1983 240wr squish

[Eddie Lou]

Can anybody tell me what the squish should be on a 1983 240 wr (with a 250 liner fitted)?

Thanks

 

[suprize]

bugger all difference I think....should be an expert on this topic along soon... look at the parts manual...is the head a different part 240 to 250?

 

[Bigbill]

What's different between a 240cc and a 250cc engine? Does the head have a larger cc combustion chamber?

 

[PEZBerq]

240 standard bore piston 68.75mm piston. 250 standard bore piston 69.50mm. The first oversize piston turns the 240 into a 250. Air cooled engine head part numbers are identical for 240 and 250.

 

[Bigbill]

Thanks for explaining that. Do you pay the tax on the 240 when it's bored to a 250?

 

[Bigbill]

Back to the op. Playing with the squish ups the compression? Since it's a higher compression does it run better? Where do you get the different size base gaskets? Do you leave room for the rod expansion from the heat?

 

[jimspac]

Thinner squish band gives higher compression, thicker will yield lower compression.

 

[husqyhamm]

With new rod, bearings, smallend and gudgeon minimum safe squish 1,2mm.
New husky base gasket measures 1,2mm and when torqued down will compress to about 1mm.

 

[stormer254]

Use some solder placed between piston and squish area of head , turn engine over and measure result to get an accurate measurement of the squish. Keep squish as tight as you dare as it helps prevent detonation and adjust compression by removing or adding metal to or from the domed part of the head.
And read 2 stroke engine performance tuning 1973 by Gordon Jennings

 

[Eddie Lou]

With new rod, bearings, smallend and gudgeon minimum safe squish 1,2mm.
New husky base gasket measures 1,2mm and when torqued down will compress to about 1mm.

Thanks

 

[Eddie Lou]

Use some solder placed between piston and squish area of head , turn engine over and measure result to get an accurate measurement of the squish. Keep squish as tight as you dare as it helps prevent detonation and adjust compression by removing or adding metal to or from the domed part of the head.
And read 2 stroke engine performance tuning 1973 by Gordon Jennings

Thanks for the post, how di you add metal to the head? Would it be better to use a thicker base gasket?