After my crash at Thunderhill in June 2002 on the FZR400 (see damage here), I had to do a lot of work to get the bike running again. The crash didn't damage the engine, but the head gasket did blow that weekend as well, so it was time for a rebuild. I gave the engine to G-Force Performance Center to get it done right this time. The cause of the blown head gasket was due to previous "creative" engine work, and I wanted to make sure everything was perfect after this rebuild.

The pictures below show some of the custom work G-Force did for me to fix the engine. The dowel work was because a previous owner had bored out the original dowel holes so they could shove the cylinder forward relative to the crank (creating a "better" crank to piston angle at TDC). This cylinder was my spare cylinder, so they either never used it, or they tried it and found that it was a bad idea. Mike Norman at G-Force discovered this issue after we had these cylinders bored and while he was assembling the engine. The old cylinders couldn't be used anymore and this was my only spare set of cylinders, so to solve it, Mike had inserts machined to re-position the dowels back in a stock location.

Originally, I thought I was blowing my head gasket because of the motor being high compression (Cosman pistons and a decked cylinder height). Mike suggested o-ringing the cylinders with copper wire as you see below. We confirmed later that the blown head gasket was because of exhaust valve to piston contact, but decided to do the o-ring anyway. It is probably overkill, but this engine shouldn't blow a head gasket ever again.

Mike had to do other creative fixes including the bushing for the shift shaft, doing a heli-coil on a striped cam cap bolt and re-marking the cam timing marks to make sure the cams are assembled correctly in the future. The aftermarket cams, and the misinterpreted markings were the reason for the piston to valve contact in the first place.

This engine has been raced for many years, and the multitude of mechanics and performance upgrades has taken its toll. I'm glad I entrusted Mike Norman to fix it. I'm a pretty meticulous guy and reasonably knowledgable about engines, but there's no way I could have fixed the engine and caught these issues as well as Mike did. He is one of the few people I know that is more meticulous than I, and he does it as a normal part of his job (including taking all the pictures you see here).

The engine has always run a total loss system. I asked Mike to take pictures of the flywheel replacement and pickup coil for future reference. Those pictures are also shown belown.

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(Click on the image for a larger version.)