Look for carbon plugging in the exhaust. The earlier model blocks may not have the Bung for staking the stator in place you will need to look at that. Stay away from the non thermostat models. I personally would start with tearing yours down first before anything.
Forget about trying to get the compression up the motor needs to come apart. After it is apart take Muriatic acid and clean the bore to see if the chrome is flaking off.
Because of Emissions the carbed motors are jetted extremely lean at an idle, that can cause the problem you are having. They are extremely easy to plug up, might be time for a carb cleaning. Or your idle is to low, Or something you have to live with
Here is the correct # for a chrome bore piston 39-17286A12 which supersedes to 39-827491A12. So I am going to buy a used Mercosil piston and compare them. If this is true I am thinking you should be able to use the WSM kit for the Mercosil motors to rebuild the older chrome bore motors.
This is the part # for a standard ring on a Mercosil Piston
39-827491A12
This is the # for my chrome bore piston. 0B238464 - 0G044026 (USA)
39-827491A12
And WSM also lists that ring part # for the Mercosil block that way. I also know that these are 12 packs
What the hell is wrong with you!!!! Now you insult owners of Yamahas because they may not have a lot of knowledge. IF and that is a big IF you were a professional you know that those are the people that keep the doors open at the dealerships. So why insult them and call them stupid? Why insult...
