Head gasket failure causes

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Professor
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Head gasket failure causes

Post by Professor » Tue Sep 25, 2018 9:53 am

I think different cylinder heights are likely to cause head gasket failure and creeping of base gaskets.

I've measured mine after having problems with the base gaskets slipping out and found heights were 0.35 different! I recently had one replated and the top of the cylinder was linished slightly convexly which made me think how accurately are they finished after replating. I've had the top of my barrels lapped flat and then I lightly skimmed the base where gasket sits then re measured height and used different thickness base gaskets to eaqual them up. I checked the optimum gaskets after bolting the barrels down to the cases and putting a straight edge across both barrels, you can measure any step in height with a feeler gauge.

Any time a cylinder is re plated it may easily be shortened slightly. I think the original cylinder measured 90.7mm high but will check, shortening in height will affect comp ratio, squish and eventually make the power valves tight against the head gasket

Head gaskets are now discontinued from Kawasaki! very useful of them!
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Re: Head gasket failure causes

Post by Gerrit » Thu Sep 27, 2018 10:22 am

All of the cylinders I have (both KR-1 and KR-1S) are 90.6 mm and I believe that is the standard height.

As for the head gasket, no doubt there are aftermarket gaskets available. One of the heads I have has grooves around the combustion chambers for an "O" ring which is a superior arrangement and I'll probably have the others converted as well.
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Re: Head gasket failure causes

Post by podman » Thu Sep 27, 2018 4:47 pm

I can remember an article in Performance Bikes from back in the day where they tuned a KR1 and said how poor the manufacturing tolerances where on the engine, noting the differing heights of the barrels and IIRC something around the KIPS valves sometimes being tight to move in their housings for similar reasons...

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Re: Head gasket failure causes

Post by Professor » Thu Sep 27, 2018 9:35 pm

An easy service to machine the heads to suit orings would be good :) much easier and cheaper to work on and long reusable lifespan of Viton orings.

Do you use an oring or two around the perimeter for the water / coolant jacket as well? this is more likely to need a cnc mill to machine an irregular groove. I guess it would be nice to cross section a scrap head to check how much metal there is to spare. What cross section diameter orings do you use Gerrit?

Sounds like some one has noticed the poor tolerances a long time ago then, so maybe not just a result from re plating.

Aftermarket head gaskets have a bad reputation for leaking coolant, although I've only used genuine so far.
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Re: Head gasket failure causes

Post by Professor » Thu Sep 27, 2018 9:48 pm

With the water jacket you would also need to seal the power valves and use copper or dowty washers to seal the head bolts, I can see why sealant is easier short term choice.

Any one with a scrap head spare?!
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Re: Head gasket failure causes

Post by Gerrit » Fri Sep 28, 2018 12:50 pm

The "O" ringed head I have has grooves for rings around the combustion chambers only, dimensions of the grooves are:
ID 60 mm, OD 65 mm, depth 1.7 mm so the "O" ring cross section is probably 2 mm. The head has also been skimmed significantly, about 2 mm, and new combustion chambers cut. The spark plug threads are shorter and suitable for 5/8" plugs rather than 3/4" reach, requiring copper spacers between head and 3/4" plugs. The two other heads I have are bog-standard.

I noticed BDK offer an "O" ring conversion for RGV heads, so perhaps they can also do this for KR heads.
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Re: Head gasket failure causes

Post by Gerrit » Fri Sep 28, 2018 1:02 pm

I have a 4DP TZ250 cylinder which has "O" rings around the combustion chamber and the perimiter; the head bolts (6 per cylinder) are sealed by gaskets according to the 4DP parts catalogue, part No. 90430-06616. I don't know whether these are Dowty seals or simple copper rings, though.
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Re: Head gasket failure causes

Post by 500bernie » Sun Jun 30, 2019 10:06 pm

Could the head gasket be replaced by a 0.6 mm thick laser cut copper gasket?
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Re: Head gasket failure causes

Post by Coose » Mon Jul 01, 2019 12:57 am

500bernie wrote:
Sun Jun 30, 2019 10:06 pm
Could the head gasket be replaced by a 0.6 mm thick laser cut copper gasket?
This came up in conversation today with my KR-1 chum. It would certainly be worth a try.

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Re: Head gasket failure causes

Post by 500bernie » Mon Jul 01, 2019 8:56 pm

I think I will have a look into it.
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Re: Head gasket failure causes

Post by KR-1R » Tue Jul 02, 2019 6:49 am

.
.

you could reuse copper gaskets on air cooled motors
BUT
youd prob need to rubberise them like the oem ones are coated.
BECAUSE
introduce a liquid and you might have a galvanic corrosion problem.

"When dissimilar metals are in contact with one another in the presence of an electrolyte, galvanic action occurs, resulting in the deterioration of the metal with the lower galvanic number. The electrolyte may be rain water running from one surface to another, or moisture from the air containing enough acid to cause it to act as an electrolyte.

Since copper has one of the highest galvanic numbers or nobility of the active metals, it will not be harmed by contact with any of them. It will, however, cause corrosion of the other metals if in direct contact. The solution is to prevent such direct contact with the use of separating materials, such as specific paints or gaskets."

a good gasket for your copper gasket might be a used KR gasket each side of the copper one - LOL

"Regardless of the method used to separate the metals, wash from copper surfaces should be prevented from draining onto exposed aluminum. Traces of copper salts in the wash may accelerate corrosion of the aluminum."

if you are going to complex program a KR head to be oringed you should just BUY Jans billet heads where the hard work has been done - an RGV head isnt complicated by KIPS valves - or reinvent the wheel again

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Re: Head gasket failure causes

Post by 500bernie » Tue Jul 02, 2019 11:22 pm

Hi Danny,
Every day is a school day 😍
So the black (ptfe) coating on the standard gasket is there to prevent galvanic corrosion between the steel gasket and the alloy barrel/head?
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Re: Head gasket failure causes

Post by KR-1R » Wed Jul 03, 2019 2:29 am

I fear given its been 30 years and even though 1000 head gaskets take up little to no space - remaining parts have probably been binned at Kawasaki Japan


I'm sure the coating on the OEM gasket is a sealant given the thinness of the sheet and non compressibility.

ever make a battery cell out of a potato and create current?
or the metals and electrolyte used to make your car/bike battery...

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"The metal higher in the galvanic series of metals, the “anode,” provides protection for the metal lower in the series, the “cathode.”
As can be seen from the galvanic series, zinc protects the lower-order steel."

As in zinc blocks are sacrificial protection for hulls of steel ships.
Also why Aluminium coatings are an alternative protection to traditional galvanizing of steel sheets such as the chassis components of your PC or the roof of your house.

The nobility difference/listed separation of Cu vs AL is why copper spouting or flashings are not friendly to aluminium joinery and something Architects need to be aware of.

Aluminium railings and fixtures used beside treated timber (decks/fences) which might have a high copper content

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som more trivia
The most electrically conductive element is silver, followed by copper and gold.
Silver also has the highest thermal conductivity of any element and the highest light reflectance.
Although it is the best conductor, copper and gold are used more often in electrical applications because copper is less expensive and gold has a much higher corrosion resistance (does not tarnish like silver)
which is why gold is default coating on audio connectors etc

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Re: Head gasket failure causes

Post by Coose » Wed Jul 03, 2019 7:07 am

Fair comments, I forgot about that....

Last night I sent an enquiry to Cradley to see why they're presently listing output shaft seals as being no longer available, where whilst I was on I asked about the possibility of sourcing the Vesrah pattern gasket set. It has to be better than what we have now...

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