Time to get my Honda motor ready for the upcoming racing season. The head is with Mr. Rieck for refurbishing. Seems my valves were trying to occupy the same space at the same time and all needed replaced.
Going with a different cam and Suzuki ignition with rev limiter to try and prevent it from occurring again. Hoping with more accurate timing and air filters the damage to the head and pistons can be prevented this season. Split the cases, here are some pictures. This is the first time the rods have been off the crankshaft since I built the motor 2 seasons/10 races ago. Checked the crank and rod bearings and all are around .002" clearance. Still new to four stroke engines so I asked a friend who has been racing since the 70’s to take a look. He believes the rod bearings were too tight. That explains the dark mottled color. Also sees metal in the crank bearings. Good news no damage to the crank is apparent. Measured the rod journals and based on the chart in the Honda manual I was one to two sizes too small! I think when I built the motor I replaced the old bearings with the same size new ones. Not sure I measured at the time. Think I got lucky not to spin a bearing or sieze one.
Here are a couple pictures:
Over view of the crankshaft bearings
Close up of upper crank bearing
Close up of lower crank bearing
Close up of rod bearing
Lower case with Plastigage on bearings, .002 clearance. Standard value is .00079 to .00181, service limit is .0031.
Rods with Plastigage on bearings, .002 clearance. Standard value also .00079 to .00181, service limit is .0031.
Also measured the rod side clearance and found three were .004+ and one was .007+. Standard value is .0047 to .0106, service limit is .0138. So well within the standard value.