How to check for a blown head gasket (nrg liquid cooled mc3 dd)

just wondering if someone knows a proper way to know if the head gasket is gone on a nrg mc3 dd liquid cooled (ps its a stage 6 streetrace i put on it like a year ago)

also a while back i remember going to set his spark plug gap with a feeler gauge (guessing guage was old)

what feeler guage is ment to be bought these days
cheers all
ps is spark plug gap ment to be changed for the streetrace?
or kept the same gap as for the standard head/cylinder

 

If no outward signs of fluid leakage, then compression tester is required. Screw into sparkplug hole, crank engine for about 5 seconds, read gauge. Good compression should be upwards of 90psi.
If it is losing water, either into the cylinder or exhaust it will blow white smoke.
Most plug gaps are 0.030" to 0.040" or three quarters to one millimeter in new money.

 

thought it was something like this
honestly ma8 ive rebuilt a few peds in past
just older now and mind is clouded due to alot of strressful events currrently going though
i havnt got a compression tester
any other method of test? or is this the only way?
thanks

when you say crank engine (you mean key to off and kickstart a few time right?)
thanks ma8

ps ped is a nrg mc3 dd (old school look)
he has a 70cc streetrace
a small peloni open air filter (im thinking to put stock filter back on)
mallossi reeds (unsure which ones as was on when bought ped)
polini variator (also on when bought ped)
polini belt (again on when bought him ped)
leo vince chrome exhaust (on when bought ped slight dent though)
and the standard 17.5 dellorto carb

what jet do you recon should be in this?