bad head?

[YZ125rider21]

My friend started his car up lefted my house few miles down the road heard a really really loud pinging noise coming from the head i would believe so we took it off but cant seem to find anytrhing wrong on the top half....here is a description of what his car doing it would like take off really slow take a while to build up and then start pinging like crazy anytime you have the foot on gas....any ideas what it might be?....any help be nice thanks

[TheSilentChamber]

Check the timing. May be a tooth or two off and valves may be hitting the piston. Also what you you mean by top half? Like you took the valve cover off and looked at it?

[YZ125rider21]

ya i look at it from the valve cover and played with it a little bit make sure nothing was loose...i was told to drain the ill and look underneath to see if a bearing my have went out...i would think the timing but the timing being off wont cause the car to ping like drums hitting in a concert....

[TheSilentChamber]

I had a ford escort a few years back that jumped time and sounded like that, Anyone know if these heads are zero-clearance? (meaning if a valve opens when the piston is at TDC it will hit the piston)

[KoRnSaQ]

my friends timing belt snapped, and it bent some of his valves, if that helps any

[YZ125rider21]

nah timing belt still goodi gonna drain oild today and look underneath it make sure it not the bearings or anything...but i wondering if i should just get a head off a friend or something...cause the car redlines at like 5500 wondering i get a new head if that fix all the problems on this car...