1984 GPZ 1100 cam lobe hight

I was wondering what was the factory cam lobe hight for the 84 gpz1100
I got 18.2 mm for all 4 INTAKE lobes AND 18.3 for all 4 EXHAUST
THANKS

I have a 1983 GPz1100A1 Mainenance manual Supplement.
It states that the Cam height In/Out is 37.75mm - 37.85mm with a service limit of 37.65mm.
It doesn't specify where the measurement is taken from.

Hope this helps,

Do you mean valve lift or overall cam height.
The factory manual only gives cam height for service limits which is the overall measurement from the base circle to the lobe tip and will be around the 37.75 etc as previously stated.
Your 18 mm figures mean nothing as i suspect you have measured from the lobe tip down to the camshaft core.
To get the true valve lift, subtract the base circle from the cam height.
Off the top of my head they are in the region of 9mm lift.
I have a set in the workshop i can accurately measure if you need.

Any information on the actual ''cam'' it self will be helpfull. I did measure from the tip of the lobe to the oposit side of the cam lobe. This cam looks worn
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zed1015 wrote: Do you mean valve lift or overall cam height.
The factory manual only gives cam height for service limits which is the overall measurement from the base circle to the lobe tip and will be around the 37.75 etc as previously stated.
Your 18 mm figures mean nothing as i suspect you have measured from the lobe tip down to the camshaft core.
To get the true valve lift, subtract the base circle from the cam height.
Off the top of my head they are in the region of 9mm lift.
I have a set in the workshop i can accurately measure if you need.

Here's how you measure the cams for lift and base circle.

Distance between points marked in yellow = overall lobe height [O.L.H.].
Distance between points marked in red = base circle [B.C.].

O.L.H - B.C = Lift

On those cams the B.C. should = 1.110"
O.L.H will be in the 1.485" neighborhood

1.485 - 1.110 = .375"


Before you assemble the head, take some fine paper and polish out the cam journals. Make sure there are no burrs in the journals in the head, under the cam bearings. At least burnish the bearing inserts with a paper towel or some 1000 paper. Just polish them smooth.

Oil everything and bolt them into the bare head. They should spin nice and free. You don't want drag on the cams.

It's an OK set of cams for a stock motor. The'll get a stock valve lifted to the 82CFM range in a stock GPz11 head. If you degree them, put the on 106 centers. Stock is 110.

Well done Larry. That's the best description I've seen yet.

Also, thanks for the tip on the lobe centres for stock GPz11 cams.

man-of-war wrote: Any information on the actual ''cam'' it self will be helpfull. I did measure from the tip of the lobe to the oposit side of the cam lobe. This cam looks worn
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Still don't understand where you get the 18mm from as the cams core and journal dia is much more than that ?

However here are some very accurate measurements.

Firstly on these cams you cannot get a truely accurate base circle measurement using verniers or micrometer straight across the cam (180 deg) as the quietening ramp begins lift at less than 90deg from closed.
If you use that method you get an approx 0.3mm discrepancy.
For this i used a dial gauge with the cams set up between centers.

Inlet
- overall cam height = 37.8mm.(with micrometer)
- lift = 9.8mm. (With dial gauge)
- Base circle = 28mm.

Exhaust
- overall cam height = 37.75mm.(With micrometer)
- Lift = 9.77mm.(With dial gauge)
- Base circle = 27.98mm.

I get the base circle figure by subtracting the lift from the height.

Hope this helps.

On MY cams the B.C. IS = 1.12''



O.L.H IS ..............= 1.50''


1.50'' - 1.12'' = .380''


I did take your advice Larry and polish out the cam journals The pins for the pistons/conecting rod were very stiff to get into and remove from the piston so he honed the piston and polished the pins.

any other advice would be appreciated with this rebuild. Here's a link of the progress.

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LarryC wrote: Here's how you measure the cams for lift and base circle.

Distance between points marked in yellow = overall lobe height [O.L.H.].
Distance between points marked in read = base circle [B.C.].

O.L.H - B.C = Lift

On those cams the B.C. should = 1.110"
O.L.H will be in the 1.485" neighborhood

1.485 - 1.110 = .375"

Attachment camliftmeasure.jpg not found

Before you assemble the head, take some fine paper and polish out the cam journals. Make sure there are no burrs in the journals in the head, under the cam bearings. At least burnish the bearing inserts with a paper towel or some 1000 paper. Just polish them smooth.

Oil everything and bolt them into the bare head. They should spin nice and free. You don't want drag on the cams.

It's an OK set of cams for a stock motor. The'll get a stock valve lifted to the 82CFM range in a stock GPz11 head. If you degree them, put the on 106 centers. Stock is 110.

Yes pictures work for me!!! great job explaining the cam lift

Nitro Mick wrote: Well done Larry. That's the best description I've seen yet.

Also, thanks for the tip on the lobe centres for stock GPz11 cams.

You would not believe how many tight camshaft situations I find. A little attention to journals and bearings goes a long way.

I just did a KZ head with .500/.470 cams. The head had brand new cam bearings. Still, neither cam would spin free

Reduced friction is free HP and especially, when it comes to cams....very important. You want every opportunity you can have to stack the deck in your favor to allow the lobes to survive....

If you're going to degree the cams. Find TDC before you install them. The job is a lot easier if you put 2 valves in one end cylinder using light springs. Then remove the head and assemble with your running components after dialing them in.

Another thing I found a long time ago is this little trick. I use a shim on top bucket and the little notch for prying out the shims is a perfect location for a fine dial indicator tip to rest in. The lobe won't snag it. It won't walk around like it does when it's on the shim surface. Makes getting the dial indicator in that "just right" position relatively easy.

I looked at your photos. You're doing a nice job.

man-of-war wrote: The pins for the pistons/conecting rod were very stiff to get into and remove from the piston so he honed the piston and polished the pins.

The pins SHOULD be a reasonably tight fit in the pistons so that the pin does not run in the piston.
Removal should be aided by warming the piston slightly with a hot rag or hot air paint stripper to expand the alloy.
Gudgeon pin should be of such a fit that it passes through the little end eye with a very slight drag.
Only in the little end rod eye is where any pivot motion should be as this is the bearing surface.
Ideally the piston should not rotate freely on the gudgeon pin.

well that's not the case today when I picked them up from the shop today.. they move VERY FREELY out of the holes!!! on each piston there are 2 sirclips one on each side that holds the pin in place so to stop any travle of the pin.

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zed1015 wrote:

man-of-war wrote: The pins for the pistons/conecting rod were very stiff to get into and remove from the piston so he honed the piston and polished the pins.

The pins SHOULD be a reasonably tight fit in the pistons so that the pin does not run in the piston.
Removal should be aided by warming the piston slightly with a hot rag or hot air paint stripper to expand the alloy.
Gudgeon pin should be of such a fit that it passes through the little end eye with a very slight drag.
Only in the little end rod eye is where any pivot motion should be as this is the bearing surface.
Ideally the piston should not rotate freely on the gudgeon pin.