One of the power valves broke in half while Tony was racing. Vibration kept the broken parts in place while the engine was running. When the engine was turned off in the pit’s the lower half of the PV dropped down and kept the engine from turning over when I next tried to start it.
Rather than just replace the PV I took this opportunity to improve a few other things:
As you can see the exhaust ports have been cleaned up, they also now match the pipes. The 3 small bits in the foreground connect the two PV’s at the T, you can see between the cylinders. I made the small white sleeves to fit over the arms of the T to take up the space worn into the other half of the PV connector. Vibration kills these parts fast and that connector is expensive. My hope is that the sleeves will spread out the load and make everything last longer.
Yamaha stopped making PV’s for this model and none are left in stock. The V engine TZ 250 uses the same size PV just without a notch in the shaft. Two new V model PV’s and a little time with Tony’s Mill and, Prest-O Change-O, we have ‘90 PV’s. In this picture they have already been installed.
The other picture shows the case packing I did around the reed cages. This increases the primary compression and gives better throttle response. Note the rust on the cylinder studs. This bike really is 21 years old.
73 year old Tony will be back on board this month at WSMC and if you think these are the only improvments the bike is getting you and anyone racing Tony will find out the hard way.