1981 Kawasaki GPz550: Restoration

[srsupertrap]

Putting out a request/feelers for for a unmolested 1981 GPz550 engine/bottom end. The PO clearly parked this GPz550 when something broke internally. The carbs were never drained, piston blow by, black oil etc

The cam chain is also stretched because the PO installed a mechanical cam chain tensioner & then tightened it a little bit more just to be sure. . Couple that with my clutch hub debacle and the yet unknown root cause of why it was sidelined to begin with and you get the idea as the cash register continues to go ka ching, ka ching.

I had a dream last night . . . I picked up that GPz motor and lifted it over my head and threw it into the dumpster. There I feel better

[rustybronco]

The hub turns the transmission.

Throw it over your head to the scrap metal dealer. At least then you get paid (somewhat) for your troubles.

Could be worse. My GS1000EC needed a crankshaft, starter clutch and the flywheel.
(By the way, every time I go downstairs, I enjoy looking at those pipes!)

[Nessism]

Try this one Steve...http://www.kawasaki.com/DefaultFrame...HOWVEHTABS%3d1

The Gpz550's had issues with crank/rod bearings failing. I'd stay the course with splitting the cases and inspecting the innards. Less risky than purchasing some unknown lump of a bottom end. You should be able to find that clutch basket piece for less than $25.

My earlier info linking that part to the 750 twin was wrong, I believe these are the models that shared that part with the 550...


EN450-A1 (454 LTD) (1985)
EN450-A2 (454 LTD) (1986)
EN450-A3 (454 LTD) (1987)
EN450-A4 (454 LTD) (1988)
EN450-A5 (454 LTD) (1989)
EN450-A6 (454 LTD) (1990)
EN500-A1 (Vulcan 500) (1990)
EN500-A2 (Vulcan 500) (1991)
EN500-A3 (Vulcan 500) (1992)
EN500-A4 (Vulcan 500) (1993)
EN500-A5 (Vulcan 500) (1994)
EX500-A1 (EX500) (1987)
EX500-A2 (EX500) (1988)
EX500-A3 (EX500) (1989)
EX500-A4 (EX500) (1990)
EX500-A5 (EX500) (1991)
EX500-A6 (EX500) (1992)
EX500-A7 (EX500) (1993)
KL600-A1 (KL600) (1984)
KL600-B1 (KL600) (1985)
KL600-B2 (KL600) (1986)
KL650-A1 (KLR650) (1987)
KL650-A2 (KLR650) (1988)
KL650-A3 (KLR650) (1989)
KL650-A4 (KLR650) (1990)
KL650-A5 (KLR650) (1991)
KL650-B2 (Tengai) (1990)
KL650-B3 (Tengai) (1991)
KZ550-A1 (1980)
KZ550-A2 (1981)
KZ550-A3 (1982)
KZ550-A4 (1983)
KZ550-C1 (LTD) (1980)
KZ550-C2 (LTD) (1981)
KZ550-C3 (LTD) (1982)
KZ550-C4 (LTD) (1983)
KZ550-D1 (GPz) (1981)
KZ550-F1 (Spectre) (1983)
KZ550-F2 (LTD Shaft) (1984)
KZ550-H1 (GPz) (1982)
KZ550-H2 (GPz) (1983)
KZ550-M1 (LTD Shaft) (1983)
ZR550-B1 (Zephyr) (1990)
ZR550-B2 (Zephyr) (1991)
ZR550-B3 (Zephyr) (1992)
ZR550-B4 (Zephyr) (1993)
ZX550-A1 (GPz) (1984)
ZX550-A2 (GPz) (1985)
ZX550-A3 (GPz) (1986)
ZX600-A3 (Ninja 600) (1987)
ZX600-C1 (Ninja 600R) (1988)
ZX600-C2 (Ninja 600R) (1989)
ZX600-C3 (Ninja 600R) (1990)
ZX600-C4 (Ninja 600R) (1991)
ZX600-C5 (Ninja 600R) (1992)
ZX600-C6 (Ninja 600R) (1993)
ZX600-C7 (Ninja 600R) (1994)

[srsupertrap]

Try this one Steve...http://www.kawasaki.com/DefaultFrame...HOWVEHTABS%3d1

The Gpz550's had issues with crank/rod bearings failing. I'd stay the course with splitting the cases and inspecting the innards. Less risky than purchasing some unknown lump of a bottom end. You should be able to find that clutch basket piece for less than $25.

My earlier info linking that part to the 750 twin was wrong, I believe these are the models that shared that part with the

Thanks Ed . . . the advanced search you found is very helpful. I have found a cheap low mileage EBay EX500 clutch hub.

On Friday I borrowed my neighbor's RolAir 2 HP 125 psi air compressor. Bolted that long piece of metal to the good remaining clutch hub posts to secure it, then hit it with a Craftsman 1/2 impact wrench. Nothing, again and again. Operator error, Ah I turned up the dial knob to maximum but still nothing. I finally broke out the propane torch and heated the clutch hub nut for 10 minutes . . . and finally it decided to come loose. Had to do the same for the transmission secondary shaft nut.

[srsupertrap]

On Sunday I split the cases


As I mentioned in an earlier post, when I inspected the gear set I did not see the "broken tooth". The gear set is complete and looks Ok. I guess splitting the cases verifies that fact.

Below; My finger is next to he broken tooth I found in the oil pan . . . notable wider


I moved the broken tooth directly above the Crank Hy-Vo. The broken tooth measures .530" wide more in line with either the crankshaft or starter clutch gear teeth.



Long & short of it I don't find the missing gear tooth in the gear set, crankshaft or starter clutch assembly. Again that gear tooth appears to have come from the crankshaft or starter clutch assembly.



Here are several crankshaft bearing photos. I have not measured anything but they appear to "look" good. Ed mentioned crank/rod bearing failures. What needs to be checked or should I just replace these . . . remember this GPz has been a money pit.





The starter clutch assembly even looks good. The starter clutch rollers are in the same condition as the one shown here below.


That sheared bolt came out easy. What else should I check?

[harley10]

Boy you have had some ****ty luck with this , but I bet when done it will be worth it. , don't give up, Brian

[Nessism]

Hi Steve,

Use plastigauge to check the crank bearings. If everything is in spec, no reason not to reuse them.

That broken tooth is a bit perplexing. Clearly it's not from the trans, so I think your assumption of crank or starter clutch is a good one. Maybe it's from the starter clutch that the PO replace replaced some time back?

[gearhead13]

Thanks Ed . . . the advanced search you found is very helpful. I have found a cheap low mileage EBay EX500 clutch hub.

On Friday I borrowed my neighbor's RolAir 2 HP 125 psi air compressor. Bolted that long piece of metal to the good remaining clutch hub posts to secure it, then hit it with a Craftsman 1/2 impact wrench. Nothing, again and again. Operator error, Ah I turned up the dial knob to maximum but still nothing. I finally broke out the propane torch and heated the clutch hub nut for 10 minutes . . . and finally it decided to come loose. Had to do the same for the transmission secondary shaft nut.

I broke a clutch basket that way, sucks.
I have tried air tools with my air compressor and doesn't work very well. Shop air has the pressure and AIR FLOW at high pressures to make them work properly.
Then I found this electric impact on sale for 1/2 price, has 350 ft/lbs. I love it its awesome Even removed my red loctited rotor off my big end 1100E crank, no problem

http://www.canadiantire.ca/en/pdp/mastercraft-maximum-impact-wrench-0541264p.html#.Uwpz3IWouZ0

[koolaid_kid]

Hi Steve,

Use plastigauge to check the crank bearings. If everything is in spec, no reason not to reuse them.

That broken tooth is a bit perplexing. Clearly it's not from the trans, so I think your assumption of crank or starter clutch is a good one. Maybe it's from the starter clutch that the PO replace replaced some time back?

I agree with using plastigauge.
Rings and bearings are about all you have left to check.

[srsupertrap]

I agree with using plastigauge.
Rings and bearings are about all you have left to check.

I will plastigauge the crank bearings and report back with results vs. GPz550 specs. BTW where should I measure the squeeshed bearing plastigauge? In several places, at the bottom of the concave or just find the lowest reading?

The crankbearing surfaces look "good". Some have stated I should replace the GPz big end rod bearings while I am in there. I have been told #3 would show wear first. BTW, I did not win the lottery. . . I already have a stretched cam chain to replace, broken cam chain guide & all the gaskets to make it tight.

Tom Kleeme http://www.klemmeperformancemotorcycle.com/ who is redoing the GPz head said he wouldn't touch those. Thing is I still don't know what failed and resulted in parking the bike for 26 years.

I will open this discussion up to other seasoned engine builders which of course does not include me.

[tkent02]

You still haven't found where the extra gear tooth came from?

[srsupertrap]

Here is what I did Sunday, I inspected the crank bearings with Plastigage SPR-1. Did it very carefully, took my time, torqued to spec (18 Ft-Lbs) and confident I have good results. The service limit is .10mm



From left to right






All of the crank journal bearings consistently measure .076mm which is safely under the service limit. None of the bearings are flaking. Those readings are acceptable. I will probably use Brad Penn green oil to prolong its life when I button it up.


Next, what does the crank journal diameter measure? My crank has "no markings" & the standard measures 31.984 to 31.992mm. The service limit is 31.96mm. Since I am using a digital caliper I lock the adjusting wheel at 31.98mm and see if I have an interference fit. The 31.98mm fits over all the journal bearings. I drop the measurement on the digital caliper to 31.97mm and it's a tight interference fit on every crank bearing . . . which means its good.



I believe this photo accounts for the PO stating this engine was "blueprinted" . . . check out #3 pork chops



I will be checking the connecting rod end bearing with Plastigage after work this week. It does not appear a crankshaft failure parked this GPz550 some 27 years ago. Still a mystery

[srsupertrap]

Poked around a little tonight to see if I could determine were the broken tooth came from.Have to look close because I inserted the tooth in the gears . . . Too small to be a crankshaft gear tooth



And the starter clutch (not wide enough)



But the best fit is here in #6. I can only guess but it looks like they replaced the gear set.

[Nessism]

Good sleuthing Steve. Must have been that trans gear then.

Bearings looking good.

Figured out the rings situation yet?

[tkent02]

Replaced the gear and missed a tooth. I wonder where it was hiding, or maybe they didn't even look. Congrats on finding it. Any more issues pop up?

You want to powdercoat those cases while you have it apart? I'm going to be home for quite a while.