800
New member
The problem with the Wiescos is they are forged pistons, and they are softer than stock pieces, a forged pistons has more clearance because they grow more, they are softer and the skirts collapse. While some people will tell you they use forged pistons and let their motor heat up good before using may be true, however, if you're talking about a 97 and newer twin, how long does it really take to heat soak the motor before you stomp it? It has no thermostat so you would have to run it for what 5 to 10 min. on a cold day before you engage the clutch? Nobody does that. And while you're warming it up for that period of time the pistons are just rocking around in there scrubbing the skirts off.
Last time we were up, my buddy has a 800 Viper, he has a digital water temp gauge on it. When we started the motor it read -18, it took 7 1/2 min for it to get to 80 deg. because he has no thermostat in it, just some food for thought.
Because of the inherent problems with the 600 twin the only correct piston to use is the Yamaha service piston, the 8CR, with the AO at the end of the part number, while other parts may be cheaper, they're not gonna last as long.
Last time we were up, my buddy has a 800 Viper, he has a digital water temp gauge on it. When we started the motor it read -18, it took 7 1/2 min for it to get to 80 deg. because he has no thermostat in it, just some food for thought.
Because of the inherent problems with the 600 twin the only correct piston to use is the Yamaha service piston, the 8CR, with the AO at the end of the part number, while other parts may be cheaper, they're not gonna last as long.