Need thicker base gasket 951di

[Shawn022]

I am looking for a thicker cylinder base gasket for a 951 DI. The engine is an SBT reman engine. I purchased a gasket kit from sbt to try and eliminate any issues.

The issue I am having is the gasket kit came with a five hole base gasket. The base gasket I removed from the engine has no holes for identification purposes but measures out to roughly .060”. 1.54mm
It actually has a metal core with gasket material on each side.
I am 100% sure SBT built this engine.
I need the thick gasket for proper squish. The readily available .8 mm gasket will not get me there.
Does anyone know where I can find the thicker gasket. Of course my first call was to SBT and they had no idea what I was talking about. They said they only had available the gasket that came in the kit.
Thank you very much

 

[mikidymac]

SBT only carries one gasket because they know it is thick and will not cause any running issues. It might make a tiny bit less power but will not detonate and blow up if the squish was too small. SBT is very well known to cut heads to lower compression and I can only assume to avoid warranty claims.

The thickest gasket you can buy is a 0.8mm even from seadoo so if you still don't have enough squish you will have to get the head domes cut and reshaped.

If your measurements are correct and the SBT gasket is actually 1.54mm then it is almost twice as thick as the largest one seadoo makes, so if you don't have enough squish even with that double thick gasket something is majorly wrong with your engine.

 

[Shawn022]

That is what I thought. I thought that they would only send out a thicker gasket to avoid problems. But the gasket that came in the kit was a five hole gasket.
0 .5mm. The gasket in their rebuild was over 1.5mm
The squish with the thicker gasket should be about .074”. I have call into sbts tech department. I talked to someone in Parts last time. Probably not the best idea.

 

[mikidymac]

Considering you said it is a composite gasket with a metal core it is ether a special gasket only their rebuild shop uses to correct defects or it is an actual spacer that someone made that uses regular gaskets on the outside. Either way, you have something really strange going on so keep us updated.

 

[Shawn022]

I wonder if the head was excessively machined and they used a thicker gasket to make up the difference?

 

[Shawn022]

Also why does Sea-Doo set their squish with the base gasket and not the head gasket? Thank you

 

[mikidymac]

I think it comes from the older engines as they used an o-ring head gasket and so there was nothing you could do on that end.
Also on the 951 you are only changing the thickness of a cheap paper gasket instead of trying to make a bunch of different expensive composite head gaskets.

 

[mikidymac]

I guess I should have asked first...
Why are you taking apart this SBT engine in the first place?

 

[Shawn022]

The reasoning makes sense but sure doesn’t make engine rebuilding easier.

 

[Shawn022]

The engine had an air compressor failure that cracked the case. I believe the bolt holding the air compressor rod to the balance shaft backed out. Very low hours but unfortunately out of warranty. So all parts are being re-assembled into another case. Had a different balance shaft rebuilt and welded by Dan Squires. He did a great job.

 

[Shawn022]

Finally got to talk to SBT tech today. They really didn’t know anything until I was on hold for a while. They must’ve been asking somebody that actually assembles engines.
Turns out that SBT does use custom-made gaskets in some of their rebuilds. They referred me to a company called gasket technology. That is who they use for their custom gaskets. Turns out that company is Cometic gaskets. A name that I have definitely heard of. And I already knew that if all else failed I could get a gasket from them.
I was able to easily order a .060 gasket with a metal core. The metal core is an option.
Susan with cometic gaskets was awesome. She got my order taken care of in under five minutes.
The only downside was that this gasket that I needed to reassemble my engine cost me $50 to my door.

 

[mikidymac]

I hate to bad mouth a company but SBT sure does some off the wall stuff.

 

[Mekanix]

They can machine anything and compensate with with either welding and remachning or in this case custom gasket.
From everything I have seen with sbt I don't think they intend for their engines to be repaired. Rather send it back and get another one. They can be creative but the average person needs some engineering and machining skills to work with stuff like this.

I wonder what your problem actually is?
Did they cut the head, the cylinder deck or base or, well the case is different so we can assume it's closser to stock.
Might be worth getting an exchange cylinder block and head from them for this one