gpz 550 cams in a kz550 or zr550?

I will only be taking readings from #4 intake and#4 Exhaust Cam Lobes because they are easy to get to. The valves will be checked and gapped within the recommended settings before taking readings. This information should be useful.

Thoughts?

Would be interesting to confirm they are within a few degrees of factory spec , in my testing I got a difference between the different grinds but couldn't get that full 280 degrees from this hypothetical 'zero lift' . That was dial gauge on cam, no shims or valve clearances to alter the numbers. Ultimately the 'real' duration and lift is out of your control. The lobe center timing can be adjusted I guess the important numbers, to me, is the lobe center position,

Tyrell Corp wrote: I will only be taking readings from #4 intake and#4 Exhaust Cam Lobes because they are easy to get to. The valves will be checked and gapped within the recommended settings before taking readings. This information should be useful.

Thoughts?

Would be interesting to confirm they are within a few degrees of factory spec , in my testing I got a difference between the different grinds but couldn't get that full 280 degrees from this hypothetical 'zero lift' . That was dial gauge on cam, no shims or valve clearances to alter the numbers. Ultimately the 'real' duration and lift is out of your control. The lobe center timing can be adjusted I guess the important numbers, to me, is the lobe center position,

The duration at zero lift is way longer than 280 deg. It gets closer to 400 deg. The factory timing/duration specs are at .012" lift, or more likely 0.3 mm.

It's all listed on the valve warning page. Just scroll down to the cam specs. I show the duration at several different lift standards for the purpose of comparing against aftermarket cams.

If the readings for duration from Kawasaki are taken at their minimum valve clearance, then that's great! I wouldn't have expected this, but will check just the same. I won't be taking readings from all cam lobes.

The Web Cam's Degree Link, I posted, has you going through the steps to check cam lift and duration, before setting cam lobe centers. when installing aftermarket performance cams. Performance cams com with the information, giving lift, duration, and their recommended settings for lobe centers. Obviously, lift and duration cannot be changed, so like Brendan says, the lobe center setting is all you can adjust, and this is very important.

Again, duration specs for the factory cams are given at .012" ( .3mm) lift with zero lash.

Another way to say it is if you set the lash to exactly 0.300 mm, the duration will be from when a valve just comes off the seat to when the valve just returns to the seat, and that duration will match the factory spec.

loudhvx wrote: Again, duration specs for the factory cams are given at .012" ( .3mm) lift with zero lash.

Yep I got that from your post above. I'll just take the readings from the valve clearance it is now. I'll not the current gap too.

.012" (0.3 mm) is bigger than the valve clearance.

Using a normal valve clearance (say 0.15 to 0.20 mm) as the lift spec., I would expect the duration to be significantly longer than the factory spec.

The duration at zero lift is way longer than 280 deg. It gets closer to 400 deg. The factory timing/duration specs are at .012" lift, or more likely 0.3 mm.


400 degrees of crank? i was getting from about 210 to about 235 degrees of cam, of various different z and gpz grinds. - so double that for crank degrees. There was a measurable difference between them but I was expecting to get somewhere closer to the listed 248 to 280 degrees. I used a dial gauge, protractor and a couple of v blocks.

This 0.12" factory lift spec is news to me, I guess a road cam has more gentle opening and closing ramps .

Trying to think where my testing may have gone wrong.

loudhvx wrote: .012" (0.3 mm) is bigger than the valve clearance.

Using a normal valve clearance (say 0.15 to 0.20 mm) as the lift spec., I would expect the duration to be significantly longer than the factory spec.

Oops! Sorry about that Lou, I was thinking about the intake's 0.004" and 0.1016 mm for valve clearance. :S

Tyrell Corp wrote: The duration at zero lift is way longer than 280 deg. It gets closer to 400 deg. The factory timing/duration specs are at .012" lift, or more likely 0.3 mm.


400 degrees of crank? i was getting from about 210 to about 235 degrees of cam, of various different z and gpz grinds. - so double that for crank degrees. There was a measurable difference between them but I was expecting to get somewhere closer to the listed 248 to 280 degrees. I used a dial gauge, protractor and a couple of v blocks.

This 0.12" factory lift spec is news to me, I guess a road cam has more gentle opening and closing ramps .

Trying to think where my testing may have gone wrong.

Yes, everything in crank deg unless stated otherwise.
My valve train link shows the lift at .0002", .006", .012", .040", and .050" for all three grinds. That is so you can compare with other Kawasaki cams and aftermarket brands.

I threw the .006" lift in there for those of you who just want to measure duration without taking things apart.

If you simply open the cover, rotate the crank, measure the actual bucket movement, and assuming a normal valve lash clearance (approx. .006" or ( .15mm) ) exists on your bike, the result should be somewhere near the duration listed for .006".

Side note: .006" ( .15mm) is in the mid range for intake, and low end for exhaust, lash. Perhaps .007" would have been a better choice, but I probably wanted a 1/2 of the .012 factory spec to investigate the ramps.

At any rate, it should be somewhere between the .0002" duration and .012" duration.

Since the ramps may not be linear, a linear interpolation probably won't be precise, but it will get you somewhere in the ballpark, of what to expect.

Daftrusty wrote: Y

I also started drawing out the cam timing graphs for the different setups and it quickly became less helpful when comparing the three. So I switched to an online calculator as it made for a better numerical visual aid.

Not very helpful

Actually I like that diagram a lot. Everything's there, or could be with a bit more labeling.

Let me make sure I'm reading it correctly. For the zx, the intake opens 46 degrees before tdc while the exhaust is closing from the last cycle. The intake closes at 54 degrees after bottom center. Then at some point near tdc there's ignition (we have the ignition degrees earlier in this thread - the ignition advances as rpms go up). At this point both intake and exhaust valves are closed. Then the exhaust opens at 64 degrees before bottom. The intake starts to open again at 46 degrees before top. This is the start the "overlap" period, which lasts until the exhaust closes at 36 degrees after tdc. The "duration" is just the degrees that each valve is open, which is visually quite clear from the diagram.

It would be cool to see the diagram animated, spinning around as the engine turns.

Took my bike for a long ride again this weekend. It felt good, definitely better than last time. I'm still planning on doing a dyno run to get some real data to go along with the butt dyno, but one hard piece of data is in - the mileage was terrible again - 33.2 mpg. Was getting 40-45 mpg before the cam swap, sometimes even 50mpg. I wonder if I need to rejet, or if the timing really is off a tooth. Either way, seems like a pretty drastic drop. I'm also noticing some idle issues when the engine is cold, though they're intermittent. I did a cursory check for vacuum leaks. Will do a more thorough check this weekend and adjust the mixture screws. One last weird thing- when starting the engine sometimes I hear a loud crack, not like a backfire "prumpff" but a really sharp "cack!". Seems like it's coming from the front of the bike. Maybe ignited fuel in the headers?

When I go to the leanest jetting for normal running, I can get nearly 70 mpg. But that is only relevant to part-throttle jetting 1/16 to 1/8 throttle. The power range, 3/4 to full, should always be richer than part throttle. So it could be jetting, but the jetting that affects mileage is in a different range than affects power.