07-30-2012, 02:06 PM #1
- Join Date
- Jul 2012
Compression OK, Cylinder Walls OK, Burn Pattern OK
I'm at a loss as to what is wrong with my pro 785. I was out riding, and two of the front cylinder exhaust manifold bolts came loose. I was running WOT and it seemed to have lost power for a brief moment, but after I backed off it seemed like it was fine again. I babied it around for a little bit and it was running alright. It wasn't 100% but it was still running at maybe 90% or so.
I brought it in very shortly after that, only to find the two front piston spark plugs were white. My first thought was that there was an air leak or something considering those manifold bolts backed out, so I snugged everything else up. The head had proper torque, so did the cylinders. I also ran a compression test and everything is between 140lbs and 150lbs in each cylinder.
I talked to someone else who said that it might be a blown head gasket. I took the head off and looked at the gasket. There is a little area on the inside rim of the head gasket where the gasket is mis-colored and it looks like there's been some fuel and oil getting past it a little bit (which makes me think it might be burning water), it sounds a lot better dry running it for 5 seconds on land than it does in water. But, I showed it to someone else and they thought the gasket looked fine, and suggested it might be a broken skirt.
It definitely feels like it's running on all three cylinders. I cold seized it last year so I know how it runs on two cylinders, and it's definitely running on all three, not just two, let alone one. It feels like it's performing slightly better than an 1100 zxi from my experience, and it usually pulls harder than that. I checked the temps too when I got back in, and it felt hotter than it should have. It wasn't hot enough to burn me but it was enough to get my attention. I don't know if the temp sensor is broken or not, but that's also a possibility. I might have overheated it and got something stuck in the water inlet for the cooling system. The water is also pretty warm given the weather we've been having. If there's one thing I've learned it's that the Pro 785s are pretty sensitive to water temp when left stock.
Here are some pictures. Sorry if they are blurry, I am pretty sure the lens on my camera is greasy or dirty. http://imgur.com/yqMEt,xsuWI,w7SOJ,f...,vhXQM,yid3a#0
If anyone needs more pictures or anything let me know. I don't understand how the spark plugs are white yet cylinder walls look good and it still has good compression.
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