Racing Kawasaki snowmobiles past and present > Kawasaki snowmobile racing, stock to full mod

Invader head mods

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Interceptor398:
I will soon be modifying a pair of invader heads.  We have the Aaen trail spec as a starting point but wish to go a step farther.  I will post a picture to help with the discussion soon.  045 squish is the happy spot for this adventure.  What say you??

gixxer6:
I have used the Aaen spec trail heads on several Invader motors over the years with great results.  They perform well with stock porting and the stock pipe.  They work very well with premium fuel (92 octane for me).  Cutting more off is a complicated thing, on a stock sled it doesn't make sense as you would need race fuel.  By the time you are ready to run race fuel you will have ported and piped the sled, both of these things will affect the compression ratio on a 2-stroke.  My .02 anyway...

Interceptor398:
This one will be for race fuel. The Aaen trail spec for the Invader is .032 off surface A and B to move the dome down to raise compression.  The goal is .075 of "squish" for the trail porting. In this case .045 is the squish goal for a race fuel motor.  Any thoughts and advice will be helpful!!

sprocket:
It all depends on what pistons & gaskets you use, some of the newer Wiseco Pistons have a different dome to them, they also have a different ring locations then the stock Invader pistons. Good rule of thumb is to degree your engine & measure everything before machining. Taking it off "A" will raise compression, "B" will decrease compression what's best ? Both do, if the pistons aren't stock. On "B" the angle will optimize the fuel better but if you machine too much off you will lose the cc area in volume.
Most cc in race form 17cc or less you will need to run a high octane race fuel to compensate the machining you done. That's why you see the interchangeable domes instead of machining it all out which sometimes can cause heat problems.
.075" squish is stock anything less than .045" is race.
Gaskets all range in thicknesses make sure you measure them

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