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Stock Squish

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Does anyone know what the squish should be I"ve read everything from .761 to 1.2mm ( .03 - .047 inches)

Right now mines at .94mm (.037 inches)

I'm going to mainly be riding track using pump gas. 2008 125sx

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From what I know, I would think your squish is good. Get too close and you will have to run race gas.

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From what I know, I would think your squish is good. Get too close and you will have to run race gas.

img3143h.jpg

I know, I had detonation before so I'm trying to get it right this time. On the last piston the previous owner had a .4mm cylinder gasket. I"m going to run a .4 + .25mm which puts x = 0 and gives me a little more squish.

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Stock squish is usually on the high side - about 1.6mm in my experience. Usually with a 0.75 base gasket. I generally set the squish to around 1.3 mm at near sea level to run pump gas. I feel this is conservative. Also, this is with a stock (uncut) head.

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Stock squish is usually on the high side - about 1.6mm in my experience. Usually with a 0.75 base gasket. I generally set the squish to around 1.3 mm at near sea level to run pump gas. I feel this is conservative. Also, this is with a stock (uncut) head.

Thats a little higher then what I've been able to dig up. Whats your typical compression with that much squish? From what I understand too much squish can also lead to detonation.

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Thats a little higher then what I've been able to dig up. Whats your typical compression with that much squish? From what I understand too much squish can also lead to detonation.

too little gap can lead to detonation. From talking with Mike at Cycle Playground 1mm is about as close as you want to keep running pump gas. My head had been cut before and was around 1.2mm. He lowered it to 1mm, with my X at 0. that is why I said you were close. I would add the other base gasket and give it a whirl.

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Thats a little higher then what I've been able to dig up. Whats your typical compression with that much squish? From what I understand too much squish can also lead to detonation.

I just noticed you are running a 125 sorry. Are asking what it's set at from the factory or what you can set it to safely (without detonation). If the latter I think 1mm is near the conservative cutoff. I believe the smaller diameter pistons run smaller squish values - certainly the chainsaw guys run below 1mm. Perhaps someone can dig up an equation.

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I'de like to know what they run squish at from the factory but also whats safe enough to run without increased risk of detonation or loosing hp on pump gas.

I think i'm going to stick with what I have for now .94mm (.037")

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