need help! valve timing.

ok my problem is this. after replacing all gaskets i an in the middle of putting the head back together again, iv done everything by the book 3 times and it looks like its all right.i marked the cam chain with paint to show the 28 links from the exhaust cam mark to the 28 mark on the intake cam. the fly in the ointment is when everything is bolted down and i rotate the crank, on a full rotation of the cam chain the marks are showing up 2 links back, the timing mark on the crank is on the money and the cams are where they should be but its 2 links behind where it started out every time. is the chain to tight? to loose?(it does not seem loose at all, i have the cam chain tensioner in place. im at a loss....:S need someone to tell me where or if im going wrong. oh its 1975 z1

Are you sure of your marking system? A miscount by one when marking out the 28 links would give you two off on the rotation.

I think?!

KZCSI

im prity sure i have it right there is exactly 28 links between my marks, the first link was on the 28 mark on the intake cam and the 28th link is one link above the exhaust mark to the front of the head, all exactly like it says in t?e manual. like i said it all seems right.

i did the whole procedure again and it still ends up 2 links back, any help please????

I havent tried it, but I am not sure its going to line up after one rotation, size of crank gear, size of cam gears chan length.

I know on some of the older datsun engines they would not line up until there was a specific amount of rotations.


If I am wrong someone will correct me

Maybe I'm missing something here, but where does it say that with each rotation, the same link must always end up on the same tooth on the cam gear?

As long as the 28 mark on the intake cam is always 28 pins from the exhaust cam timing mark at TDC, you should be okay. I don't think there is any requirement that the same pin and gear tooth must line up with each rotation. Am I wrong?

kzstreetfighter71 wrote:

ok my problem is this. after replacing all gaskets i an in the middle of putting the head back together again, iv done everything by the book 3 times and it looks like its all right.i marked the cam chain with paint to show the 28 links from the exhaust cam mark to the 28 mark on the intake cam. the fly in the ointment is when everything is bolted down and i rotate the crank, on a full rotation of the cam chain the marks are showing up 2 links back, the timing mark on the crank is on the money and the cams are where they should be but its 2 links behind where it started out every time. is the chain to tight? to loose?

As long as the cams are always in the right place when the crank is at TDC, it should not matter what the chain is doing. The chain's linear length is longer than the circumference of the cam pulley so the chain's position to the cam gears constantly changes as the crank rotates. I think it would only come back to the same positon relative to the cam gear if the number of links in the chain happened to be an integral multiple of the number of gears on the cam pulley.

As long as the cams are always in the right place when the crank is at TDC, it should not matter what the chain is doing. The chain's linear length is longer than the circumference of the cam pulley so the chain's position to the cam gears constantly changes as the crank rotates. I think it would only come back to the same positon relative to the cam gear if the number of links in the chain happened to be an integral multiple of the number of gears on the cam pulley.

I agree. To test this theory i would turn it over again and see if the marks are 4 links off. or try rotate it backwards and see if it lines back up.

this is what i think but im just afraid that when i bolt everything down, start her up, the chain will slip or snap and the pistons and valves will meet each other in a way they wer never ment to. im like a new mother to this bike i guess? im goin to do the whole thing over again tonight for the fifth time, at least its good practice right?

Becker wrote:

I agree. To test this theory i would turn it over again and see if the marks are 4 links off. or try rotate it backwards and see if it lines back up.

I've always been told NOT to turn the engine backwards. I'm pretty sure I read that in the FSM. I wouldn't advise trying this.

Here's my method that I have performed on my Kz650 more times than I care to remember. Everything should apply pretty close to your Z1.


Pull out the cams. Get #1 and #4 at TDC. Check this by pulling out the spark plugs and looking down through the plug holes to confirm TDC on these cylinder. A flashlight will help when looking down the spark plug opening.

Have a buddy on hand to help out with this next step.

Pull the cam chain tight making sure that it is turning freely on the crank sprocket. Roll it back and forth to make sure there is no kink in the links. If there is a kink it could be the cause of your problem.

Holding the chain tight and spread the chain apart. Gently slide in the exhaust cam lining up the marking arrows to the top part of the cylinder head. Do not let the slack up on the cam chain or it could jump out of position on the bottom sprocket.

Count 28 pins backwards on the cam chain from the arrow marking on the exhaust cam mark and then carefully install the intake cam lining in the arrow marking to the cylinder head the exact same as you did on the exhaust cam.

Install the cam chain top idler gear. You will notice the idler gear will push down on the cam chain when torqued down and the cam's arrows might move slightly. This is o.k. as long as the pin count remains at 28.

Finally, install your cam chain aduster which sits under the carbs attached to the cylinders. Only then should you consider turning over the engine in a clockwise direction by using a 17 mm wrench on the crank lobe which is located underneath the points cover on the driver's right side of the engine. Don't use the electric start or the kickstarter as these will turn the engine over too quickly and if the cam chain has jumped a couple of teeth again you could bend a valve or two.

I would strongly suggest not turning the engine backwards if you feel there is still a kink or a jump on the cam chain/timing marks. If you still haven't got it right by following these steps, you might have a more serious problem like a busted tooth on the bottom sprocket or a stretched cam chain.

Cheers-Colin Firth-Ontario Canada

hey thanks guys and thanks colin, unfortunitly i dont have a spare set of hands but i do have about 3000 cable ties and ill give it one more go with new marks. lets see how it goes this time, im still wondeing about is it normal to miss 2 teath every time or not though?