Engine timing

[Guest]

I took my head of and put a new gasket on and i can tell my timing is off, valve clearance is set correctly and i can feel air coming back out of the intake side.

1. take slack out of chain and align 1 on ex cam to head
2. 2 arrow up count 20 links
3. is the chain tight???? and attach to 20 on intake

4??????

the service manual is pretty vauge could use some help.
engine pic.jpg
currently pushing around 30 psi on all cylinders

[Nessism]

Are you aligning the crank to 1-4 T before installing the cams?

[paulie2026]

i have a aftermarket dyna igition it says tdc and i can see cylinder 1 at the top.

[chuck hahn]

So take a screw driver in the plug hole and slowly rotate the crank as you FEEL the piston come to TDC..then take a looksee at where the dyna says its at. You can trust the feeling the piston come to TDC and then check the cams again. If the arrows and pins are correct install the cam chain tensioner. roll the engine over 3 or 4 full revolutions and watch as all the cylinders valves operate and see that they do not stop you from rotating the crank. If it stops DO NOT force it. Find out hats out of time. If its all good then button it up. Then readjust the TDC mark on the Dyna would be checking process.

[paulie2026]

does the arrow on the intake camshaft have to be straight up and down? its 20 pins away from the exhaust but its not straight up and down

[chuck hahn]

yes..1 is flat with the front of the head surface and 2 will be straight up. 3 is straight up with 20 pins between the 2 and 3 arrows. Sounds to me like the intake cam isnt indexed right.

[chuck hahn]

What bike and year..maybe edit your signature to include that tidbit of information.

[paulie2026]

its a 78 gs750, im confused if i put the cam chain idler on iot will pull the cams together

[chuck hahn]

Heres the service manual.

http://zeus.mtsac.edu/~cliff/storage/gs/GS750_Service_Manual_early8valve.pdf

See page 55

[chuck hahn]

Actually start on page 52.

[paulie2026]

im following that service manual its 20 pins off but if i put the cam chain idler on the sprocket moves.....

[chuck hahn]

It will move..long as the arrows are right and the count is right...along with the T mark on the timing plate is all you must be certain of. Insert the cams like they should be..verify the pins..put on the idler..install the tensioner. Rotate the crank with the 19 MM wrench and watch that all 4 cylinders intake and exhaust valves open and close without anything jamming as you turn the crank..done. Rotate CLOCKWISE s your standing next to the bike.

[paulie2026]

i can see the valve is still open and i can feel pressure on my hand when im spinning the engine. im starting to think my tdc 1-4 is off by alot . anyone have some suggestions for checking this?

[paulie2026]

tdc isnt off im starting to think the chain is off, the intake just will not set right at all based of the roller pin count

[Nessism]

Set crank to 1-4 T. Be sure. Look at the spark advance unit. Remove the Dyna S if you can't see the marks. And don't try to do it by looking for the piston at TDC either.

Pull up on the cam chain in the front (but not so hard that the crank moves) and install the exhaust cam. Make sure the 1-- mark is aligned with the gasket surface.

Count 20 pins between the 2 mark on the exhaust cam and the 3 mark on the intake cam. Double check and then bolt down the intake cam. Don't worry about where the arrows point after installing the idler gear.

Turn over the engine with a wrench to be sure it spins properly. Then set 1-4 T mark and double check everything again.