GPZ 1100 CAM HEIGHT

I was wondering if the O.L.H Cam Height of "37.50mm" OR "1.47 inches" is the culprit for the lack of performance on this 84 GPZ 1100. The standard Overall Lobe Height on these cams is 37.75mm or 1.48 inches TO 37.85mm or 1.49 inches. ANY ADVICE ON THIS GUYS?

Thanks

The 1981-1982 cam specs are:

GPZ1100 B1/B2 Cam Specs


1981 KZ1100 B1 Gpz:

Intake:

Duration: 280 - Lift: 8,4 mm - Open: 35 BTDC - Close: 65 ABDC

Exhaust:

Duration: 280 - Lift 8,8 mm - Open: 68 BBDC - Close: 32 ATDC

I'm not 100% sure, but I think these cams are also used on KZ1000J/R1 models.

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1982 KZ1100 B2 GPz:

Intake:

Duration: 288 - Lift: 8,8 mm - Open: 34 BTDC - Close 74 ABDC

Exhaust:

Duration: 288 - Lift: 8,8 mm - Open 72 BBDC - Close 36 ATDC

I believe these cams are also used on the KZ1000R2.


I'd ask Larry C about his take on the cam heights....

I do need to know if the shortage of material off the cams will effect the bikes performance. Is their a part # I could get for a mild STEP UP from a factory cam ?

man-of-war wrote: I was wondering if the O.L.H Cam Height of "37.50mm" OR "1.47 inches" is the culprit for the lack of performance on this 84 GPZ 1100. The standard Overall Lobe Height on these cams is 37.75mm or 1.48 inches TO 37.85mm or 1.49 inches. ANY ADVICE ON THIS GUYS?

Thanks

a] 37.75 mm (overall height of lobe [includes base circle])
b} 28.19 mm (base circle of 1.110")
*] 9.56 mm (lift in mm = .376" {a-b})
c} .15 mm (max lash = .006")
9.41 mm (net lift = .370" {*-c})

37.75 - 37.50 = .25mm = .009"{measured difference posted} would reduce net lift to .361"

Just exactly what kid of a performance loss are you experiencing?
Is it still injected?
Did someone :evil: trash the injection in favor of a wonder rack of BS34's

Even at .361" lift, the head, if stock, is flowing the same as it does at .370" lift. However, if the cams are worn they are also loosing some duration. Still, that minor amount wouldn't account for a real big performance hit.

Without ever hearing it run or seeing knowing any specifics, it's not realistic to pin point anything. I suggest a compression check to start with and verification that the cams are installed correctly.

Hi Larry,
The performance is not all that bad but from what I can remember 28 years ago my new GPZ 1100 was a little more performancy than this bike. I'm not sure but the 28 year old cam lobes could be one of the problems, as it falls into and below the service limits of 37.65mm.
Maybe the duration of how long the valves stay open could play a roll in the lack of performance.
This engine was rebuilt 1500 Km ago. I installed new rings, clutches and springs and dialed the valve clearances between 12mm to 15mm.
The engine builder also PORTED THE INTAKE AND EXHAUST ports on the head. Not sure if by porting the head it sacrificed my pull offs.....

I know a guy with a good set if you're interested. Probably could be had for a buck and a half. PM me if you want them and I'll get you his phone number and name.

Thanks for the link with the cam offer Larry.
I would like to try a mild street performance cam,a step up from the factory cam. would you be able to find me something used ? Or a part # ?
Thanks

Most mild street cams are very similar to the cams you have now.

The cams you'd notice a difference from with a good port job would also require springs, performance buckets and pistons with enough valve relief for clearance.