Squish: What happens if my squish is larger than the 0.75 - 0.95 optimal range?

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yuckfoo

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What's the effect of having optimized squish or rather, what is the effect of not having optimized squish? Specifically, what if my squish is 1.50 mm? Is this optimum range for squish only about high speed? My squish was over 2.5 mm. I'm currently sanding the head on my way to the optimal range of 0.75 to 0.95 (according to the YouTuber "Two Stroke Ports" who does work for Don Butler, so yes I trust his opinion.) I understand that the right range will get better combustion but also higher heat. Will I notice the difference between 0.95 and 1.50 ??? I think I'm just tired of sanding this thing, it's taking forever. :LOL:
 
really the most optimum squish for power is around 0.6-0.7 (for our crappy machining tolerance anyway)

short answer, yes you will, the less squish the more compression and more bottom end (and some top end as well) since are gas is pretty good (ie higher octane) so you can go until it blows.

long and much more technical answer

start at page 45
 
mark20 said:
really the most optimum squish for power is around 0.6-0.7 (for our crappy machining tolerance anyway)

short answer, yes you will, the less squish the more compression and more bottom end (and some top end as well) since are gas is pretty good (ie higher octane) so you can go until it blows.
Click to expand...
So it's more about bottom end?

I think I just need a break from sanding. It's so slow going I think I was just looking for an excuse to stop. :LOL: I'm taking a break now and will pick it up again later.
 
yuckfoo said:
So it's more about bottom end?

I think I just need a break from sanding. It's so slow going I think I was just looking for an excuse to stop. :LOL: I'm taking a break now and will pick it up again later.
Click to expand...
yeah, if you want more top end it's gonna be more effective to re-gear and do some porting and maybe a pipe (if you want to spend the $$)


here's a vid on explaining it better
 
mark20 said:
yeah, if you want more top end it's gonna be more effective to re-gear and do some porting and maybe a pipe (if you want to spend the $$)


here's a vid on explaining it better
Click to expand...

Thanks.
 
A belt sander will take it off faster. It will keep it relatively flat if you hold it right. But never perfectly flat and level like you need it to be. Sanding on glass or a mirror to finish is what you got to use since its perfectly flat.
 
I've sanded the rise on the head down to 0.5 mm. I'm using a 0.5 mm copper gasket and I'm still not getting any squish on my 1.50 mm piece of solder. Is it unusual to have to sand the jug down as well? I seem to have about a 0.70 gap from the edge of the jug down to the side of the piston at TDC. Should I sand the jug instead of continuing to sand the head?
 
yuckfoo said:
I've sanded the rise on the head down to 0.5 mm. I'm using a 0.5 mm copper gasket and I'm still not getting any squish on my 1.50 mm piece of solder. Is it unusual to have to sand the jug down as well? I seem to have about a 0.70 gap from the edge of the jug down to the side of the piston at TDC. Should I sand the jug instead of continuing to sand the head?
Click to expand...
I sand the jug, not the head. Idk if your even supposed to sand the head unless it doesn't affect the inner shape. Sanding the jug is fine though.

If you move the piston to TDC (top dead center) and measer the depth of the edge with calipers, that's a good way to know how much to take off.
 
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