Well mine did the very same thing and Tim repaired it and have had no problems. This bike will be seen at gilbert this year as it has for the past 4 years. Needless to say it can be fixed buddy!

yup, its a simple fix.... but I dont want it to happen again if I am the one causing the issue... LOL....im about to put a whole ton of power through this cyl...dont want any issues. Ill proably buy a new one and get this one fixed and use it as a spare at the track.

Dan the liquid in the gland will hydrolic the wall out, put the oring in there dry, if you do weld it install a greased piston in the bore and fill it with water and then weld it the plating will be perfect, if it needs plating millennium will fix the gland no problem

i would muchy rather fix the gland than a billet head bolt boss lol

Obviosly you have not seen my welding LOL, ill just send it to millenium as the cyl needs replate anyway from a lean sieze a while back...need the cyl to be like new for the turbo build.
Thanks everyone! You have a PM Tim.

If this is a "Cheetah" as in the powervalve style cylinder, Then that could be caused by running the domes Trinity sent you. If your not running domes cut by a good builder. (Note: anyone but Trinity) Than you will get detonation no matter what your timing of jetting. (squish is NEVER suposed to get tighter towards the center of the piston, or you'll send all that force out the O-ring!) Check it and see....

Trust me....been there done that.
Have Tim at Titan Racing cut you some domes. It will be the best money you ever spend on that motor. They are KNOW for having major issues on the 4 mill cheetahs, and on a few of the 10 mills depending on your cc's and fuel choice.

yup, the domes were negitive squish...I had to run race gas to keep it from detonating. On my other engines I built I had customs domes made..this engine is the first time taken apart... knew about the problem...did not use it much. You are correct! always check squish!!!

was it pushing your plugs out also?>

Hell ya... I took it out and herd the detonation... got off it.... one plug was loose..... retarded the piss out of the timing...still got detonation....put race gas is it and it was fine... put a few miles on it until I built a 441 cub and swapped out the engine....now im rebuilding this one... lots of folks warned about the PV motors having negitive squish... I did check the squish when building it... im like hmmm I dot like it but trinity says its fine....LOL... now I run much larger squish on all my engines... Tim from titan is making me some new domes.......nice helpful guy.... so are the other vendors here on the forum...

Dan, is the black material between the failed groove and the cylinder bore o-ring material? It looks like it to me. I am going to say the o-ring used was put in an o-ring groove that was just a little to small to accept it.
You may want to consider having an o-ring groove machined into the dome (maybe .010 deep) to make room for the o-ring to fit??

My saber did the same thing, its on its way to be welded right now and my dome's (all 3) will be getting o-ring grooved .010.