Does anyone know the official squish setting?  I know Jim used to have a squish video on YouTube but alas, now it is gone.  I've searched and people throw out ranges but I'm just curious if anyone knows the official Gas Gas spec.

 

Thanks!

Doc

I would aim for around 1mm, but it also depens on your liking.

 

I think I normally use 0.8 gasket

Edited May 4, 201610 yr by crazybond700

On the motor before the Pro, the factory setting was not a measurement of the squish gap, rather setting the height of the cylinder such that the top was level with the top of the edge of the piston crown at TDC.

On the Pro motor, the rule of thumb for the base gasket sizing, to achieve the correct squish setting, was a 0.8mm thick base gasket for the 300, 0.5mm for the 250/280.

But, to be pedantic, would require checking the piston height as above rather than rely on the rule of thumb guide.

Hope this helps.

Bye, Peter B.

A piece of soldering tin in a loop will work fine to measure the squish. Just put it in the cilinder through the sparkplug gap, and let the engine turn a round.

Mr. Jim Snell was kind enough to give me the specs.  They are 1.25mm to 1.5mm for anyone else looking for them.  Thanks Jim!

Just for anyone whom might be searching in the future.... I bought a used '14 Gas Gas 250 TXT Pro Racing.   I had a heck of a time with knocking, pinging (pinking), stuttering, chugging and cutting out in the just off idle to 1/4 throttle range.   I jetted the carb every way imaginable (many different pilots, needles and even a #3 slide).  Going richer made it slightly better but not matter how rich I went I couldn't resolve it.  I also tried various types of fuel including race gas with no improvement. 

 

I checked my squish (piston to head clearance) and it was 0.7mm.  I changed the base gaskets to get it into that 1.25mm - 1.50mm range.  It runs great now with the stock jetting (45 pilot, JJH needle) although I still prefer the #3 slide over the stock #3.5.

 

Doc