1981 Kawasaki GPz550: Restoration

[chuck hahn]

And how much was taken off each side? And how much is left as far as wear limit per the service manual? I am not familiar with what the original thickness and wear limits on nthe GPZ is so that why I ask.

[srsupertrap]

My GPz 550 hardware was actually in very good condition from the axles up but after being inspired by Ed's plating results I decided to replate the hardware and push out the completion date. I contacted Specialty Plating (ISO 9001:2008) in Denver and spoke with Heather the Shop Manager. She told me they handle lots of enthusiasts jobs and they recently installed new tanks and recertified their zinc plating process. She confirmed type I finish would produce a bright zinc finish. I dropped off 340 pieces of hardware which was plated to ASTM B633 Type I Clear Zinc

Before:






AFTER

[jwhelan65]

Very nice! Maybe a dumb question but is there a build up on the threads? What happens when you tap a screw?

[srsupertrap]

By build up on threads . . . . your worried if a bolt/screw is "replated" the M6/M8 thread major diameter will be significantly larger than a OEM bolt/screw which when installed will strip the mating threads?

If that's the question, the plating shop strips the metal part by washing them removing the original finish. The bolt/screw is now back to its machined dimensions. Ed did this by dunking his hardware in phosphoric acid & then wiring wheeling the hardware. Most plating shops have this process automated. When I asked the Plating Manager should I strip all the hardware in phosphoric acid before dropping them off she said don't bother. If you go the commercial route understand the plating shop capabilities, i.e. do they have barrel tumbler & do they certify their work to ASTM or MIL-Std. She did add Dawn dish detergent is one of the best degreaser out there for what its worth

[psyguy]

And how much was taken off each side? And how much is left as far as wear limit per the service manual? I am not familiar with what the original thickness and wear limits on nthe GPZ is so that why I ask.

I'm wondering the same. When I enquired from a few shops locally I was told the rotors (GS850 in my case) don't have enough meat so grinding them leaves them below the serviceable limit

[Nessism]

The KZ rotors are fat, grinding on them should be no problem.

Plating looks good Steve. I've yet to experience any issues with too much plating thickness in the threads on my stuff. Take a nut and try to spin it onto a matching bolt to test.

[psyguy]

T I've yet to experience any issues with too much plating thickness in the threads on my stuff. Take a nut and try to spin it onto a matching bolt to test.

I've had some OEM bolts/nuts triple chromed and still there were no issues. Obviously, zinc plating is a lot thinner so no worries

[psyguy]

By build up on threads . . . . your worried if a bolt/screw is "replated" the M6/M8 thread major diameter will be significantly larger than a OEM bolt/screw which when installed will strip the mating threads?

I thought the OEM bolts/nuts are Metric, no?

[Nessism]

I thought the OEM bolts/nuts are Metric, no?

They are. Thus the M6 and M8 comment, which references metric.

[srsupertrap]

I thought the OEM bolts/nuts are Metric, no?

Yep you are right, it sounded right when I wrote it. Although the PO did install 1/4-20 bolts in the cam bearing caps.

Changing subjects, the local powder coater will be done with the wheels early this week. I have a new set of bearings to install but have not decided on a set of tires. Big T suggested sticking with Avon's which is a sure bet but I noticed the Pirelli Sport Demons are bit cheaper @ Dennis Kirk. Didn't Renobruce use a set of Sport Demons on one of his GS1000's . . . don't recall his experience with them.

Any other opinions/experience with the Pirelli's Sport demons?

[Nessism]

I put Conti Go's on my 750. No personal experience with them but Continental don't make junk. They were the cheapest of the top brands at the time I shopped too.

http://www.americanmototire.com/catalog/index.php?cPath=33_108_871

CONTINENTAL CONTI GO 4.00-18 M/C 64H, REAR $92.55

CONTINENTAL CONTI GO 3.25-19 M/C 54H, FRONT $77.76

Sub-Total: $170.31 + free shipping

[psyguy]

My experience with Sport Demons is that they are rather soft compound (compared to Metzeler that I typically use).

Choice of tyre is also dependent on how / when you ride.

Both Bridgestone and Pirelli I tried had better traction when cold and in the wet but the centre of the tires wore out too quickly compared to Metzeler. With properly inflated and warmed up Metzelers I never had any slippage even when pushing the GS850 to the limits and they gave me better mileage than either Bridgestone or Pirelli.

We don't get Conti's here I don't think.

[tkent02]

I had a Sport Demon on the front of my 650G, it was sticky but I couldn't really test it aggressively, there was a Spitfire on the back, it was not so sticky.. When I finally put the Roadrider on the back the Sport Demon was pretty worn, but it was still plenty sticky.

I would be happy with a pair of either one.

[nvr2old]

I have Conti "Blitz" tires on my S model. I like the round profile on them but I'm a bit disappointed in the handling. They never feel completely planted..not the most confidence inspiring tires. The best tires I ever had were Michelin Macadam 50's. LOVED those tires. Had them on every bike I owned. Can't seem to find them anymore which is why I went with the Continentals on the S. The Avon Road Riders on my 400F seem very good so far, too.

[srsupertrap]

And how much was taken off each side? And how much is left as far as wear limit per the service manual? I am not familiar with what the original thickness and wear limits on nthe GPZ is so that why I ask.

Chuck,
There is no perfect solution because Kawi OEM discs are either not readily available or they cost $250. The next option would be to find a used one on EBay and hope for the best. Next spendy option is aftermarket manufacturers but that could quickly top $500 if you replace all three discs and then they don't look original. . . So to answer your question

Specification Limit 6.00mm
Rear Disc (Now): 5.38mm

I am happy with my decision and will remember to use the front brakes more often.