Squish and port timing..

[Thompo]

Hi folks

Putting a whole new top end on my mates 03 300. New pistion replated barrel of unknown year, exchange service.

Last top end on a 2t i done was a beta trials bike when i was 14 around 20 years ago lol. I was happy it worked and knew nothing of squish and port timing etc.

Roll on today and i want to do this right...
Ive fitted a single 0.5mm base gasket.
Pistion is around 1.0mm above the exhaust port at bdc.

Squish measures 1.8mm at cylinder wall increasing to 2.7mm, 12.5mm from cylinder wall.

Squish seems a bit large from my reading.

Reducing the base gasket to 0.3mm should help but will lower the exhaust port further.

Whats best compromise?

Hes new to offroad riding (in at the deep end on a 300 2t lol) so peak power isnt going to be an issue. Cutting the head isnt a option for a few months.

Cheers