Heads

Whats the diff. between a j and a gpz1100 head.wich is better to put on a kz900 botom.

81 Injector holders cast into head. Do not know what combustion chamber looks like, suspect it's the same as the J.

82 same as J except for tapped hole for CHT sensor. This I do know, having both.

83/84, I have read, has a different combustion chamber, bathtub instead of hemi, shape but I have not seen one.

Still have not had a chance to get to the workshop since returning from HI 2.5 weeks ago. Linda gave me an arm long list of chores to have done before she arrives in Dec. Mostly plastering as the fist thing on the list and need about 10 min every hour to give arms a rest. By the time I get fast at it, I'll be done

did you say you have to give your arms a rest so you can get plasterd?that must be one heavy bottle.:blink: :silly:

I just wondered if one was to build a new head wich one would be the best to start with.and why

You can plumb nitros into the gpz head through the F/I ports! :ohmy:

donthekawguy wrote:

You can plumb nitros into the gpz head through the F/I ports! :ohmy:

Only 81 has ports in head.

mark1122 wrote:

did you say you have to give your arms a rest so you can get plasterd?that must be one heavy bottle.:blink: :silly:

32oz Modelos in those 5lb Mexican Restaurant mugs

Seriously, I'm replacing the rotten skim coat on 80 year old plaster walls. Take it off with a plane. Put it on with a trowel. Sand out trowel marks. The more plastering I do, the better I get. Result is less sanding as the project progresses. Arms will be in good shape for painting

The 81-82 heads had basically the same combustion chamber as the J head, and the same size valves.

The '83-84 heads are the bathtub chamber and slightly larger valves.

As for which one to put on a KZ lower end?, Use the early hemi style. The reason is that you can use J/GPZ pistons and a .040" spacer plate and have the correct piston dome to match the head. If you use the 83-84 head you can't do that as the 83-84 pistons have 18mm pins.

Jay

ANY MORE INFO ON THIS? "You can plumb nitros into the gpz head through the F/I ports!"

i would prob do it just for looks as i doubt i can get over 120 here anyway.

as i have the head in question on my elr.

A couple of other points about the heads....

83-85 GPz / 84-85 LTD - Intake runners are considerablly larger with the largest intakes and exhaust valves Kaw used on any of their KZ or J motors. Outflows on avg 10cfm @.400" lift /10"Pressure] more than KZ or J. 82 vs 72

Standard J head from any model exclusing above, 1mm over valves, runners are larger than KZ but on average doesn't flow anything to write home about..Low 70s at above test pressure and lift.

J series heads require less work when 33mm or larger carbs are your target size.

Post edited by: larrycavan, at: 2006/11/15 16:59

Since the 83/4 heads flow better that sounds like the best head.is jay saying that you cannot get pistons to work with this head or just cant use stock stuff?

The 83-84 GPZ pistons use 18mm wrist pins. Your KZ and J pistons have 17mm wrist pins. So to use GPZ pistons, you'd have to use a GPZ crank which has a different cam chain style which means lots of changes. I think you could use KZ pistons but the chambers and piston domes would be very different and would require a lot of piston dome work...if it would work. Easier to just use what Jay said.