That's bad you would think it would run like a bag of poo an not make it off the drive on that jet. years back people use to come to me with there GPZ's as I had a rep as a know all on them thing was running popping an banging with a nasty rattle he said it had been like it all week on his 10 mile round trip to work I pulled the head off to find it was only running on 3 as that was all I could find piston wise the 4th was just not there just the rod an g pin what had almost worn its way front an back through the barrels the piston was in the oil which looked a bit like silver paint when I pulled the sump plug. he said it did not sound that bad till he was a mile or two from my place.