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That sounds a bit too mild to me. I thought the intakes were much closer to .380. If that is the case than they could easily be used as drop in cams for any KZ900/1000 1973-80 just by using a APE conversion sprocket and not requiring any grinding on the KZ head at all. My Yoshimura Bonneville cams that i put in my Z1R had a .360 lift with no head mod requirements.

Me too, thought they were.385.

DFIGPZ wrote:

FYI 1983 / 1984 GPZ 1100 cam specs:

INTAKE CAM .354 lift 238 deg

EXHAUST CAM .338 lift 239 deg

hope this helps.
Barry

The Megacycle diagrams tend to agree with you. I know that the standard "J" series intake cams are about .330 because I just measured them. These came from an CSR, that I just measured. Boy that makes me feel really radical, running .420 intakes and .410 exhausts. with 38.5mm intake valves, on my every day rider.

It is a good drop in cam for Z1 900 or KZ1000 stock Z1 900 cam specs :

INTAKE 327 lift ? 237 dur
EXHAUST 296 lift / 229 dur

also you have to remember 83/84 GPZ 1100 had the highest flowing stock cyl head available, also had to run within the constaints of the DFI system and the factory redline was 9,500 rpm. so in other words it DID NOT need extreme cam size on account of head flow. This made for a wide broad power curve. hope this makes it understandable .
Barry

otakar wrote:

DFIGPZ wrote:

FYI 1983 / 1984 GPZ 1100 cam specs:

INTAKE CAM .354 lift 238 deg

EXHAUST CAM .338 lift 239 deg

hope this helps.
Barry

The Megacycle diagrams tend to agree with you. I know that the standard "J" series intake cams are about .330 because I just measured them. These came from an CSR, that I just measured. Boy that makes me feel really radical, running .420 intakes and .410 exhausts. with 38.5mm intake valves, on my every day rider.

Nothing wrong with that i have 420 lift cams i have done for 900s with 1075 kit ported heads still running SOT retainers W/O issues.

DFIGPZ wrote:

It is a good drop in cam for Z1 900 or KZ1000 stock Z1 900 cam specs :

INTAKE 327 lift ? 237 dur
EXHAUST 296 lift / 229 dur

also you have to remember 83/84 GPZ 1100 had the highest flowing stock cyl head available, also had to run within the constaints of the DFI system and the factory redline was 9,500 rpm. so in other words it DID NOT need extreme cam size on account of head flow. This made for a wide broad power curve. hope this makes it understandable .
Barry

That is the same head I am running on my bike with the .420/.410 cams and oversize valves. Plus my head was also ported quite a bit. Plus it is an 1150 with 11:1s

There is so much confusion regarding the lift on these cams, I was planning on putting them into my bike next month to replace the J cams (just what buda did) but I thought they were .375 lift. In a thread several months ago people measured them at .375, whats the deal?

9am53 wrote:

There is so much confusion regarding the lift on these cams, I was planning on putting them into my bike next month to replace the J cams (just what buda did) but I thought they were .375 lift. In a thread several months ago people measured them at .375, whats the deal?

Install them they are an upgrade from the "J" cams.

According to my research, the "big deal" was an increase of .8mm (.0315")over the standard cam. So at the +/- .328" lift on the stock bikes that would make sense at about .360"+/-. So they definitely would be an upgrade, but just not as much as people thought.

Here is a section of an article from a 1983 review of the engine/bike, where the cams are concerned.

"To go with these changes the camshafts have been reprofiled to give more lift and duration. Both valves now have 0.8mm more lift, and they open six degrees earlier and close six degrees later than before. The valves are also bigger: inlet diameter goes up 1mm to 38mm and exhaust up 0.5mm to 32.5mm, with its angle steepened by one degree to allow this. Uprated springs keep the valves under control; setting clearances is more difficult than before because, with shims now beneath the buckets in the style of the old Z650, the cams must be removed to change them. Other mods of note are hand porting of the inlet tract to smooth out the flow, beefier conrods and an ignition which is now advanced electronically instead of mechanically.

What all this adds up to is a motor in a pretty high state of tune for a big road bike — a motor producing phenomenal peak horsepower at the expense, it must be said, of some low and mid-range grunt. There's precious little doing below six grand, so it's no use pootling along behind a line of cars at about 60mph in top and expecting them to open the throttle and scream past them. Trying just that results in a bronchial slow-progress situation and, if you were expecting instant full-bore acceleration, a terminal head-to-head confrontation with any traffic that might be approaching from the opposite direction.

In other words of one syllable, it don't want to know, John. The revs rise pretty slowly to the magic 6000rpm figure, at which point the various gasses start going where they're supposed to and the GPz shoots forward (you're already doing about a ton at this point, of course) like the street racer it is. And no sooner are you starting to enjoy this sensation than the tacho hits eight grand, the motor breathes even deeper and the speedo rockets on from 120mph to 130, 135 ... and more if you've got the road and the balls to spare."

The last paragraph in that section of article I have experienced every time I punch my bike. My magic # on the streets seams to me about 3000 and on the highway also the 6000. But with my .420 lift cams the bike is brutal. Even with the 2.22:1 gearing I am running when stock used to be 2.73:1 For the short time I ran the stock gearing, I had a hard time keeping the front wheel down on the ground while hard shifting from first to second and second tho third. Even with my gearing the front end pops up while shifting from first to second, if I'm really standing on it.

Look at the bottom of this thread where Tim measured the GPz cams and says .375-.380. The .328 lift may have been the CSR or LTD cams, but I presume the .8mm increase your article states refers to a set of 81-82 GPz cams, or maybe a standard J cam

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