Engine Gasket Question 1990 F12

[Mypoorfudge]

Hi folks,

As a few had seen my introduction post, I have and FJ12 needing a new head gasket.

I actually have the gasket already. See the pics below.




The engine was running fine except for a small leak in the head gasket and does not need major surgery.

My question now is - As I have removed the head, do I also need to remove the cylinder block and replace the gasket underneath that.

[FJ_Hooligan]

Not unless it's leaking.

You will need a new cam chain tensioner gasket and you should also replace the oil galley rubber seals between the head and cylinder and maybe new copper washers on the 2 right head studs.  I've gotten by with sanding the old ones down and reusing them.

[Mypoorfudge]

Thanks David,

Rubber seals definitely, and tensioner gasket def as well.

Will probably anneal the copper washers.

[Mypoorfudge]

Is anyone familiar with that head gasket above.

It was given to me with the bike when I bought it.

[FJ_Hooligan]

Cometic is a good brand name

[fj1289]

Is anyone familiar with that head gasket above.

It was given to me with the bike when I bought it.

That's a good gasket - Cometic MLS (multi-layer steel). 

What was the cause of the original head gasket issue?

[aviationfred]

I am not sure if it is an issue.... But in the top photo the displacement size of 1195-1202cc's. The OEM displacement is 1188cc's. Could this cause a problem with a good seal around the pistons?


Fred

[Mypoorfudge]

Is anyone familiar with that head gasket above.

It was given to me with the bike when I bought it.

That's a good gasket - Cometic MLS (multi-layer steel). 

What was the cause of the original head gasket issue?

I have no idea FJ1289, two days before I was due to pick up the bike the previous owner noticed a tiny leak of oil from the right hand side. He is a friend of mine and made me aware of it. He had probably got the gasket from Ebay after that and gave it to me with the bike. I rode thae bike for two years and only ever noticed the issue after high speed runs.

Fred, in all the times I looked at that Gasket, I never noticed the CC was not correct. Well spotted.

Maybe I can get another opinion on that issue.

[Mypoorfudge]

So is there anyone else out there that can advise on this gasket ?

Not sure if I should buy an new gasket or not 

[Pat Conlon]

Since you already have the head off, how does the new gasket look compared to the old gasket?
How does it look laying on the head?

If in doubt, I would just order a new Yamaha oem gasket and call it a day.
Rather than softening up the old copper washers, I would just get new ones.....although if you do develop a oil leak with the old copper washers, the fix is easy.

That's my $.02

[racerrad8]

So is there anyone else out there that can advise on this gasket ?

Not sure if I should buy an new gasket or not  

No: DO NOT use it.

Back in the late 90's early 2000's we had a bunch of problems with Cometic gaskets. They had issues with the coatings and they would burn out.

Since that happened back then we only use the O.E. Yamaha head gaskets.

Also, the oil leak should be coming from these Head Dowel Seals.

You will also need a timing chain Tensioner Gasket and possibly a Valve Cover Gasket and Valve Cover Bolt Seal.

Plus, looking at the photo, it appears the coating might be scratched.

Randy - RPM

[Mypoorfudge]

Thanks Randy,

I think thats fairy concise and accurate advice.

Im preparing a list .......