Gilligan
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Tom I am surprised no one is jumping on that x-jet hull after seeing those videos.
a stock 800 66e motor is not real impressive in the hull. A well built lamey 62t will outperform it. A big bore 66e motor is a whole different animal, it will kill a lamey motor. Knowing what i know now, I would not mess with the conversion unless I was going big bore.Stock Port timing is not favorable for a freestyle setup with the stock 66e cylinders nor is the 120lb compression oem head.
Extra 10-15lb of motor is not as noticable handling wise, it just does much more damage to the hull when you land it upside or on it's side.
Pump is the heaviest factor right now in my ski. It is not as "twitchy" handling as most properly setup freestyle skis. My 148mm is around 30lbs. You can feel the extra weight. Back end does not want to slide around , hookup is more racer like. I can't get the nozzle to turn as far as the 144mm pumps because of design , the factory tilt rings, and my steering cable needs to be slightly longer to get quicker turns (pump is longer).
my whole ski is 280lbs. Very few freestyle boats weigh less than this and they have lighter motors and pumps. I know Jeff's hull like mine with the 5mm lamey, oem pump weighed 245lbs. . my wammer hull with 62t motor is 300lbs and it's lighter than the average freestyle ski. I'm convince i could get down to 260lb by changing my pump, Switching cylinders and head, lightening the crank and removing the water injection and some grinding on the outside of the motor. Pump would lose 15lbs alone
lightweight hulls handle differently, you have to lean them more than a superjet to get them to turn, the hulls ride much higher out of the water and are very boyant. They pop out of the water hard on landings. I noticed that on Jeff's hull and Steve's lightweight.de hull
Found this on groupK's website:
The cylinders on the GP 800 are unconventional by pwc standards. Instead of an aluminum cylinder with a thick iron sleeve, the aluminum cylinders of the GP8 have a thin layer of hard plating for the piston to reciprocate in. Yamaha calls this plating "Yamaha Ceramic Coating", but it’s basically "Nicasil" (a nickel-silica plating). This thin, but super tough, bore diameter has a much lower friction coefficient than iron, thus allowing for much quicker piston acceleration. This thin plating also makes for a much more conductive-friendly path for the heat of the piston to get to the water-jacket. The material of this plating is so tough that it can stand up to the forces of several piston scoring "episodes" with virtually no damage to the bore at all.
again......interesting :scratchchin: It is a well know mod but I did not know the 800 had it.
And if you big bore it, you put regular sleeves in, or if you get it ported you have to get it replated.
well, superjett said 'you put regular sleeves in', so i figured these were somehow different than the nikasil stuff i've worked with in the past. all my offroad bikes have been nikasil based, including my DR650 enduro.
a stock 800 66e motor is not real impressive in the hull. A well built lamey 62t will outperform it. A big bore 66e motor is a whole different animal, it will kill a lamey motor. Knowing what i know now, I would not mess with the conversion unless I was going big bore.Stock Port timing is not favorable for a freestyle setup with the stock 66e cylinders nor is the 120lb compression oem head.
fwiw, i tore into my yz250 motor because i felt it getting lower on power every passing weekend.. it never actually seized or failed mechanically in any way.. i just noticed i was coming up short on jumps i normally cleared, ..etc. turns out the rings wore away at the nikasil and i was getting blowby in the cylinder..
is there a way to know how 'thick' the nikasil plating is? .5mm? .25mm? just curious.