FH680v loosing power

[clutchrod934]

When i engage the PTO and starts cutting grass the blades slow down as if belt is slipping .I replaced belt and pto clutch and same thing.If the pto wasnt getting enough voltage would it slow down the blades? This Kawasaki engine is on a hustler Z model 926923.any help is appreciated. Oh and it has a brand new carburetor

 

[StarTech]

The FH680v is a v-twin. Most likely you have a cylinder down.