waseem bhai, hosakta hay valve clearance ki setting sahi na ho, aap OHV valve box ko kholain, wahan 2 rocker arms lage hain, iski setting feeler guage se hoti hay , local mechanic bina guage ke setting karte hain, aap usko tight karoge to compression kam hoga, rocker arms main thora gap do ge( lose karoge) to compression bharega.
agar valve setting sahi hay aur phir bhi masla hay to camshaft ki timing sahi nahi hogi.
i am not mechanic i might be all wrong,
cya.