Hey my friend has his 98 mxz 670 at my house and I was riding it and it was running perfect. I parked it in my yard and today when I went to start I thought the recoil was broken somehow because I could just pull it out with my pinky. Then I looked under the hood and the spark plugs had a whole bunch of oil leaking out of where they screw into the head. So I took them off (they were tightened) and the whole thread was just black with oil. So I`m thinkin the reason why there is no resistance when I pull it is because theres no compression in the cylinders which = blown motor. How could of this happened? There was oil in the sled (obviously) I didn`t ride it hard at all..and when you blow an engine you cant keep riding it just bogs down..but the last time I rode it it ran perfect until I parked it! So I dont know what happened..unless it IS the recoil but I highly doubt it. How much does a 670 engine cost because I have a feeling im gonna be buying one..