How to time engine after cylinder head has been off.

Monkey Wrench Cycles · Post by **Monkey Wrench Cycles** » Mon Oct 03, 2011 12:33 pm

I pulled the cylinder head off and did a complete rebuild on it. Its a 64 CB77 and need to know how to time the cams. With the number one piston(left piston while your sitting on the bike, i assume) at TDC where should the cams be? It also has electronic ignition btw if that makes a difference in timing marks.

davomoto · Post by **davomoto** » Mon Oct 03, 2011 2:46 pm

Right cyl on TDC, punch mark on sprocket at 12:00, flats on adv unit parallel with head, and line on points cam at 12:00.

Davo

Monkey Wrench Cycles · Post by **Monkey Wrench Cycles** » Mon Oct 03, 2011 5:20 pm

Now when i get all that lined up and i look at the lobes on the right side cam both are just starting to push the rocker arm up. Not much just a little bit but i would think with it at TDC it would have both rocker arms free at the lowest point at the cam. I checked and double checked and the line on the end of the cam where the points would be(has electronic in it now) is at 12:00, the flat on the cam sprocket is parallel to the head, the dot is at 12:00 and the flywheel is lined up on the T mark. I havent torqued the head down yet as i want to make sure its right first so i dont bend any valves.

davomoto · Post by **davomoto** » Mon Oct 03, 2011 6:51 pm

Yes, that is all correct. You will set the valve clearance with the crank rotated 360 back to TDC. When you set the clearance, rotate it 360 back to TDC, and recheck clearance.

Davo

Monkey Wrench Cycles · Post by **Monkey Wrench Cycles** » Tue Oct 04, 2011 9:30 am

So your saying the point i time the engine at is NOT the point where i adjust the valves? Did you mean rotate it 180(half turn) after its timed to adjust valves? Just trying to make sure we are on the same page as the point where i would time it at would NOT be the lowest point on the cam for the right cylinder(or left for that matter).

davomoto · Post by **davomoto** » Tue Oct 04, 2011 9:45 am

Rotate it one full revolution back to TDC

Monkey Wrench Cycles · Post by **Monkey Wrench Cycles** » Tue Oct 04, 2011 9:57 am

davomoto wrote:Rotate it one full revolution back to TDC

Ok. I gotcha. So that is correct the way the cam is but to set valve clearance i would rotate the engine 360 degrees back to TDC which would put the cam 180 from where its at now.