1170 cometic headgasket

[pluto]

I have just finished rebuilding a gpz1100 unitrac motor, Debbens have done me a rebuilt head, crank and 1170 bore along with facing the head and block. It is now in my bike and running very sweetly indeed. Only issue is it is leaking oil at the head gasket, it remained oil tight for 5 whole miles! This is not something I'm unused to but I thought I had the procedure sorted - cam tunnel filled with rtv and left to dry, then a little sealant around the end studs and a little more around the cam tunnel, bolt it all up, re- torque after 1 heat cycle and off you go. I have used the fibrous looking single piece Cometic gasket with metal rings around the bore holes, the dowels have been shortened to allow for the skimming. My question is this, has any one used the multi layer steel (MLS) Cometic gasket with any success? I have one ready to fit - are there any special tips, do they leak as badly, do you still use a little silicone around the oil ways, do I need HD studs and higher torque settings? My zxr750 has one as a kawasaki genuine part which has been a fit and forget item (so far) and I would really like the same for the Gpz.
Thanks in advance
Dave

[Ginger Bear]

Dave, since your head and block have been 'faced' check that the cylinder head nuts are not bottoming out on the studs. If they are a set of APE nuts will sort you out. Sadly, once that gasket has started leaking it's unlikely you'll stop it.

I've always found these guy's great for cometic head gaskets at the best price, especially if you buy more than one!

http://www.performanceunlimited.co.uk/

[ZedHead]

I have a gasket if needed. On offer £37.99 + £6 shipping

[Al]

You did well Dave mine were lasting less than that.
Sorry not used MLS but thought i'd soldier on with the one piece fibre ones from Cometic; As GB said, all but two of my head studs have extra washers on them because they were bottoming out in the nuts.
I put machine washers in the oil way counterbores in the top face of the barrels with a teeny tiny bit of RTV on the underside. Chamfer side up to make a sort of matrix seal with the gasket pressing down into it.

a-250x250.jpg (16.08 KiB) Viewed 4458 times

Standard torque is 29 ft/lbs and i have been using 39 ft/ lbs for a good number of years with no penalty!
Thats with standard skinny 'waisted' studs and the short standard nuts.

I dont put any RTV on the face of the gasket at all but like you fill the cam tunnel hole to overflowing (just) and leave to set overnight.
Not had any issues at all with this routine now but did have many before.
Where's it leaking from??????

AL

[pluto]

Thanks for the help - GB I am going to pop an extra washer on each stud when I do the next re-torque and take some measurements of how much stud protudes so at least i will know if that is the issue.
Zedhead - which cometic gasket are you selling for that price - sounds very reasonable, if it is the MLS one have you had any feedback from previous sales?
Al - Hi, it's coming out both ends and a smidge in the middle just for good measure. The unitrac barrels are not countersunk around the studs so I was hopeful that my tried and tested method would be ok. I torqued the head down to 35ft/lbs, My current plan is to ride the thing as it is for 500 miles to run in the bores then check the shims etc, pop the head off and fit the MLS gasket and see what happens - they cant be any more porous than the fibre ones surely!

[ZedHead]

Zedhead - which cometic gasket are you selling for that price - sounds very reasonable, if it is the MLS one have you had any feedback from previous sales?

It is C8017 no reported issues.

[pluto]

Well just over a year has passed and I finally have an oil tight motor! I thought I should update the thread with my new found knowledge! I fitted the multilayer steel gasket with silicone in the cam tunnel as before, this time however before fitting the gasket I didnt just clean the mating surfaces I gently scrubbed them with very fine nylon scoring pad and brake cleaner until they were totally oil and grease free then fitted the head without touching the gasket faces. The MLS gasket has a rubbery coating that sticks to the mating surfaces to seal the joint. I then bought a new Norbar torgue wrench to make sure it was correctly tightened - I went with 35ft lbs on standard studs. Debbens gave me some start up tips for a fresh motor - 5 mins running then switch off, leave til the next day and same again. I did this for four days rechecking the head torque when the engine was totally cold. My first very short rip up the road revealed the gasket to be sealed but there was a leak from the cam chain tensioner and oil cooler where I hadnt changed the seals, that was easily sorted. The next trip out looked disasterous - oil everywhere - I had ridden much furter and the engine was much warmer so I feared the worst - tank off and it became apparant the oil was coming from the rear of the cam cover but above the gasket line - I had a spare cam cover in the garage so swapped it over and cleaned all the oil off. End of problem! The cam cover I think has a small crack in it that was opening up when hot allowing oil to escape - it ran down the back of the engine and covered the area on both sides around the head gasket joint. I did 20 miles this morning and no oil escaped. Long may it continue.

[chrisNI]

Always nice to see a problem solved. Nothing worse than oil where it shouldn’t be, outside the engine

[Big Fluff]

I've used msl gaskets without any problems. I always coat the gasket with loctite red spray. Never any leaks.