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4 stroke in a dumas

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4 stroke in a dumas

Old 08-25-2007, 06:37 PM
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Chickenheadz
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Default 4 stroke in a dumas

http://www.youtube.com/watch?v=1mQus8ix0qQ
vid of 4 stroke boat ^^
I've been sitting on an OS .48 4 stroke for a few years, and i jus got a 45" dumas hull thats never been set up. Im not looking to go superfast, atleast 30 mph though. propped accordingly, do you think this is a realistic possibilty?
I'm thinkin about goin clutchless, ima cut down a brass flywheel for it. The only real things i would have to spend money on are driveshaft and related parts, a 1/4 scale steering servo, fuel tanks, plywood to install stringers, and paint.
I hate seeing this junk lying around and i think it would be a fun build.
let me know what you guys think, if you have any input I'd like to hear it!
Old 08-25-2007, 07:42 PM
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BB Modss
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Default RE: 4 stroke in a dumas

iv played with some 4 strokes in boats, the hassle of building a water jacket for them out weighs anything, 2 strokes make more power.
Old 08-26-2007, 03:01 PM
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Chickenheadz
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Default RE: 4 stroke in a dumas

Ya, the water cooling is a slight issue, have to figure that out or just not water cool it.
power is a result of torque X rpm. 2 strokes might rev to 30,000, but they got crap for torque. and therefor have to run small 2 bladed props. Besides, I read somewhere that 16,000-21,000 rpm is most efficient in model boats. how about a 4 runnin 16,000 with an agressive 3 blade? with a flywheel, its got the torque to push it.
No, I absolutely will not go out of my way to buy a 2 stroke when i already have a hardly broken in engine begging for a home.
Only 2 stroke that would ever touch this boat is a gas engine... I've been searchin around, and The 49CC engines from racing pocketbikes seem pretty sick.
Old 08-26-2007, 08:08 PM
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Default RE: 4 stroke in a dumas

Not to be brash but the best 4 stroke i had would only turn 12,300..after that it just floated the valves, also the 4 stroke motors CC for CC don't stack well, you need a .52 4 stroke to equal the power and torque of a decent .21 and thats still pressing it, Don't let me sway you, Ill help where i can, i just don't want to see you get your hopes up and be let down! What motor do you have and ill go do the leg work on finding you a flywheel, the good news is most .50~.80 4 strokes have a very nice long crank with 1/4-28 threading..octura makes 1/4-28 collets for 3/16 cable



EDIT: You can't NOT water cool the motor, one time i did cut a prop down and make a fan shroud..it works OK but only OK..water is the best way...

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