I havn't ever attempted to fix a blown HG before because honestly, I have never ran acoss 1 before until now.The atv is a peace 125cc. How hard is it?
remove 4 bolts on front and it comes off?

 

Not quite that simple.. The cam/crank needs to be put at TDC (top dead center) so you can remove the cam sprocket, then the cam, and then the head will come off.. there are 2 TDC's on a 4 stroke.. you want the one after the intake valve closes. Wire the chain to something so it doesnt fall into the engine.. when/if it does it can be fished out with a piece of wire. You need to remove the side cover so you can see the timing marks on the flywheel..

 

I just replaced one today. Like mywifesquad says, it's not quite as simple as removing the four acorn nuts on top. I searched it on YouTube-125cc head gasket replace and watched the vid. A little wrench smarts doesn't hurt either though. To remove the cylinder head, you need to remove the cam chain from the sprocket too. I put it all back together and turned it over, ugh,, nothing. Then I realized I'd timed it 180 degrees off. I slipped the sprocket around and it fired right up. I did advance it one tooth and it's really crisper in throttle response too.