Need help: Cam shaft + timing chain

[justanother54321]

My bike: 1979 GS850. Lots of work done since it was last in on piece and ran. Rebuilt original Vm26 carbs as per the rebuild tutorial, valves were just redone. Valve clearances are all within spec. New petcock , new plugs wires, dyna coils, dyna s ign.

I just finished putting my bike back together and it won't start. The starter turns the engine but it doesn't sound like anything is happening.

I've checked for fuel and spark, both are present. I've doubled checked the ign timing.

I'm almost positive that my cam shafts are slightly off. Not sure how to do a compression test, but I did hook a comp. test gauge to spark ports and then turned the key for about five seconds. Only got 2lbs of pressure.

So, my question is how do I get the camshaft timing right?

I'm having a hard timing understanding exactly how to count the twenty links that are supposed to be "between" the 2 and 3 on the cam shafts.

Also, are the notches on the cam shafts supposed to line up exactly facing one another?

Any further explanation to cam timing or even better a clear detailed picture would be much appreciated.

Thanks

[Guest]

Hi Just, I'll try to scan the pages in my manual that show how to check valve timing. For the compression check you need to hold the throttle wide open when you are craking the engine over. I'll give the scan a shot in a couple minutes. Ray

[76FJ55]

the cam notches can EITHER line up with the notches facing each other OR facing away from each other. as with all 4 strokes the cams will only turn 180 deg with a full revolution of the crank, so if you line up the "T" mark for 1-4 on the timing plate with the arrow on the crank case the notches should be split half above and half below the split line of the valve cover and head. If the notches are facing toward each other and you crank the engine 360 deg the notches in the cam will be facing away from each other and cive versa.

Next the crank trigger rotor will fit on in two positions. if you have the rotor on backwards you will not get spark at the right time, instead you will get spark at BDC instead of TDC. make sure the magnet lines up with the corresponding pickup. if it does not remove it turn it 180 and re install it.

For compression testing you have the right idea thread the tester into a spark plug hole. make sure you hold the throttle wide open then crank the engine. it usually works best if you have all the plugs out so it cranks faster, and I typically watch the gage and stop when the pressure quits rising.

[justanother54321]

Re: cam setting

Thanks for the info. I've taken a look at the notches and I'm definitey off by a tooth on the intake cam.