1984 GPZ1100 Rebuild

BINGO.

dohc wrote:

650ed wrote:

eofa wrote:

Nebr_Rex wrote: Looks like Wiseco pistons. The head is silver not black, got a pic of the combustion chamber?

Combustion chamber? Did you look at all the pics?

Yes. So can you show a pic of the combustion chamber? Ed

Just to add a few more words, I believe what everyone would like to see is the cylinder head combustion chamber in the area around the valve seats. I believe the GPZ had a superior combustion chamber, with a bathtub cutout, while the J model head had the traditional hemi chamber. Since the head it not black, I think Nebr_Rex is concerned that it may not be a GPZ head.

Like this one.


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How's this.

Yep, that's it. Judging by the shim on top buckets and silver paint you have an LTD
head. Same as the GPz except the buckets. Have you measured your cams yet to
see what you have? I.e. GPz, LTD or aftermarket.


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Haven't measured the cams yet. What measurements should I be looking for to determine what they are?

Lobe lift.


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I have a set of GPz11 cams and even better a set of Kenny Harmon cams that will make it run even better. Holler if you're interested.

Riddle me this one. I just measured the cylinders. I'm getting:

#1 - 74.43mm
#2 - 74.55mm
#3 - 74.49mm
#4 - 74.57mm

Correct me if I'm wrong but doesn't that mean it already has an 1170 or 1135 big bore done to it already? The stock is 72mm and the Wiseco 1170 pistons are a 75mm and the 1135 is 74mm.

Stock bore and stroke are 72.5 x 66.

r2 x π x stroke x no. of cyl. = c.c./c.i.


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I measured the cam lobes today. 37mm. Are those stock or aftermarket?

Other good news. My buddy and I who has a full service motorcycle shop picked up a Hydro-Hone wet blast machine. It needs some parts so hopefully it will be up and running this month. I'll post some pictures once we blast the heads and other parts. Once it's up I can offer this service to the forum.

It's almost the same machine as this:

Lobe hieght minus base circle diameter equals lobe lift.


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eofa wrote: I measured the cam lobes today. 37mm. Are those stock or aftermarket?

The stock base circle is 1.110". Your 37mm is 1.457", which leaves a lift of 0.347". I believe the stock cams have a lift of around 0.375", so maybe your measurement isn't accurate enough?

Anyway, those are likely the stock cams...