Help 
i am trying to work out the compression ratio of my EX Mod 109 early 1980`s.
The spark plugs are the 8:1 type but had to set the timing at 6 BTDC to stop pinking at higher revs( no load), this is the 7:1 setting as far as i can tell.
The engine was running well but when checked before servicing( using strobe) the timing was seen to be well advanced I think this was down to a stuck mechanical advance, this was freed up (WD40) and the timing set static at TDC with the resultant pinking.
At present any info i gather just contradicts itself.
The head is the original leaded unit
Thanks
Greg
i am trying to work out the compression ratio of my EX Mod 109 early 1980`s.
The spark plugs are the 8:1 type but had to set the timing at 6 BTDC to stop pinking at higher revs( no load), this is the 7:1 setting as far as i can tell.
The engine was running well but when checked before servicing( using strobe) the timing was seen to be well advanced I think this was down to a stuck mechanical advance, this was freed up (WD40) and the timing set static at TDC with the resultant pinking.
At present any info i gather just contradicts itself.
The head is the original leaded unit
Thanks
Greg
