1985 Kawasaki GPz750 needs refresh

[Nessism]

Oh bummer, sounds like rod knock and loud.

Hum. The 550's are known for rod knock, but not the 650/750. Are you sure? The clutch basket is known to develop lash, fix as shown in my build thread (installing new rubber cush bumpers). Also, the secondary shaft drive sprocket has rubber bushing that develop lash. Hope the problem isn't truly rod knock, because the fix for that involves splitting the cases.

 

[Buffalo Bill]

Yikes! Figured it meant splitting the case.
The sound is a really loud knock, and seems to be coming from #2 cylinder in the case.
I will have to open it up for a look see. With winter coming on my garage will be too cold to work, even with a heater.

The reason this bike looks in fine shape on the outside, must be because it never ran very well.

Another weird thing is there is a center detente in the steering race, like it was meant to help steer the bike straight ahead?? Really throws off my confidence in corners.
I already ordered replacement tapered roller bearings.

 

[Rob S.]

...With winter coming on my garage will be too cold to work, even with a heater.

That's a shame. But I happen to know that most Kawasakis come from the factory house broken. If you think she might have an accident, spread a few newspapers. And don't cry over spilled milk. :friendly_wink:

 

[Buffalo Bill]

I'm really growing to appreciate Suzuki motorcycles.

 

[rphillips]

That's why I's always liked roller bearings on crankshafts.

 

[Buffalo Bill]

After thinking about how the engine was behaving before I pushed it to just over 8,000RPM, then it lost power continuously until it quit, and now has a rod knock.
I think it had low oil pressure and was doomed to fail soon.
Where would I put an oil pressure gauge on this engine?
I ordered an ebay salvage oil pump, that the seller claimed to have taken apart and examined. He has a high rating.

 

[GS1150Pilot]

Z1 redline was 9k, and it made good power past that any day of the week.

The Sporty red line may have been 6k, but there was virtually never any benefit after 5k.

Wait, what were we talking about?

Max power on the Z1 came at 8500, Rob. Not much point to 9K there. The (gads) Shafty CB900C could run pretty much exactly the same times and speeds, and it actually made max power at 9K.

 

[Rob S.]

Max power on the Z1 came at 8500, Rob. Not much point to 9K there. The (gads) Shafty CB900C could run pretty much exactly the same times and speeds, and it actually made max power at 9K.

The Z1 and my 11EZ (and virtually all UJMs of the day) were identical in that respect. Max torque at 65k, max hp at 85k. But they still make good power past red line. Unlike my Sporty, which just sputtered and would not rev past 6k.

My 1971 Honda CB350 was interesting: 12k tachometer, red zone from 9 to 11k. The owner's manual said it could be run up to 9k indefinitely, and from 9 to 11k briefly. NEVER supposed to exceed 11k. Bulletproof.

 

[GS1150Pilot]

The Z1 and my 11EZ (and virtually all UJMs of the day) were identical in that respect. Max torque at 65k, max hp at 85k. But they still make good power past red line. Unlike my Sporty, which just sputtered and would not rev past 6k.

My 1971 Honda CB350 was interesting: 12k tachometer, red zone from 9 to 11k. The owner's manual said it could be run up to 9k indefinitely, and from 9 to 11k briefly. NEVER supposed to exceed 11k. Bulletproof.

The 1200 motor I have built for my Sportster revs to 7 but stops making good power at 6500. The stock bike has a limiter that can be tuned out.

 

[Buffalo Bill]

Just getting started with disassembling engine.
So far cams and valve clearances are all very good.