550 cylinder liner height / head gaskets

[mdp]

after an 10 month lay up i started my 550 and ran for about 5 minutes, drained the engine oil, which looked like mayonnaise
bike will have been put away on fresh oil and i don't remember any water in the old oil when i changed it before i put it away

i had previously suspected that a head gasket had failed due to the bike pushing some coolant out when running hard

the head gaskets show no obvious signs of failure, (standard size) base o-rings look good

engine number is 04758 and has black sealant

i have measured the liner height and they are exactly flush with the casings, the thinnest feeler gauge i have is 0.0015" and i can't get it in anywhere under a good steel rule

heads were lapped on a granite block last time they were off, no sealant used

does a head gasket seem like the obvious choice of failure or should i think about re-sealing the cases?

i have read previously about amauri using shims? amauri, or cal are these available (i'm in uk)

i think flush liners are within spec, but a couple of thou above is preferred?

bike is track only, run mainly on large tracks at full throttle a lot, last use was two days on a very hot track day (about 35° - 40+°c) if memory serves i put new pistons in it before that event so its probably done about 4-5 hard hours

thanks in advance, any help appreciated

[Yascher]

you can try to pull out liners and grind a bit of the cylinder, which is good for making sure these are flat as well, however requires a lot of thinking what could be the downsides.....

[blacksaleen95]

I recommend making sure the liner height without the o-ring is .002-.003. Also be sure to check the flatness of the head surface as well as the deck.

We've had 3 separate sxv550's on our FSAE team(UNCC) and have had our fair share of sealing issues in the past couple years with them. The machine work from the factory on the mating surfaces on these engines is sub-par at best. We actually worked with Cometic and had case half gaskets made for these engines. I can tell you with the correct liner height, and the case half gasket, it has resolved the coolant leak issues. The prototype gasket we used was .010in, .005in was machined off each case half surface to makeup for the thickness of the gasket. I believe though, that .020 would be the optimal thickness as the cases need a good .01in off each side to get them flat. I think I have some pictures of the cases blued and then machined with a light cut, and you'd be amazed with how bad the cases are.

[Yascher]

please post some pics, this is valuable info!!!

[blacksaleen95]

please post some pics, this is valuable info!!!

Here ya go..

Older style halves cut..


Newer style...


It's tough to see, but in both pics there's some bluing after the flycutter has made a pass, showing where some of the low spots are on the cases we had.

Gaskets from Cometic. Can't thank them enough for all the help we've got from them. Great product and tech.








The heads and surface of the sleeves were surfaced with 400 grit on a surface plate. The heads had low spots, the sleeves were really good, I doubt .001 was even taken off of them. We used pressure sensitive film BEFORE we shimmed the sleeves for .002 protrusion with o-ring out. As you can see the deck surface is horrible and needs to be surfaced. We've been running the engine for about 8 months of testing and dyno time and have had 0 issues with the cooling system or head gasket. We did NOT deck the surface of the cases, and haven't had any issues. In the future we will likely make a cut on the deck as well to get the surface true. A couple things we did do was run a dab of a special type of RTV where the case halves meet up on the deck surface because of the added thickness of the gasket. I don't remember the name of the product, but I'll find out exactly what it was and post up. We also copper sprayed the cometics. In my dealings with MLS gaskets in other automotive forms, (Turbo fords, chevys) the copper helps if its not on a freshly machined surface.

We're not claiming that this is the end all and be all fix, we are just trying to share what worked well for us after a ton of bad luck with this engine. A lot of good information has been found on this forum, and we're just hoping to add to that.

[amauri]

If you disassemble and measure the mating surfaces of two crankcase halves that have been repeatedly heat cycled through normal use, they will always be uneven. No matter how perfect the machining operation was performed at the factory when the cases were new.

I applaud your efforts in re-machining the case halves and making special gaskets, but honestly not worth the effort.

Blown head gaskets on 2008 and newer 550 motors is caused by cylinder sleeves sitting flush with the deck, if they are flush they will fail when the bike is pushed hard. Simple as that.

It is well documented here on several old threads that the sleeves must protrude .002"-.003" above the deck, nothing new there. And of course, the three surfaces must all be perfectly flat and parallel to each other.

[blacksaleen95]

If you disassemble and measure the mating surfaces of two crankcase halves that have been repeatedly heat cycled through normal use, they will always be uneven. No matter how perfect the machining operation was performed at the factory when the cases were new.

I applaud your efforts in re-machining the case halves and making special gaskets, but honestly not worth the effort.

Blown head gaskets on 2008 and newer 550 motors is caused by cylinder sleeves sitting flush with the deck, if they are flush they will fail when the bike is pushed hard. Simple as that.

It is well documented here on several old threads that the sleeves must protrude .002"-.003" above the deck, nothing new there. And of course, the three surfaces must all be perfectly flat and parallel to each other.

Like I said, just trying to share our findings. The direction we took with the liners was largely due to what has been on the fourms. Simply wanted to let people know that there is an alternative to running sealant on the case halves.

[Micah / AF1 Racing]

I really like what you did with machining the case halves for use with a central gasket, I too found that even on 150 mile 07' motors the cases were so far from flat many were unusable due to massive differences in height around the sealing surfaces, no sealant works unless case halves are basically flat. You do not happen to be willing ti post cosmetic part number for gasket? I would like to try this with the next XV motor we do for the shop race bikes. We are having far more head gasket failures than we should on the two we race at .002-.003" protrusion and the heads are coming off not quite flat every time which is no doubt a factor. I do use sealant but only around outside edges of head gasket surfaces since due to protrusion issues do not get the same clamping force when the heads are torqued down. Use only a very small layer of sealant around areas where oil passages are located, any debris in the high pressure side can lead to disaster quickly.

[Targa Florio]

A very good post indeed, have you used a gasket 0.20 thick yet ? Out of interest, how many of your 550 engines failed due to deck hight, and how many failed due to the oil/coolant mixing at the case half's ?

[amauri]

I haven't had any engines mixing coolant in the motor since I started using Three Bond black sealant way back in 2007. My list of rebuilt motors is now up to 214 different serial numbers.

That froth in the oil issue is long behind us, the sealant is designed to take up any small gaps at the mating surface and it works perfectly.

We need to focus on the three head gasket sealing surfaces to prevent combustion pressure leaking into the cooling system, not small imperfections on the LH to RH crankcase mating surfaces.

[shwantz34]

I haven't had any engines mixing coolant in the motor since I started using Three Bond black sealant way back in 2007. My list of rebuilt motors is now up to 214 different serial numbers.

That froth in the oil issue is long behind us, the sealant is designed to take up any small gaps at the mating surface and it works perfectly.

We need to focus on the three head gasket sealing surfaces to prevent combustion pressure leaking into the cooling system, not small imperfections on the LH to RH crankcase mating surfaces.

Good morning Amauri

Do you still use shim under cylinder to obtain the right protrusion ?
If so where can i find them?
Do you sold them ?

[amauri]

Hello Schwantz,

I used the shims on a few motors many years ago and it was a good option at the time.
The problem is that making the shims to the exact size was expensive in the small quantities I needed.
At the time I had a sponsor that was able to Laser cut them for me at no charge.

I have not used the shims for a long time and don't have any more.

[shwantz34]

Hello Schwantz,

I used the shims on a few motors many years ago and it was a good option at the time.
The problem is that making the shims to the exact size was expensive in the small quantities I needed.
At the time I had a sponsor that was able to Laser cut them for me at no charge.

I have not used the shims for a long time and don't have any more.

Ok , so,what is the solution now if the cylinder set to low?
Machining the case? Its seems very complicated to do and
And probably very expensive ? Is it the only way to do it?

[shwantz34]

Ok , so,what is the solution now if the cylinder set to low?
Machining the case? Its seems very complicated to do and
And probably very expensive ? Is it the only way to do it?

Any sugestion ?

[S4R]

I made my own shims from 0.10mm stainless steel shim stock...

Mark out with compass and cut carefully...

Make sure you lap both the heads and the liners to get a good flat sealing surface...

I also used a 3mm cross section Oring in Viton...