Thread: 81 ct70 backfire, stuck after camchain adj.

Trying to get an 81 CT70 back to life. Finally got it to start and run for a couple seconds, the will backfire and die.

New, adjusted points and condenser. Adjusted valves.

Opened the cam chain cover and the "O" was off about 2 inches from the "V" when flywheel was on T. (V is at 9 o'clock O was at 11 o'clock before adj)

Popped off the sprocket and aligned the O and V when on T.

Now the bike will kick once "have only tried by hand) and the engine seizes. i can rotate the flywheel clockwise a bout 2 turns before meeting some resistance. I can rotate the flywheel about the same counterclockwise and it meets resistance again. I have the plug out. It spun freely before aligning the marks.

Any thoughts or help would be greatly appreciated.

Thanks

O mark should be facing foreward towards the cylinder head. You should be able to draw a sraight line between the key on the crankshaft and the O mark on the cam sprocket. Click on Webboard. Then go to resources and links section. Click on online shop manual. Then click on section 20. This will give you a better understanding of what I am talking about.

Kind of hard to see the pic on my computer but looks like the key is at the 9:00 position and the O is at the 9:00 position.


Does that sound right?

Thanks

May have another issue. This is a picture of the shaft the flywheel slips onto. It looks like the key is flush with the shaft.

1. does this need to be replaced?

2. Is this the key that should be in the 9:00 position to set the cam chain position?

Thanks for the help.

That key doesnt look like its got much in the flywheel,I would replace it so you dont have problems.I try to keep a couple spares cause of that

Yes the key is at the 9:00 position along with the O mark. Make sure the key is on the side of the crankshaft that is facing the cylinder head.

Does anyone know if the Woodruff key for the crank is available as a standard size in a hardware store like True Value, Ace etc.

Seems like an odd size and was hoping someone had success at a local store.

Thanks

Yep, your key sheered off and threw your electrical timing off. That was your original problem. Your cam timing is off now. Make sure to get your mechanical cam timing back in order before you try to spin it over. The resistance you felt was the piston hitting open valves. I hope you didn't try to force it to spin over because you can bend a valve when you do that. You might be able to find a woodruf key at a hardware store, but I think I'd either order one or get one from a honda dealer.

try a local lawnmower shop i get my keys and stuff off of an older gentleman who runs a snapper repair shop. its likely other engines would use similar keys