gs newb. need help timing cams

[Guest]

hi everybody. i'm new to the forum and new to working on these on old gs bikes. I picked up a 1980 gs750e the other day for $400. It had a bad head gasket and leaked oil horribly. It drove good and was is in very good shape cosmetically and mechanically, so i figured it was worth buying. I have the head off and I am waiting on the new gaskets to get here. How do i time the cams when i put it all back together. I have a good visual memory of how they went but I just want to be sure i don't get it a tooth off and hurt the motor when i start it again. Any help or suggestions would be greatly appreciated.

[Nessism]

Info is in the factory service manual. You can download one for free here...http://members.dslextreme.com/users/bikecliff/

[Steve]

Yep, definitely need a manual to refer to, but the basic procedure is to align TDC on the crank, install the exhaust cam so the #1 mark lines up with the front of the head. Count the proper number of pins that are supposed to be between the #2 mark on the exhaust cam and the #3 mark on the intake cam, install the tensioner. Of course, there are missing steps here, like "tighten the cam caps (to the proper torque)", those should be obvious, but are spelled out in the manual.

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[p_trice]

thanks for the advice

[p_trice]

I have read the manual and looked at the cams and timing marks. the manual says to line up the timing mark on the crank shaft for tdc. But there are 2 tdc marks. one mark is for piston 1 and 4 at tdc, the other mark is for piston 2 and 3 at tdc. which timing mark do i use? In my past experience working on motorcycles, i usually line up the 1 and 4 tdc mark.

[Nessism]

You need to align the 1-4 T mark

1-- mark on exhaust cam sprocket pointing at the gasket surface

As you are installing the intake cam count the pins between the 2 on exhaust cam sprocket and 3 on the intake cam sprocket. The service manual will indicate how many pins are required.

Wind up the cam chain tensioner and set the set screw. Install the tensioner and release the set screw - you should hear the plunger spring out and the slack should come out of the chain. Back off the set screw 1/2 turn further and reset the lock nut so it doesn't fall off.

Be careful to turn the engine over by hand a couple of times to verify the marks are where they are supposed to be before you hit the electric starter. If the timing is off, and you hit the starter, you will bend valves.