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Did you check the rad for any hot spots? Hot plugs could cause pre ignition or knocking and an over heating cylinder would be a side effect of this. Try some 9 rated plugs.

That damage looks like something has clattered around the combustion chamber at some stage, but no damage to the piston suggests it's old damage.

Take the power valves off and get rid of the gasket. If you have a steel rule, stick it across the head and check it isn't warped slightly. If it isn't, get the damage welded and cleaned up on that damaged combustion chamber.

the minimum you should do with that head, is filing away the "sticking out" points on the damages.

they can become so hot they act as a spark plug causing to early combustion and detonation.

hi,

Thanks for the answers!

I checked everything with the laser termo after running.
The radiator is hotter on the inflow side, which is normal, otherwise no hotter point on it.

Will file the damage away, and try some 9'er plugs.

What else do you suggest?
It's still very bizzare it gets so hot, do you think it could only be the plugs??

Thanks
Mouser

have you tried to take of the sidecover and check the waterpump axle ( maybee the gear is broken inside)

the damage to the head is probably a broken pistonring in the past ( kawasaki made some faulty pistons in the beginning)

try to flush the cilinders and head maybee there's some rubbish in there.

i think that would be one of the last things to do because i woudn't know what it could be then if you checked everything else.

jarno

Hi @all

Luders wrote:........Hot plugs could cause pre ignition or knocking and an over heating cylinder would be a side effect of this. Try some 9 rated plugs.

9 rated plugs are Hot Plugs... 10 rated plugs are colder (NGK).
with 9 rated plugs you have a good chance for a hole in the Piston.....

@jan
i drove for years (in my TZR) with a similarly defective cylinder head without any problems.
so quickly nothing will happen


regards
Dirk

Yeah sorry, Dirk is right, the NGK scale is lower numbers hotter and higher cooler.

I suspect it's the head damage causing the problems.

Ben i don't think the pitting in the head is the problem

i have got some bikes with damaged heads like that and the don't give heating problems.

there must be a problem with the cooland canals , waterpump , cilinders , cilinderhead , rad, there not many other options.

maybee where missing something anybody other ideas.

I would put a steel rule across the head

@ Jarno and Dirk : there is damage and damage. as long as there are only some/even lot's of holes, that's not a problem.
but on this particular head, if you look at img 5860, at 1 o'clock at the end of th squish, that bit of aluminium sticking out might be a problem.

and I agree on actualy checking the gears for the waterpump : that it turns while kicking doesn't mean it's 100% ok.

Hello Jan

I think you mean the sharp edge (arrow)?
the gray patch looks like a hot spot?
can also deceive..



cheers
Dirk

Hi guys,

Many thanks for your efforts!

@Luders: What do you mean with putting a stell rule across the head? To see it's flat?

I will try to check the holes in cylinder and head. Seems not easy..

I will too try to check the gear of the water pump drive. Do I have to disassemble the gear box for that?

Thanks
Mouser

dirk wrote:Hello Jan

I think you mean the sharp edge (arrow)?
the gray patch looks like a hot spot?
can also deceive..



cheers
Dirk

off course I mean the arrow.

little pits don't matter much, it's the little things sticking out that can act as an ignition point.

@dirk and Jan,

To make it easier solving the question of the ignition point.

The right and the left cylinder and head had +/- the same temp. by measuring it after riding.

still better to file it away

and no, you do not have to take out the gear box, only the complete right engine cover.

I'll file it away and have a good look at the water pump drive!

Thanks
Mouser