1981 Kawasaki GPz550: Restoration

[Cipher]

I am betting that bit of rust is doing nothing negative.

[srsupertrap]

Ed,
Thanks for sharing your KZ charging issues and your experiences with resolving it. Didn't realize you had all those problems. Since I have a used EBay generator flywheel enroute I will give that a try. I am also going to clean up the stator pole corrosion seen below on the original stator before testing. Not sure if corrosion would reduce VAC output or not but electricity likes clean contact surfaces. Curious did you check the Rick's for VAC output?



If the flywheel arrives this weekend and if the VAC & charging voltage are still below spec. I will just order the Rick's that same day. The KZ550 & KZ750 might share the same stator P/N too.

[Nessism]

Steve,
You are experiencing a very similar situation to what I went through with my KZ. I tried two different used stators, three different R/R's, and still couldn't get the charging voltage up. Finally bought a new Rick's stator and SH775 and bang, 14.5 VDC @ 5000 rpm.

[srsupertrap]

Spent more time T/S the GPz charging system this last weekend and found some interesting findings, eliminated several issues but didn?t resolve the low charging problem. First, I checked the resistance between the three stator leads and ground. The resistance value should be open; I verified all three leads read ?OL?.

Then I performed a meter test on the Shindengen SH230 R&R per Electrex World T/S chart. First I disconnected the R&R and selected the DMM diode setting. I tested the R&R by connecting the positive lead to the R&R ground wire and used the black lead measure the three R&R stator wires. Per the T/S chart the voltage reading should be between .35 to .75V. Then connected the black lead to the Red R&R wire and used the positive lead to test the three R&R stator wires. All six R&R measurements were between those values (.491 - .502V).

Next I checked the stator resistance. The Kawasaki service manual states the resistance between the 3 yellow stator leads should be .32 to .48 Ω. I cleaned all the stator terminals to shiny metal before taking measurements and measured .6 to .7 Ω on every lead combination.
]

I then checked the meter lead resistance and that measured .1 Ω. If I subtract .1 from .6 I get .5 Ω close to factory spec but still higher.

Next stator output, the table from the Kawi Service Manual shows I should have 75VAC @ 4K rpm. I disconnected the stator leads, ran the bike @ 4K rpm and measured VAC between the three stator leads. My test results were 52-56 VAC much lower than the Factory Manual by some 20%.

]

Feeling hopefully I pulled a known good stator from the 82 GPz550 rolling chassis I bought in Colorado Springs for $150. Cleaned up the leads, added new rubber connectors, carefully installed the stator it and got the same exact test results of 53-56VAC.


Since the VAC output and resistance between the stator leads was identical for two OEM stators shown I can only conclude the generator magnets on the flywheel I have installed must be weak. What else could account for the same result when measuring VAC output between the three leads pictured above. I ordered a good looking KZ550 generator from Ebay should be here 7/31.

[Nessism]

The factory R/R is a robust Shindengen unit. Most likely your stator is weak. I had the same problem with my KZ. On my bike the no-load AC voltage was high but the charge voltage never got above 13.7 V or so. I spent a lot of time chasing my tail because I assumed because the stator was showing high AC voltage that it was good. False assumption. A high no-load voltage doesn't mean your stator is strong, but a low no-load voltage does mean the stator is bad.

Regarding an SH775 harness, Triumph sells a very nice pigtail that can be easily modified for use on your bike. P/N T2500676

[srsupertrap]

Disconnected the 6p connector and checked the GPz550 R/R Wednesday night The diodes checked out with the DMM per the Factory Manual T/S section reading(1.5M to 1.8 M Ohms) in one direction and open in the other. The SH775 may be an upgrade I look at in the future after reviewing threads on the topic and learning about connectors.

I will check the stator output between the three leads tonight, difficult revving the engine to 5k and juggling the DMM leads.

[Nessism]

Get a SH775 and slam that in straight away Steve. You can find good used units from ebay for $40. Eliminates one headache.

[srsupertrap]

7/16 Update: The GPz550 is carbureting very well but the charging system output across the battery is weak making idling aproblem. Before going for a ride last night, I checked the battery charging voltage with a DMM. I was reading 13.5 volts across the battery @ 4k RPM but it took a while to creep up to 13.5 Volts. When I returned from a five-mile ride I took more DMM measurements across the battery terminals. At 2k RPM, I am reading 12.8 Volts across the battery. At 4k RPM, I am reading 13.1 Volts across the battery with a Digital Multi Meter so while riding the battery is being drained. Per Factory Manual its exactly like a Suzuki GS, at 4k RPM it should be around 14V so obviously either the Stator or R&R is marginal. The GPz550 has a Shindgen R&R six wire with the sense wire connected to "+" terminal. I did run an additional ground from the R&R ground directly to the battery ground on the engine case.

Looks like I have to check the R&R diodes and stator output but any other suggestions?

[srsupertrap]

Step at a time, eh Steve? This bike is so cool, it deserves the love and attention you've devoted to it. That pipe looks very similar to a Kerker. Should look and sound great when installed.

Larry, You're right, one thing at a time and if you don't do it right the bike lets you know. During the week I went over the R&R and stator wiring. The charging system is exactly like a later GS model. When I went over the wiring harness originally, I knew one of the three stator wires had overheated and was stiff. I cleaned the connection with a drill/wire brush and moved on. Although the resistance was low on all three stator wires from this picture to the stator electrical connections, I decided to replace the connector on the left.



I cannibalized the exact same wire and stator connector from the KZ550 wiring harness. Then decided to use KZ550 six wire connector too. The R&R wiring was all good but I noticed the ground wire from the R&R disappeared into the main wiring harness. If I have learned anything from reading Posplayr R&R threads over the years its that adding a ground leg to the R&R (-) and running the additional ground to the same point where the Negative battery cable is grounded is beneficial for charging health. Not sure if that is power grounding but I performed that task too. Here is how the repaired stator connector looks. I buttoned up everything and I will test the charging circuit Saturday morning.

[nvr2old]

Step at a time, eh Steve? This bike is so cool, it deserves the love and attention you've devoted to it. That pipe looks very similar to a Kerker. Should look and sound great when installed.

[srsupertrap]

Weekend Update 6/24/18:

I don't give up, I just don't have enough time. The spark plug pics in #463 were the Accel (NDs) which I ran with the 32.5 pilots. I used the same plugs for a carb synchronization so they got very discolored. I decided to start from Step 1 and installed a new set of NGK D8EA's and see how the GPz ran. Cleaner but the carburation still surged. Back at the garage, I turned all the air screws to 1 turn out.

Took another test ride and what a transformation. First the GPz started immediately and idled on its own. Second it pulls cleanly and hard out of corners even under 3K rpm. The engine idle was set way way too high with the air screws at the right setting. It was idling at 4K rpm which tells me how far off the previous setting were. I now had some confidence to ride the GPz on the main road, after twenty miles the spark plugs looks like this so I am feeling pretty good the Mikuni Smoothbores are viable. Even better I don't have any engine oil leaks.





I would like to thank Roger (Burque73) for helping me find a KZ550 Vance & Hines 4 into 1. Roger heard of a guy named Greg through one of his friends who has several 1981 GPz550 parts bike. I finally contacted Greg and purchased this rusty but undented Vance & Hines for a great price. Light sand blast, followed by VHT will transform it back to life . Hope it gives me center stand access again.

The only bad thing during the ride was my MotoBat battery nearly died so now I have charging T/S. Strange I know I saw good voltage with the DMM across the battery terminals.

Still hanging in there Steve? Keep at it you are getting closer. Might need to invest in a Wideband System for tuning. Check out this:

https://www.innovatemotorsports.com/products/db.phpi

[GS1150Pilot]

Fantastic sound!
Be rightfully proud of a job well done.

That makes me miss my '82 badly. I had a Kerker on it, and it sounded wonderful, too. What a stunning bike!

[srsupertrap]

Wow, great job. Really cool bike! How did the 30 pilots work?

Took a test ride around the neighborhood today with the 30 pilots installed and air screws 1.5 turns out from seated. Better, but still not right.

Issues:

• Still won't idle or start when hot without giving some choke.
• Will stall when approaching stops.
• While on the pilot circuit and the throttle closed the GPz surges as engine rpm drops.
• Above 3500 rpm when timing is fully advanced the engine hangs up @ 3500 -4000 rpm ??? Note: Short shifting is much better but its not rideable in traffic.
• Right fork seal leaks

Verified the timing and spark plug gap was correct afterwards. After 12 miles the plugs look like. I ran these same plugs with the 32.5 pilots and they were pretty fouled. The Flatslides have Push / Pull thottle cables like VM equipped GS750/1000s. Both cables have slack and the throttle spring snap the slides shut. Thoughts?

[Nessism]

Bump for a ride report!