Generally the ‘race engines’ generally don’t come with manuals. The limits will come down to what the regulations of the class allow (in this case KZ). So basically you have to find out yourself what the best timing is. What the best piston clearance is. It’s a tuners class, so it’s up to you to find out really. You could speak to the US Vortex dealer. They should be able to give you same good baselines.
There’s homologation documents and stuff like that which might help.