So i have a 2005 450 EXC and the base gasket is leaking, i plan to change it out myself however there is two thicknesses of base gasket, 0.5mm and 0.8mm. From looking at parts fiches it appears that in 2005 they went from the 0.5 gasket to the 0.8 gasket, why is this? The top end was rebuilt just over 40 hours ago by Gibbs Performance and on the receipt it says that they have used a 0.5mm base gasket, could this be why it is leaking? The bike is a 54 plate so they could have thought it was a 2004 maybe?
