I believe KAWASAKI Service Manual timings to be correct . They are doing these timings for 17-18 years now . I donīt think they want to bullshXX anyone .
I believe 720/34/2 = 10.58 in any math ( even Cantorīs )
Speaking of thinking outside the box , whatīs up with the link to WebCams ?
Anybody can BUY an aftermarket cam or a bigger cilinder , but thatīs inside the box .
If you need accurate measuring , donīt trust Kawasaki or not sure of divisions , youīll need to buy your gear and do your own measuring .

 

Changing cam timing has NO direct effect on how close the valves come to the top of piston. If the vavles were too close, the day you brought the bike home they would hit the piston the first time you started it. This doesn't increase lift.

 

this happens if the piston hits the valves...

 

Ray , Changing the timing doesnīt modify the lift , BUT if you go to wild on the cam timing ( 2 teeth or more ) you may touch the piston top because the cam is pushing it at the wrong ( wildly alterated ) time . It has nothig to do with changing or not the lift .

 

Wow EMS , the poor head , it looks like it was young too ... RIP .
Thatīs why : Please exercise great caution when doing timing stuff , check and double check your positions , tensioners , use threadlock on the cam bolts and donīt be ashamed to ask if you didnīt understood something .

 

Ray,

Moving the cam timing absolutely changes the valve to piston clearance. If the valve were held fully open at TDC in OEM form, then the change would not matter. Typically, on any engine I've dealt with the valve is already over the nose and receading as the piston is coming up to TDC. If you change this valve timing so that the valve is later to close as the piston nearing TDC then the valve is closer to the piston.

As the piston comes towards TDC just prior to the intake stroke, the valve begins to open, actually before the piston passes TDC. The valve starts to open and the piston is being moved lower in the cylinder creating the suck that fills the cylinder. As the piston travels down away from the valve head, the valve reaches the peak of the cam lobe and it noses over and begins to close. This happens as the piston is slowing down and nearing the BDC.

Same type of situation happens with the exhaust valve.

As you manipulate your cam timing in respect to crank timing, you change the relationship of the valve to the piston, thus the very reason we clay our engines and hand rotate them. If you go *****-nilly moving things and there is not enough design clearance in the assembly you risk KABOOM. Also on a canted valve design where the valves actually occupy the same space at full extent, when you move the lobe seperation angle you can allow the valves to collide. I've done this

I've not really seen a KLX head to know if it is a canted design or not, but I know that the cam timing ABSOLUTELY effects the valve to piston clearance. I've built an engine or two in my time and I've made the mistakes that cost the race or end the season early. It usually comes with an impressive price tag to repair the error.

 

Yes, you're correct to not necessarily trust Kawasaki or any other manufacturer's cam timing out-of-the-box. Most all of them use the "close-enough" method which is practically always...well...close enough. You have to slot the cam sprockets a tiny bit to achieve perfection usually, and for a bone stock engine this just isn't normally worth much effort. I was just thinking that precisely degreeing the cams in the scenario that you have discovered may be worth it. As the Web Cams info indicates, this can be a valuable tuning element. Like I said, not poo-pooing your effort here whatsoever.

Someone with a lot more tuning and model knowledge than I brought something to my attention. Apparently there may be a similar issue that occured with the Yamaha YZ400F/WR400F series and the YZ/WR 426 series cams as far as tuning the cam timing goes. I haven't started looking for it yet, but perhaps it would shed some light on Marcelino's approach in this case.

 

EMS,

What is that head from, your KLX?

 

D'oh..... lol (Im used to non-interference fit engines) you are correct, I definetly spoke out of turn.

Working on 80's turbo-mopars for 13 years will do that...

Note to self lol...

 

If my thinking is correct, advancing the intake buys you more space. You are withdrawing the valve earlier in ralation to the piston that is speeding up the cylinder at the open valve, thus getting the valve out of the way even earlier than you were with the cam set up OEM.

The side that I would be interested in seeing someone measure (clay or similar) is the exhaust. As I understand it you are saying to retard the exhaust cam, so as the piston is racing up the hole at the open exhaust valve, when the factory setting would be pulling that valve in towards the closed position, you are now holding it open until the piston is up higher in the bore and thus reducing the design exhaust valve clearance.

Now, if the OEM clearance was very large, this is likely not of any issue to anyone. But... if they were cutting it close, your now cutting it much closer.