800 ROTAX SEA-DOO The 785cc engine is one of the best, but it has a lot of performance room left. The head is in need of milling, together with re-cutting the squish band to optimize compression. Flame arresters finish the kit off. Result is a tons of low end, a hard hitting mid and very fast top end. A good aftermarket pipe also boosts performance, but requires a rev limiter.   Performance Note: The 800 is under aspirated.  In the past, engine-tech manufactured 42.5 mm butterflies to augment over-boring of the stock Mikunis, but no longer do.  We do not recommend boring the stock carbs without enlarging the butterfly.  Aftermarket carbs, although expensive, make a difference but usually require an external fuel pump.     Kit includes: Head mod: $100. Carb re-jetting and jet kit: $96. (includes cleaning carb filters) "Fly" Flame Arresters and adapters: $195. (all "Flys" come with Fly outerwears) (jet kit for just F/As are 80 pilot jets/stock 142.5 main jets/ 2.0 needle & seat with 3/4 turn out on both lows & 1/2 turn out on the MAG highs & 3/4 turn out on the PTO highs)  (warm/humid climates above 72F could require 75 pilots with an additioanl 1 half turn out on all adjusters) Total kit price: $395.