79 twin timing help

Hey guys.. I need help timing a 79 twin I just picked up. My friend had it and had taken the top end apart to replace a gasket leak. I've searched everywhere and can't find the info I need. I have a manual on the way but can't wait that long.
The marks on the cam sprockets... Do the arrows point to the front and the straight lines to the rear? They need to be level with the head correct? How many pins do I need to count on the chain? Do I do this with the chain tensioner in place?(not sure how tight)
The marks on timing advancer... From left to right I have a F,line,line,T. Which line do I line up with the timing mark?
If anyone has any pics of my timing needs can post them.

Thanks for your help.

Hello cnyl, while I don't have the answer to your question. It would be easier to answer if you provided which twin you're talking about. Either in your signature or in the message.
Thanks, Tony

If it is a 750 twin (I think all KZ's use the same mark), the F is the base timing mark (static or idle setting). The T mark is TDC, used for setting the cam timing.

Cam timing:
Align the arrow on the intake cam with the top rear edge of the head. Starting with the upper pin on the link that coincides with the inlet camshaft sprocket arrow mark, count to the 32nd pin, and align that 32nd pin with the arrow mark on the exhaust cam sprocket.

Assuming it's a 750 twin anyway, but it would really help if you would specify.

Thanks guys. It's a 79 kz750 twin.

Steel, Do I align the cams while the cam chain tension adjuster is out of the bike? If I need it in how do I know when it's tight enough?
On the exhaust cam sprocket there is also an arrow with 32 stamped near it. ?

Cam tensioner needs to be removed or it will be virtually impossible to move the chain.

Is there more than one arrow stamped on your exhaust sprocket? I thought there was only one, and the 32 is the number of pins betwwen the two arrows (intake and exhaust). And don't forget that the twins turn backwards compared to the fours (counterclockwise looking at the points side).

Yes there are 2 arrows on the exhaust cam. One that has a 32 stamped near it and the other that is on the opposite side of a straight line. I lined up the IN cam like you said. I then lined up the EX cam using the arrow that doesn't have a mark. I went back to the IN cam mark and counted 32 pins. The 32nd pin end up being at the arrow with the 32 mark. Around two o'clock
ish.

alright heres a question... put the exhaust cam on the intake side how would you time it, heres why I have a friend at a german site told me this....."There is another Z 750 webside, www.twinbikes.com . In an older issue Peter Paulus, the guy who does that webside reported that you will get about 65 hp instead of 50 by using the the output camshaft also on the input valves. Output camshaft has two mm#s additional lift and therefore that might be possible, he had also shown a measured performance chart of the engine on the webside. About a year ago I phoned with him about some other twin details and he confirmed fully the improvement."...I have a new exhaust cam and intend to install it on the intake side

Post edited by: agawam, at: 2006/04/28 23:31

Agawam, I have been giving some thought to this ever since you mentioned it to me, and the best answer I can come up with is to use the intake cam sprocket on it and time it as stock. Now this very well may not be the "best" answer, that requires experience with varying the cam timing to determine what timing will give the maximum benefit. I have some spare cams and motors here, along with a dial indicator and degree wheel, so I think I'll probably do some investigating and get back to you on the results.

I just took a quick look at the specs, and the exhaust cam also has 20 degrees more duration than the intake.
Based on the timing specs, it looks like the extra 20 degrees will all be BTDC, so I'm assuming the power increase was at higher rpm's. Unless Intake length tuning is done, I think using the stock intake sprocket and stock timing is the best answer.
Sheesh, the intake tuning will take some calculating, and it's not like I don't have enough to do already

I wonder how much more benefit you would find with increased compression, and porting the head?

I do tend to get carried away

I looked at the twin website, and it looks like the motor had 67 hp, ported head, Stage 4 carb kit, and two into one exhaust with a SuperTrap muffler.

Post edited by: steell, at: 2006/04/29 05:31

agawam, you really started something here!

Got me thinking, ok I have all these spare parts so I think I'll try the exhaust cam in the intake position and see how it works.

So I pull the cam cover and the intake cam, and I think, "Well, since I'm here I might as well take the head off and lap the valves", so I pull the head. Now I think "Hmm, got the head off, might as well remove the jug and pistons and stick on a jug with a fresh .040" overbore and new pistons, since they are just sitting there on the shelf".
Then I start thinking "Hmm, .040" overbore, new pistons and rings, exhaust cam on intake, sheesh, maybe I better port the head too".

Now, after all this, I don't have any carbs that will handle the mods, so now I have to put the EFI stuff that I have been saving for the GPz750 on it.

And the only reason I started working on it at all was to change it over to electronic ignition, which I still have not done yet!!

Sheesh :laugh:

Post edited by: steell, at: 2006/05/04 02:48

roflmao it happens lol ive ben there, got several projects in the works lol been there lol been there:woohoo:

anybody have pictures handy?