KawasakiTrax Community
General Category => General Discussion => Topic started by: Kal k on February 20, 2017, 09:39:42 AM
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Hey I bought a 79 invader 440 a few weeks ago and am rebuilding the motor. I'm wondering what the stock squish should be on this sled. Can't find it anywhere.
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Squish?
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The distance between the piston and head when the piston is up all the way. It's a test they do at races to see if you have shaved heads.
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I'm not sure I've ever seen a Kawasaki spec for that? Tell us more.
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I think this is what Kal K is referring to.....
I don't recall seeing this published anywhere for the Invaders.
The most common measurement is the one shown on here as "squish band thickness at edge" and can be measured by sticking a piece of solder in the cylinder and cycling the piston up to TDC. Then you can measure the thickness of the solder after it has been mashed by the piston.
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Kal K, I have some solder at home, and a micrometer....I could check my 440 Invader after work today.
However... it has SPI pistons, not OEM (although they are typical "stock" replacements")....I used a Winderosa gasket kit during the last refresh of the engine in 2010...not OEM head gaskets....all of which could alter the exact thousandths of an inch when measuring the squish. :P
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When tuning for AAEN pipes they recommend taking 1mm off the surface of the head but the squish area should not be less than .075 inch.
Also, cylinder head volume of the 440 invader is 16.0cc +- 0.4cc
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Well, I tried the solder trick to find the squish clearance.
The electrical solder I had was so fine I had to wrap it to make it thick enough.
Apparently you are supposed to measure parallel with the wrist pin.
I tried a few times and keep getting 0.081 to 0.083".
Again, my engine does not have EXACTLY stock pistons or head gaskets, but it has to be pretty close.
The 2nd picture is a spare cylinder head showing where the solder lays when you stick the solder down through the spark plug hole. You need to bend the solder so it lays fairly flat, and make the bend long enough to reach right to the cylinder wall.
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When tuning for AAEN pipes they recommend taking 1mm off the surface of the head but the squish area should not be less than .075 inch.
Also, cylinder head volume of the 440 invader is 16.0cc +- 0.4cc
So, 1 millimeter equals 0.0394 inches.
If I shaved my cylinder heads by 1 mm, my squish clearance would be 0.082 (initial) -0.039 (1 mm) = 0.043 (final)....way too tight....I remember reading if you shave the heads, you need to re-machine the squish area also to maintain the proper clearance.
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True. The squish mus be tuned up to be no less than 0.75".
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When tuning for AAEN pipes they recommend taking 1mm off the surface of the head but the squish area should not be less than .075 inch.
Also, cylinder head volume of the 440 invader is 16.0cc +- 0.4cc
So, 1 millimeter equals 0.0394 inches.
If I shaved my cylinder heads by 1 mm, my squish clearance would be 0.082 (initial) -0.039 (1 mm) = 0.043 (final)....way too tight....I remember reading if you shave the heads, you need to re-machine the squish area also to maintain the proper clearance.
When I do the Invader heads only the dome is not cut.
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could the same effect be accomplished by leaving head surface and squish alone and building up the dome?
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398, when you cut the heads, what fuel is required?
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I run a set of heads that 398 shaved on my 81 Invader with excellent results. I use premium pump gas, which for me means 92 to 93 octane with ethanol.
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What do you mean by 398
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Interceptor398
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So what's the difference between the 398 and the invader heads? And how much did you shave them?
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Interceptor398 is a member on this forum. He cut my Invader heads for me.
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Haha ok now I'm getting what your saying. So do u know how much got shaved
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1mm of the face and squish area but none off the dome. Aaen trial spec.
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Question:Taking 1mm off the head just lowers the dome thus raising compression? The reason to take material off the squish is to prevent detonation? Couldn't the same effect be accomplished by leaving the surface and squish as is and building up material in the dome?
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Question:Taking 1mm off the head just lowers the dome thus raising compression? The reason to take material off the squish is to prevent detonation? Couldn't the same effect be accomplished by leaving the surface and squish as is and building up material in the dome?
"Squish is an effect in internal combustion engines which creates sudden turbulence of the fuel/air mixture as the piston approaches top dead centre (TDC). In an engine designed to use the squish effect, at top dead centre (TDC) the piston crown comes very close, (typically less than 1 mm), to the cylinder head."
Material is removed from the gasket surface, then the same amount of material is removed from the squish area. This keeps the squish distance the same. So yes, adding material to the dome would have the same effect. But it is easier to remove material from the gasket and squish areas than it is to add material to the dome.