Need help with new ski

[Speed_Freak_039A]

Hey guys. I just bought this ski. I need help with it.

http://www.x-h2o.com/threads/79575-Yamaha-Superjet-RN-R-amp-D-Pipe-MSD-UMI-Trim&highlight=

We took it out to the water and found out it has a blown head gasket. It was pissing water into the hull. The pistons says 0.50mm. The bore seems to measure 81.5mm

The ad says it has a MSD Twist head. I need to somehow figure out how to tell the compression so I know what octane gas to use. I also need to find out where to find a new head gasket and o-rings for it.

It also has the R&D Dry pipe. I need replacement o-rings and the pipe mount. I dont know if they had different versions of the pipe or not. Here is a pic of the head.

I guess the motor work has been done by HTR Racing in wisconsin. I have no idea if they are still around.

 

[Speed_Freak_039A]

OK guys. The motor has the 61x Case/Cyls.

It does appear to be a MSD Twist Head. I called and MSD didnt really know much about it. Been too long for them. They are checking into it for me. How do I find out what CC domes these are? Or if a stock head gasket will work with this? I need a head gasket and I seen metal ones, stock ones, blowsion has some. This is all new to me.

I cant find any info on HTR. By reading around sounds like they just port, polish, epoxy, sandblast the cases and such.

Could I just get a different head? I was reading with these cyls that after 10-20 hours the sleeves actually drop and cause sealing issues with the o-ring heads. Got that info from groupk. This it has .50mm over pistons I am thinking that HTR may have decked the cylinders. Not sure though. I basically need this gasket and to know what gas to run.

 

[Speed_Freak_039A]

Here is the head gasket that was used in it.

The thickness ranges from .022"- .030" or .58mm So Im guessing its a OEM .020 Gasket?

It is a soft plyable gasket. Not metal

 

[MNTURBO]

I'm not sure what your questions all are?

yes you could just get a new head, but that one should work just fine with a new head gasket.
ask in the WTB section for O rings etc

 

[Tyler Zane]

he just wants to know if anyone knows what gaskets/rings would work with this head and what cc's the domes are. and possibly a mount for the pipe.

 

[jaxrider]

From the pic it looks like you have 32cc domes

 

[Speed_Freak_039A]

Yeah. I was wondering what head gasket is required for this head. I ordered a OEM gasket. Should be here in a day or two. I am going to a local oring shop to get some viton orings.

So 32s maybe. What gas would be that be? 110? I also have a R&D Dry pipe which supposedly required the next higher gas. Ill try to get a compression reading once I put the head back on. Can I just go by the compression to figure the gas rating required? I thought porting increases the octane needed also. I only have 100 local. If I drive like 20 mins I have 110 also.

 

[Speed_Freak_039A]

I found the mount for the pipe. R&D still makes the parts.

 

[Speed_Freak_039A]

MSD is trying to find the book for the head. They barely remember this thing. lol

 

[Speed_Freak_039A]

Does anyone know if head orings are normally buna or viton?

 

[Big Kahuna]

I would think Viton. Get a compression guage and see what your cranking compression is, or you can measure the volume of the domes with liquid to see what you got.

 

[Speed_Freak_039A]

Ok. Ill try to get a compression reading

 

[SJBrit]

Be careful there - a compression pressure reading is not the final story on what octane gas to run. Mine runs over 200psi and uses pump gas - it depends a lot on the porting. Measure the dome volume and calculate the compression ratio based on volumes for the correct answer.

 

[Speed_Freak_039A]

Compression is 175.

 

[Speed_Freak_039A]

Be careful there - a compression pressure reading is not the final story on what octane gas to run. Mine runs over 200psi and uses pump gas - it depends a lot on the porting. Measure the dome volume and calculate the compression ratio based on volumes for the correct answer.

How do I do this?
I know it has been ported/polished. I cant find any info on the company that did it. I know when we picked it up it had race gas in it. The dude said he just used it to be safe. He only had it 3 weeks. So Im just about at a loss.

 

[Speed_Freak_039A]

From the pic it looks like you have 32cc domes

If that number is what that means then I would say yes. But I Have no idea.

 

[Speed_Freak_039A]

Would u guys say this is setup for CC racing more than freestyle? Thats what I am thinking. Is the R&D Dry pipe for a certain RPM range? Any ways I could make this more of a freestyle ski?