Optimum squish for a 12 300

[Diggs345]

Hi all

Iv have done a search and seen several figures mentioned , so whats the optimum measurement for the head mod , there is a guy local to me who will do it next week , off the top of his head he said 1.8 , iv seen anywhere from 1.2 to 2.0 mentioned on here , so can somebody please inform me of the optimum please.

Chris

[GMP]

Ron's have always come back around 1.2. Also, its about a COSISTANT 1.2mm clearance across the width of the band (matching piston dome). This is why the solder sample is important. He will also have to scoop the bowl out to readjust compression.

[Diggs345]

Originally Posted by GMP

Ron's have always come back around 1.2. Also, its about a COSISTANT 1.2mm clearance across the width of the band (matching piston dome). This is why the solder sample is important. He will also have to scoop the bowl out to readjust compression.

Thanks glenn , im taking him a solder sample too , he is a well known 2 stroke tuner in the uk , he makes handmade pipes for road race bikes too http://mickabbeytuning.co.uk/hydropipe.shtml
Thats quite an artform how he makes them

[Diggs345]

Glenn would that measurement alter any for the 300 , or for the octane rating or does it stay pretty much the same.

[Jakobi]

The octane rating is usually determined by the compression ratio Diggs. Super high compression requires better fuel. If you tell them you still want to be able to run on crap fuels when required and ask for a stock CR they will just remove more material from the bowl lowering the CR. I agree with Glenn too re squish height, 1.2mm is good.

[GMP]

Not sure what UK fuel is like, but Ron works with 200 PSI max for USA pump premium. My 250s measure 192 PSI. 300s are a bit less.

[Diggs345]

Our low grade fuel is 95 ron but where i can i run 98 or 99 ron , and thanks for the help guys

[Diggs345]

Just been swatting up , your super unleaded is much the same rating as ours take a point or so

[Jakobi]

Yeah the US uses a RON/MON rating I think where as we use a straight RON. I had my 250 set with an uncorrected compression ratio of 14:1 and have no issues running it on 98RON. I haven't tried it on 95 but have no doubt it would run fine.

On a 300 around 13:1 will favour bottom end while still letting the bike rev out.

[Vindicator]

Could the same squish or close be achived with the any of the S3 Stars Head insert ? Anyone knows ?