TOPIC:

This is just a bitch session, I just need to ventilate my frustrations. Till now this bike was an incredible ride.

My Z1R has just clocked 215,000kms of hard riding 80% of its life. After a short stint at 150kph I felt a small vibration (normally my bike is very smooth) the more I rode, it got worse creating a backfire when idling. My initial thought was bent valves/ bad timing but I couldn't work out how this happened as the last drag was 100kms prior. So I assumed the carbies were blocked in some way.
I got home at a slow gutless speed (I'm sure I had a Vespa behind me honking to get off the road), did a leak down test and found 3 inlets leaking air. I pulled the head off and found on top dead centre the two pistons were not at even heights BUGGER.- twisted crank.
Luckily I have a spare Z900 crank with low kilometers that will now be welded and fitted. The valves turned out to be ok.

Bozo, was that a welded crank that twisted?

FYI.......I had my MKII crank checked by John Pearson during rebuild of Kawacide, one journals was 40 thousands off. He explained to me that many big center or 16 tooth cranks were off leaving the factory. He wasn't surprised to find my issue, which really surprised me as you would hope that production quality would be better.

Looks like quality control went down hill after the 70's.
Steve

My crankshaft has never been touched since new, so no it wasn't welded, it was only removed for new cam chain.
4TheKZ1000, I'll make sure the Z900 crank I'll put into it will be checked prior the welding, I do think Kawasaki had QC issues on these bikes BUT they still went on and on.
Swest, if you seen what I did to this bike when I was young, it was criminal. I guess I always knew twisting was possible especially when you consider she level pegs with an FZ1 to 160kph, it has surprised a lot of riders expecting the old Z to be left behind by any of the new naked bikes.
My mistake not getting the crank welded and balanced when I had it out for the new pistons etc.

What year is your bike? 15 tooth or 16? The 900 crank is lighter thus quicker REV's but they made changes to watch out for.
Steve

Wow, 215 000 km since 1977, I guess you don't feel too 'cheated' by kawasaki.

Did you bore the motor out for oversize pistons? I was told for a road GPz11 on 1170cc, that crank welding isn't really neccessary.

I think the heavier cranks are favoured by drag racers as they have more inertia for launching off the line.

Tyrell Corp wrote: Wow, 215 000 km since 1977, I guess you don't feel too 'cheated' by kawasaki.

Did you bore the motor out for oversize pistons? I was told for a road GPz11 on 1170cc, that crank welding isn't really neccessary.

I think the heavier cranks are favoured by drag racers as they have more inertia for launching off the line.

Your right I don't feel cheated, I was just venting. The bike has 1075 MTC pistons with speedway cams, 36mm ZRX CV's, mild porting, J model valves, so I thought all would be ok with the crank. I didn't miss gears so that was not an issue, and I had a rev limiter set at 10Krpm.

The crank I am getting welded turns out to be a Z1 which apparently had a small weakness in the crank centre but me slowing down I don't think this will be a problem.

MY QUESTION, apart from the keyway, is the Z1 crank taper for the alternator rotor the same as my KZ1000 1978 Mk1 Z1R??? I suspect it is but any confirmation would help, I also assume they all had 15T centre before the Mk11 came out.

Up to the Z1R D1 all the cranks had 15t centre pins and the same alt taper.
There is no weakness in the earlier cranks.
They all share the exact same components, rods and bearings with the larger webs being the only major difference on the 1000 cranks.
We run a welded Z1 crank in the Orient Express Turbo car tyre drag bike and it handles over 230 horsepower with no problem.

zed1015, you're a bloody champion, thankyou for your knowledge. I have to admit not that long ago (an hour ago) I managed to find an answer which was written by you previously relating to the difference in carnks.

Tyrell Corp wrote: Wow, 215 000 km since 1977, I guess you don't feel too 'cheated' by kawasaki.

For the record and for us yanks, this would be about 134000 miles. Quite impressive.

Shabba wrote:

Tyrell Corp wrote: Wow, 215 000 km since 1977, I guess you don't feel too 'cheated' by kawasaki.

For the record and for us yanks, this would be about 134000 miles. Quite impressive.

Babied Kaw's won't last that long

Daveo, you are right, I have noticed that slightly thrashed Z's seem to last and go better.

My three brothers rod early Z9's and they experienced the same thing, the engines love hard use. My other friends that rode their bikes "easy" ended up with slow engines, worse economy etc.