TIMING AN OLD O.S. F.S.60
 

Can anyone help me please? I have dismantled and cleaned an old open rocker OS FS 60 and would like to know how to set up the timing. I can see three dots on the cam gear but no other reference marks. I would appreciate any help.

RE: TIMING AN OLD O.S. F.S.60
 

[b]Boz:

Sorry, it's been several years since I had a rear cam OS apart, but I'll try to help. If I had the bits in hand I'm sure I'd remember, but all is not lost.

Assemble the complete engine less the cam case, leave the head off if it's not already installed. Up to this point you can't get anything out of time. Now the back of the case should show the ring gear, and the cam housing assembled will have the timing gear in front.

Holding the cam housing with the tappet bores on top, when you turn the cam gear you will see first one tappet rise, then the other. Continue turning the gear, you'll see a long interval between one closing and the other opening as you turn it further the second tappet will rise immediately after the first drops. Looking at the gear its normal rotation is counterclockwise anti-clockwise in England, sorry. Anyway, consider one tappet following right on the first, this short interval should be centered at TDC of the piston stroke.

So when you have the cam "Centered" turn the crank shaft to get the piston to TDC, wiggle the crank a bit to be sure it's there, then with the cam positioned stuff it up to the case. Might have to wiggle the crank a bit to engage the gears. Stick a couple screws in the rear housing and double check to be sure that one tappet falls and the other rises as the piston passes through TDC. If it does, you're finished. If not, go back and try again.

Hope this helps.

Bill.

RE: TIMING AN OLD O.S. F.S.60
 

Hi Bill,

Thanks for your help. I'll give it a try tomorrow. I would still like to know what the 3 dots on the ring gear are for. Any suggestions?

RE: TIMING AN OLD O.S. F.S.60
 

[b]Boz:

Two dots on the ring gear and one on the cam gear would be indices for timing, I'd think. Three dots on the ring gear and none on the cam gear? No idea, sorry.

Bill.

RE: TIMING AN OLD O.S. F.S.60
 

The 3 dots are the back side of the screws that hold the ring gear on. There is a dot on the ring gear that is used to time the engine.

RE: TIMING AN OLD O.S. F.S.60
 

Set 1 dot in between 2 dot and you are ready to use your engine.

Jens Eirik

RE: TIMING AN OLD O.S. F.S.60
 

Kimhoff, thanks for your input. I have found a line on the edge of the ring gear that is directly above one of the screw holes. I think this must be the timing mark. Do I now keep this mark at the top and engage cam gear at TDC? I am very new to this so I still need a bit of help.

RE: TIMING AN OLD O.S. F.S.60
 

When you look at the ring gear, you will see the ends of the three bolts that hold it onto the timing assembly. Between two of those bolts will be a small depressed dot. When the piston is at Top Dead Center, that dot goes straight up. You can remove the cover at the rear of the assembly so that you can put a finger on the screw and keep the assembly from turning when you install the assembly into the crankcase.