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Discussion Starter · #1 ·
I was just wondering if anybody has checked the squish clearance on there f7. And what it was and also what your compression was at that clearance. Thanks in advance! Btw mine appears to be about .060 and 120 psi
 

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It's the distance between the edge of the piston crown and head at TDC and has apparently become the new buzz word and clearance to check. For a stock engine it is a waste of time IMO...as most stock engines are most likely going to be .060 or more. If you plan on cutting your head down then this is something you would need to pay attention to.
 

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i know the low end spec is .059" and i think the high end spec is around .079". someone may correct me on that. sounds like you should be good at .060", but I wouldn't shave the head down any.
 

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.060 is good. Compression readings widely vary from one gauge to another. Your gauge reads 120 but a different gauge could read 140 etc... As long as the cylinders are within 5% of each other then you are good.
 

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Discussion Starter · #6 ·
It was a near new snap on gauge I borrowed form a mechanic. I've used it many times I trust it. Then why is my compression only 120 if its at the tighter clearance. People regularly report psi numbers for f7 between 130 and 150. I would think with that clearance mine should be higher. And I'm looking into this to decide if a rebuild is needed and I was thinking of doing the bmp head mod. Maybe my rings are just wore out. The old beast has 6400 miles
 

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with my snap on gauge, BMP head decked .020 thou ( .056 squish) my F7 is only 145 psi. I think alot of other brand gauges read higher. MY sled with the stock head and .077 squish was 110PSI.

On my ollld 02 polaris edge. The snap on gauge read 75psi and every hole. I had 3 exact same sleds, all edge 600's, all had 75psi. Which i thought was low.. When i sold the sled, a guy came with his own Compression gauge ( mastercraft i think?) it read 120psi, and he was happy as hell.
 

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Discussion Starter · #8 ·
I understand what your saying, it probly isn't accurate down to the exact pound, but we have used it many many times and its never given any readings that seemed out of the ordinary. I'm sure its not perfect but its probly in the right ball park.
 

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For what it's worth...my F7 from the time it was broke in to when it had 2k miles when I traded it pushed 125 PSI on a snap on guage. Honestly who cares what everyone else is running...most people lie, don't know or don't know how to properly check their compressions. For a stock engine 120 is fine as long as both cylinders are with in 5 lbs of each other.
 

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Discussion Starter · #10 ·
I am aware that 120 is fine. The reason I started this thread was because I'm looking into doing a top end rebuild and some small mods...one of them being head work or a possible billet head and a lot of people claim psi numbers of 140 to 150 with these sleds so I'm asking people what they get for psi and trying to find out how much the head mod or head will raise in addition to a rebuild. Come to find out that the varying from one sled to another comes mainly from the difference in squish, just trying to establish a good baseline if information on a subject that I'm new to before I tare my engine down and spend money in places where it won't make a difference. I'm trying to get as much out of it while staying reliable and near stock as I can. Just trying to do some research before I order parts that I know nothing about other then what a magazine says...and learn a little more about my sled in the process. Which is unfortunately where a lot of people go wrong...
 
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