MPI - Mountain Performance Inc.

MURDER YAMAHA

MURDER YAMAHA

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Oct 19, 2015
Messages
1,751
Age
50
Location
Minot ND
Does anyone know if they are still in business?
Google says yes, but been calling for days and no answer.

I understand they are the last ones that sold the Peak Performance Heads.
Need a replacement dome.
 

Here is what I currently have
they are stamped SRX
(2) are Y72224-100 22.5cc
(1) is Y72224B-100 22.4cc

I think one of my 22.5 cc heads are banged up if I recall correctly.
 
20220325_104224.jpg

Are your chambers like the left or right? Step into chamber squish band, or direct taper? I assume you have the step if you say they are stamped SRX.
 
Here is the only pic I had on my phone
 

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So here is where I am with your setup, I have 21cc SRX domes, but that really isn't the correct dome for your application. You really need to run the Viper domes if you are running a viper head gasket, or at least only a partial viper gasket. Your squish band is going to be too wide and could promote detonation. The srx domes have a 0.035"ish squish band and the viper gasket is round that I think, so you would be up in the 0.060 - 0.070". IMO that is to wide. That is one of the reasons I made my own domes, to play with that band. I have viper domes in the 22-23 range, I would just have to cc them as I do not have them marked. And that isn't happening today, I would need to go get a piece of plexi and trim it down to work. I do have some MPI viper chambers, I would just need to clean some aluminum off them. are aren't hammered up like yours is. I melted a handful of pistons on the exhaust port side and some deposits were left in the chamber. This was with some heavily ported and port raised jugs. Needed more compression, race gas, and my small chambers, but was trying to find a livable trail setup. Needless to say, I didn't.
 
Lol, been there, done that.
I would be interested in the viper mpi stuff, as of now, I have 130 psi on all 3.
 
Ok, riding is done for the season. I'll grab some plexi to Cc them when I'm at the store, but it won't be today or tomorrow.
 
Well the good news is I had a set of Viper 21cc domes that I cut a SRX squish ring into and those domes come out to 22.5cc. I would suggest those one and running 1 layer of the head gasket with copper spray on both sides. That would give you .048" quench which is in the good range and they would be interchangeable with your existing domes.
 
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