.21 OS outboard setup tips please!
- Thread starter JT1
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nitrotoys
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- Mar 10, 2003
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Are you setting up motor or boat?
you need to be alittle bit more clearer on what you want to set up on what.
Name the boat its going on and what you WANT in detail, you will get more help.
as far as OS OB, 3 turns out, add fuel and start.
you need to be alittle bit more clearer on what you want to set up on what.
Name the boat its going on and what you WANT in detail, you will get more help.
as far as OS OB, 3 turns out, add fuel and start.
Propjockey
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- Sep 16, 2002
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- 2,105
Nice combo...try Nitrotoys setting. What's your elevation?
Try setting the propshaft 1/4"-5/16" above the bottom of the rear sponsons and with neutral trim and about 4 oz. of lead on the nose , 2 oz. each sposon tip.
Use stick-on weights.
And see how she go's !! Get you a straight piece of 3/4" AC ply or Fiber board 30"x12" or so and cut a 4 1/2" slot in the center of the ply from one end . Slide the engine into the slot and press the rear of the boat down until both sponsons touch.
Then measure the distance from the center of the prop shaft to the board to get the 1/4-5/16". Also measure the trim at this time. You can measure the front and back of the prop shaft or the cavitation plate if it is straight use it. But check the prop shaft to make sure the trim measurement is correct, if so you can use the cav plate and a level or angle finder to set the trim .
Jerry Dulap "MR. TUNNEL" can give you better advice than I !!!!!!!!!
Use stick-on weights.
And see how she go's !! Get you a straight piece of 3/4" AC ply or Fiber board 30"x12" or so and cut a 4 1/2" slot in the center of the ply from one end . Slide the engine into the slot and press the rear of the boat down until both sponsons touch.
Then measure the distance from the center of the prop shaft to the board to get the 1/4-5/16". Also measure the trim at this time. You can measure the front and back of the prop shaft or the cavitation plate if it is straight use it. But check the prop shaft to make sure the trim measurement is correct, if so you can use the cav plate and a level or angle finder to set the trim .
Jerry Dulap "MR. TUNNEL" can give you better advice than I !!!!!!!!!
- Joined
- Oct 23, 2002
- Messages
- 6,451
I run a Mod OS and the X640 didnt go well with it so I dont think you will get the RPM needed from the OS with a stock muffler/ stock setup. Use a X437/3 ITs the best prop Ive found so far mod or stock, Ive tried about 20 different props, and the x437/3 is #1 and prather 215 is #2
The setup tips from WB is a good way to find out where you are. the O.S. does not like to run deep in the water, however 1/4 or 5/16 may be to high and you will get cavitation and not enough thrust, Alot depends on the boat, I would recommend running o degrees on pitch and start with the center of the prop shaft even with the bottom most edge of the tunnel. then move up a 1/16 at a time until It picks up "bad habits". when you play with the trim angle you may have to adjust the height again as the center line of the prop shaft will rise up or lower down depending on which way you go. Go in very small increments on both height and trim angle. I run 2 degrees positive on trim and centerline is 1/8 above the bottom of the sponson, with no weight (kinda rare).......... (this will be boat specific as to how much weight you should add if any). With my mod K&B /scratch built tunnel I have to add 3 oz. to the front.
Hope this helps ~ James
The setup tips from WB is a good way to find out where you are. the O.S. does not like to run deep in the water, however 1/4 or 5/16 may be to high and you will get cavitation and not enough thrust, Alot depends on the boat, I would recommend running o degrees on pitch and start with the center of the prop shaft even with the bottom most edge of the tunnel. then move up a 1/16 at a time until It picks up "bad habits". when you play with the trim angle you may have to adjust the height again as the center line of the prop shaft will rise up or lower down depending on which way you go. Go in very small increments on both height and trim angle. I run 2 degrees positive on trim and centerline is 1/8 above the bottom of the sponson, with no weight (kinda rare).......... (this will be boat specific as to how much weight you should add if any). With my mod K&B /scratch built tunnel I have to add 3 oz. to the front.
Hope this helps ~ James
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- Nov 6, 2002
- Messages
- 4,025
Aaaahhhhh, avoid the 65% nitro. That's extreme. 40-50% nitro is sufficent. Topfuel is right the 640 is too much. My Rossi w/pipe can't even push that or when it does is a bear to get up on plane. Go w/the 437 three blade or a X-440 two blade. Start out fat especially since the motors been disco'd and parts will soon be in large demand. Also, the motor should rest in a neutral position to begin with.
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- Apr 1, 2002
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- 4,073
The prop that works best for me with an O.S. Max 21 OB is the X440. A X640 is a bit much pitch.
W.B.'s suggestions are "Right On" and I don't have much else to add. I ran all the motors on my Hotshot Sprints 1/4" or more above the bottom of the sponsons. I run Wild Cat 65% with 2 oz./gallon of castor in all my 3.5 OBs.
If the hull is ABS, you might want to add a piece of 1/32" plywood sheeting 1" wide and the length of the sponsons along the inside edge. Then fill the gap with body putty and make a sharp edge for the bottom of the sponson. I like shape edges on my boats.
Jerry D.
W.B.'s suggestions are "Right On" and I don't have much else to add. I ran all the motors on my Hotshot Sprints 1/4" or more above the bottom of the sponsons. I run Wild Cat 65% with 2 oz./gallon of castor in all my 3.5 OBs.
If the hull is ABS, you might want to add a piece of 1/32" plywood sheeting 1" wide and the length of the sponsons along the inside edge. Then fill the gap with body putty and make a sharp edge for the bottom of the sponson. I like shape edges on my boats.
Jerry D.
