head gasket exchange / pressure relief valve?

[RalfR]

The head gasket is leaking after running a few minutes on idle.
Self healing or praying is no option so I decide to exchange the head gasket.
It looks like a straight forward operation and it is.  Remove the water, loosen the head screws and the head steady and then the cylinder head is coming free.
The old gasket was very fragile and has some fractures.... a new one was needed.
I designed a CAD drawing taking the measurement from the cylinderhead. This data is usefull for lasercutting.
As material I choose for aluminium. The benefit is that you can torque it down to final values and there is no need to retorque after the first ride. I applied a silicon based sealant from Elring which can withstand a temperature of 310 °C..... three times more than you have to expect from a hot engine.
Next time I will cut the sealant apply nozzle as small as possible, you need only a very small volume on both sides of the head gasket.
Now I have to wait 24 h for the sealant to dry out. Then I can refill the water and start the engine for testing.

Is it correct that the water circuit has no pressure relief valve and is open? With a slight over pressure of 1,1 bar you will not have boiling water up to almost 110 °C. Could be a usefull reserve when standing in traffic jam. What is your opinion about that topic?





 
 

[hendred]

You are correct, there is no pressure relief valve. It is an open system relying on natural circulation.  I have never had a problem with the water boiling.  There have been cases of overheating with high concentrations of antifreeze.  

[RalfR]

OK, than it is installed as it should be without pressure in the cooling circuit.
Many years ago I owned a Zündapp KS175 which uses the same "thermosyphon" cooling system without water pump. This cooling circuit had a pressure relief valve at 1,1 bar and also no cooling problems.
If water starts to boil the heat transfer decreases significantly due to the steam bubbles.

I filled up the system with a mixture of 60% decarbonized water and 40% glykol liquid from my Volvo car for aluminum engines. This should work to -20°C which we have 1 day in 20 years or so. The viscosity is comparable to clear water....

Short update: The new head gasket is leak tight. Still waiting for improved wheater to make the first test ride.....

[Smokey_Paul]

Excellent news 👏

[Arthur Farrow]

do go careful with the silicone sealant. If it gets into the water jacket little worms of it will break off and impair the radiator function.

PS my Silk boiled the water when I had the Boyer unit "especially made for Silks" it was a bastard to start too. Not impressed. My Luminition unit is not nice so awaiting a Tri Spark

[RalfR]

Regaring silcone worms creeping through the cooling system you are absolute right. The sealant I use is very stable when dryed out and stays where it is even when pressed out.

But you need a thin layer on both sides of the gasket to close the roughness of the surfaces and get it leak tight.  I think that it works and next time I will be even more carefull when I apply the sealant.

Ignition failures should not occur nowadays. On other motorcycles I have already used Ignitech and Vape from Czech republic. Both work quite well and Vape can deliver a combination of ignition and alternator. The Vape ignition is working without battery and has a strong spark.  

Ignitech offers programmable ignitions, pickups, regulator etc. for a fair price
http://www.ignitech.cz/en/vyrobky

Vape offers alternator-ignition units. Lots of variation also for strokers.
http://www.powerdynamo.biz/eng/systems/lists/overview.php

No Silk application yet.

[Smokey_Paul]

I use a very thin film of Wurth sealant and find that works well with the copper gasket.

Also Electrex World system replacing the alternator with combined unit for ignition and power works with good results, only real issue could be lower charge potential against standard but ignition works really well.

I have loads of Tri Spark units at work so may have a look at that also.