Project GPz

Well now as of today im the new owner of a 1981 GPz550. Made a deal with my roomate..he wants another Interceptor like the Yellow and Red bikes shown in the pics..the Yellow one used to be his till it was reduced to parts bike status by two dead cyls..so now its the parts donor for the red bike.He found himself another Interceptor for $200 so im basicly giving him the cash for it and i get the GPz. Now that its officially mine its time to post an actual project thread...

Heres some of the initial pics i took of it.





Now From what i have read on here and on different sites the GPz is a hopped up version of the KZ550. Higher Compression pistons and hotter cams from my understanding. This one also has a Supertrapp 4 into 1 on it and soon enough pods will replace the air box to shave some weight. Well that and make it easier to service the air cleaners..besides..pods just look cool lol. Still on the fence if im going to reinstall the small faring or not. More concerned with the suspension and wiring at the moment for that to be a worry...do know its getting new LP signal lights to slim the bike down a bit..going to have to space the front ones out a bit if i reuse the fairing. Enough rambling for now...

Just a question..if this was your project to toy with what would you do with it?

First off: a well-played trade. Bravo!

Second: you have some work to do, eh?

Lastly: I'd go with suspension. Always suspension. Getting a set of 17"s on there would be paramount to my project...then rear-sets and a re-routing of the exhaust (the rear-sets frees up a ton of space and manufactured headers leave huge visual gaps...you'll see)...then cosmetic goodies like paint, an ELR-look seat, mirrors, etc...the cosmetic part is the owner-subjective, so there ya go.

Drive on!!! ...and keep us posted.

It looks very similar to my Z500, only mine has a round light and slower engine!

It looks very similar to my Z500, only mine has a round light and slower engine!

I have considered swapping on an EX500 front end and rear wheel. I know thats the hot trick on the triples..so im thinking it may work on the GPz as well..im going to have to do some measuring to see if i can use the EX triple trees as is or not though..hopefully at the worst i need to swap in some different roller bearings on the neck and as for the rear find out if the KZ rear swingarm matches the H1 rear swingarm in width at the rear...then i will have a better idea if the EX wheel will work back there..have looked at the idea of rearsets..rasik makes a nice set specifically for the GPz. as for the header...well the supertrapp unit is pretty tight against the frame..at the most i may do with it is have it either powdercoated or repainted with high temp paint.

You should check compression and valve clearances. Compression should be in the 180 psi range. (choke open, throttle wide open).

RE carbs:
With pods you'll lose a little pull off the line, but the thing will scream on the highway.

With pods you'll want #98 main jets (stock is 94).

You may want adjustable needles. K&L rebuild kit 18-2462 comes with an adjustable version of the stock needles. Second groove from the top is stock. You'll probably want to go to the third groove from the top. The kit comes with #92 main jets which you could drill to 98.

You should also consider the Dynojet kit #2305. It comes with better adjustable needles (use third groove from top) and #98 jets (along with other jet sizes).

Also, you'll probably want this choke mod to make the choke operation more controllable:
www.geocities.com/loudgpz/GPZchokeScrewMod.html

The 1981 gpz550 carbs (Teikei-22) are simpler than the other years and are easier to tune correctly, but the choke system can be frustrating.

Also, you'll want to check out this site if you haven't already joined:
www.nwsca.com/scripts/gpz_forum_2005/default.asp

Post edited by: loudhvx, at: 2007/09/17 12:12

Thank you for the great info man!..When i start wrenching on that part of the bike im def doing that fast idle screw mod. Going to address the butchered R/R harness first..Since that is this bikes main issue at the moment...Also..The other main issue is the cracked up headlight..which will be replaced with a round headlight and a Puig Cockpit flyscreen..

Dude I bought one of those brand new at a motorcycle show in a mall!! Pushed it out the front door and hauled ass. Fast bike in its day.

Mark Keep pics comming

Heres some more pics of the bike now that i have moved the parts bike to storage and the other bike is at the shop right now for repairs. More or less assessing what it needs at this moment..Which is the Ignition cyl, Gas cap, as well as the seat lock..(mainly due to the key being lost) I might be able to get a key cut from the original ignition lock but i would rather just get replacement parts in those areas...

Anyways on to pics..

what the h*** is the blue bike in the background, Give me your frame!:blink:

i'd use the gpz motor in the blue thing.

Could you list the VIN and Engine Numbers from that bike? I don't think I've ever seen that red on a GPz before. The first color in the set of pictures looks right, but the second set doesn't. Was it repainted?

The blue thing in the back ground is a CB750 Honda powered drag bike project and as for the color..that could be how the light was hitting it at the time..i will try to get the numbers off of the bike later today.