06-24-2009, 05:59 PM #1
GPR DOWN! Need an online diagnosis and some parts :(
I've never seen a piston look like this. There's no signs of detonation around the edges of the piston or on the head... it's just a lil beat up from the scrap aluminum banging around in there so I'm trying to figure out what caused this.
I was riding 2up when this happened. I went out for a couple hour ride and the ski was runing great all day with a mix of glass water high speed passes and some rough open water riding. I was probably less than a 1/4 mile from the launch on my way back crusing 30-40mph and it was like someone flipped a switch and the exhaust tone changed and sounded boggy. I checked the plugs and the mag side was black and wet so I thought it was just fouled... obviously not. This was the first time riding 2 up on the ski and only the 2nd or 3rd time out running the Yam84 curve so I'm thinking that was my problem
It's 95 degrees in my garage right now and I'm sweating like a mofo! Apparently TCR likes to use lots of red locktite on everything and I can't find my 1/2" ratchet so I've had a real enjoyable day with my pos 3/8" craftsman ratchet and I can't seem to hold onto anything today eigther... so far there's a powervalve cover bolt, gasket, and 10mm socket under my motor right now
Ok I'm done now... I'm inside cooling off before I go back out to tear it down the rest of the way
06-24-2009, 06:04 PM #2
06-24-2009, 06:06 PM #3
06-24-2009, 06:09 PM #4
If anyone want's to know what's been done to the ski it's all here...
The rings are still there.. wouldn't they of broken off if they got hung up on the valve or port?
06-24-2009, 06:12 PM #5
06-24-2009, 06:52 PM #6
Since all of the damage originated at the exhaust port it has wondering what caused it. The ski is jetted fat on the low end... is it possible that excess fuel being burnt in the pipe caused this?
This is the first GPR motor I've worked on and the first thing that looked odd to me (besides my charred piston) was the height of the pistons... I took some measurements with a ruler just to give everyone a ballpark. The mag cylinder is at bdc approx 3" from the top of the cylinder, the middle cylinder is 3/4" from the top of the cylinder, and the PTO is 1-1/16" from the top... I talked to Steve (VOODOO) on the phone as I was pulling the head and he said that's the way these motors are... it just looks really weird to me
06-24-2009, 07:06 PM #7
looks like the ring jumped over the locater pin and spun around and hooked the exhaust port
see the nice imprint on the head and some on the top of the piston that looks like a small piece of ring?
06-24-2009, 07:20 PM #8
by the cleanliness of the head and the little blowout marks where the head gasket was i would say water ingestion and it blew the head gasket?just a thought?
06-24-2009, 07:26 PM #9
sorry saw your rag and spray cleaner in pic 7 and zoom in showed no blow by sorry wrong answer!
06-24-2009, 08:32 PM #10
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