Hello everyone,

I bought a 2020 Gasgas GP 300cc, with the red cylinder head, but I don't have the right compression, there was 1.2mm of base gasket, does anyone know what thickness is the original base gasket?

Thank you very much in advance.
Olivier from Belgium.

I know that the 2023 model 300 is .3mm. I would assume it’d be the same then in 2020. Hope this helps.

Edited January 5, 20251 yr by RonH

Hi Ron, thank's for your answer, but I see that this documentation is for the new model 2023 with a new head. I try 0.65mm and this was all too much pressure, the motor dont turn right.

But thank's at all, it will be good to know for my next motorbike.

From memory they were 1 mm, but I'm not 100% sure. Can you measure your squish with your 0.65mm gasket fitted?

Edited January 6, 20251 yr by faussy

Ultimately, you want to use the base gasket (or gaskets) that gives a squish clearance compatible with your riding preferences, altitude, and local fuel.  This is done via experimentation.

As faussy mentioned, you should get a baseline by measuring your squish clearance. This link illustrates the procedure: https://www.vhm.nl/en/page/technical-support/squish-measurement   The "tin wire" is typically solder.

Hi Faussy, thank's for your answer, I always heard that a 1mm gasket was to have a smoother bike, but I'm looking for the origin.

I tried with the 0.65 joint, but it really doesn't work, I put the 0.8mm back. But what is the right squish?

Hi Konrad, thank's for your answer, I visit the link, and yes indeed, I did it before, I will done again and I come back. 

Have a nice day.

Notes I have on my old GG TXT321 say the minimum squish clearance is 1.25 mm.  Different thickness base gaskets are available partly to accommodate manufacturing tolerances, and partly for rider preference in power delivery (more squish clearance = softer).  

When you measure the squish clearance, make sure the head and piston are free of carbon.