I have decided to swap out the engine on one of my minis. Both currently are running Briggs 35 hp with 1.7:1 reductions. Scott Holland and John O'Neill are putting together Rotax packages with gear boxes that will hopefully fill a nitch in our "pass-time". They are installing a Rotax 583 with a 3:1 gearbox and the new Whirlwind Razor X Core prop on mine. Scott has detuned this engine to around 85 hp and I am looking for a wot 45+/- mph. The hull is a super lightweight 12' Alumitech with a rear driver single and single passenger forward. The entire boat should weigh in just at about 500 lbs. This will give me a spare Briggs Vanguard 35 with under 40 hours and a 1 7/16" crank, an Arrow-prop reduction and three Warp Drive blades.

I will post pics when done (after filling my gator tags:-D).

Finally got this swap complete. Ended up having Rotax Rick in Naples do the final stuff to bring this motor to life. Ended up with 65-70 hp and a 3:1 gearbox with twin Bing carbs swinging a 70" 2 blade x-core Razor set at 16 degrees. Maiden voyage with my buddy in my Dixon Twister following went well. We ran a total of 7-8 miles through the day stopping to drown some dead shrimp from time to time. Burned just over one gallon of fuel. I kept it below 5000 rpms and will during breakin. The prop is set to max out at 6700 static. I still have not shot any pictures but will try to soon and post them on this thread. This was not a cheap project!!!

This was not a cheap project!!! HAHAHA!!! How very true! Rotax is PROUD of their stuff for what they charge!!! I'm finishing off my Rotax 532 swap, I just had to pay 75.00 for one little tiny exhaust ell! Can't wait to see those pics of yours too!!!!

Well, I learned that a b box 3:1 will not stay together on a 583 swinging a 70" whirlwind prop. Had to go with a c box 2.62:1 and adding a clutch this month. We will see how this holds up...

Was the b box just not robust enough? Idling problems? I'm thinking if going to a 3:1 on my boat.....love to see a pic of your set-up!

Bruce

Inspecting b box after failure, found straight cut prop gear missing 6 of the 57 teeth. All 19 crank gear teeth looked chewed on and spit out. The new c box has helical cut gears much heavier than the b box. Went with 2.62:1 to turn prop 2450 at engine at 6400. Adding clutch to reduce wear on crank at startup and idle. Pictures... Still working on project, then clean up, then pictures.