go to all that trouble?

It's true most of my experience has been on big singles. But faced with slightly damaged keyways that process has worked well for me, quicker fixes have cost me time and money.

Truth be known if it was mine I probably couldn't stop myself recutting the keyways.

hahahaha I thought your reply smacked of large flywheels ! I was thinking , how much wieght has he got on there!!

I had a rummage through the scrap bin and I found , 2 Cr250 cranks , one I had apart, one Enfield crank and another complete cr and the different construction methods .. interesting ,,,, quite a well thought out ??? crank for the Honda , very cheap to make .....

I know its off topic but I might post a photo ,,,,the Cr fly wheel ( alternator ) from memory 6, 800 grams ,,the enfield ......not much more ....

Anyway I digress


back to arguing about key steel ..... 600Mpa key on a 300 Mpa crank............

Stephen

[Ocean1]

I had a rummage through the scrap bin and I found , 2 Cr250 cranks , one I had apart, one Enfield crank and another complete cr and the different construction methods .. interesting ,,,, quite a well thought out ??? crank for the Honda , very cheap to make .....

It's been decades since I was inside a CR250.

But it's a Honda, the design will be well thought out.

[Brian d marge]

It's been decades since I was inside a CR250.

But it's a Honda, the design will be well thought out.

Iknow its off topic a little but I here are the photos ... havent times changed .....

ok as you were ......

Stephen http://www.kiwibiker.co.nz/forums/im...isc/pencil.png

[imdying]

As someone said, lap the flywheel onto the shaft until you get 95% contact shown by bearing blue on a light push / light 20 degree twist.

Place the old key into the keyway and lay a 5thou plastiguage along it's length. Place and torque the flywheel up. Remove it and check the clearance. Now that you know what the radial clearance is chuck the key away. Get a fresh bit of 4mm keysteel, (yes, there's a standard, and a reason for it) and find someone with a surface grinder.

Cut a piece of keysteel at least 100mm long, (less and the mag chuck won't hold it) and grind the piece to 3.2mm. Use that as a feeler gauge in both the shaft and the flywheel, grind a thou at a time until you can feel it drags hard on the width of the keyways without being so tight it won't seat right down.

Grind the key to the exact radial dimension you've already measured above. Cut it to length and carefully chamfer the corners, 'prox 0.2mm. Trim the key to length and radius the ends as/if required.

Right, I'll do that then, cranks too good to waste.

[imdying]

I should mention that the manufacturer came back to me and said yes a 3x3 key is what I need. I went to South Island Bearings here in Chch and they gave me a couple to try FOC, very nice of them. I tried that, and it appears to be a perfect fit, but I've plenty of spare time so some careful measuring and a lap it is.