I need a new prop for the Honda 50 HP on my Mac 26X. Should I go to the Honda dealer or am I just as good going to Boater's World or other after market sources? Any recommendations on changing the pitch? Thanks all DaveDaniels
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Timm Miller
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dan
High Elevation Prop?
Yo.....26X Mountain Sailors ! Can someone help me with the right prop size conversion for 5000'to 6000' motoring? Right now at 5000'the 26X with a Honda 50 does 10-12mph at 4000rpm maxed out(with ballast). Should I be reaching higher rpm with a different prop? Mostly run at 4-5mph/1500-2000rpm. thx..dan
Yo.....26X Mountain Sailors ! Can someone help me with the right prop size conversion for 5000'to 6000' motoring? Right now at 5000'the 26X with a Honda 50 does 10-12mph at 4000rpm maxed out(with ballast). Should I be reaching higher rpm with a different prop? Mostly run at 4-5mph/1500-2000rpm. thx..dan
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Mike
High elevation???????
Sorry to jump in the middle here but Dan of Colorado Springs seems to have the wrong idea about elevation verses prop. Elevation has nothing to due with prop diameter and pitch. If performance falls off at high altitude, it is due to fuel/air ratios being messed up by the thinner air. If you have a carbourator fed engine, you need to re-jet it, if you have fuel injection your dealer may have a new control module for high altitude operation. Happy Sailing, Mike
Sorry to jump in the middle here but Dan of Colorado Springs seems to have the wrong idea about elevation verses prop. Elevation has nothing to due with prop diameter and pitch. If performance falls off at high altitude, it is due to fuel/air ratios being messed up by the thinner air. If you have a carbourator fed engine, you need to re-jet it, if you have fuel injection your dealer may have a new control module for high altitude operation. Happy Sailing, Mike
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dan
Wrongo !
Decreased pitch can "partially compensate" for decresed hp due to altitude. The decreased prop pitch allows the engine to reach max hp rpm. I am looking for the correct size to run at high elevation operation. Our friend from Calgary will know the answer. thx......dan
Decreased pitch can "partially compensate" for decresed hp due to altitude. The decreased prop pitch allows the engine to reach max hp rpm. I am looking for the correct size to run at high elevation operation. Our friend from Calgary will know the answer. thx......dan
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Mike
Compensation, not correction
The reason power drops off at higher altitudes is beacause the fuel air ratio changes. Fuel air ratio is critical to proper engine operation and long life of the motor. Too rich and you will end up with needless carbon deposits and possable plug fouling. Too lean and you can overheat, warp a valve or even burn a hole in the top of a piston. Changing props because the motor is Putting out less power due to an improper fuel air ratio is a stop gap measure. With less power the motor can't turn the prop as efficiently. Changing props does nothing to cure the underlying problem. Ask the outboard shops, they love to see people come in for these repairs. Mike
The reason power drops off at higher altitudes is beacause the fuel air ratio changes. Fuel air ratio is critical to proper engine operation and long life of the motor. Too rich and you will end up with needless carbon deposits and possable plug fouling. Too lean and you can overheat, warp a valve or even burn a hole in the top of a piston. Changing props because the motor is Putting out less power due to an improper fuel air ratio is a stop gap measure. With less power the motor can't turn the prop as efficiently. Changing props does nothing to cure the underlying problem. Ask the outboard shops, they love to see people come in for these repairs. Mike
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Doug Rodrigues
Elevation / high altitude...
Engine power will be lost because of lessened atmospheric pressure and too rich a mixture. A reciprocal engine will operate with a fuel/air mixture between 11:1 (rich) and 15:1 (lean). At high altitude, setting the optimum mixture will smooth the engine running, but not get back 100% power. At 5,000 feet elevation, the best that can be expected from a non-turbo charged engine is approximately 75% of sea level power with the optimum mixture setting. If outboards had an exhaust gas temperature sensor and a mixture control (as in airplane engines), maximum power for any altitude would be set with the exhaust temperature at 125 degrees C rich from peak exhaust temperature obtained from leaning. To make up for the loss of power, the engine RPM's would be increased to have more power cycles per minute which would equalize the difference in power loss from sea level. However, fixed pitch outboard props don't have such a fine tune where such a combination of engine and a perfect prop pitch can be obtained: the engine can overspeed and bend connecting rods if the prop pitch is too fine. Re-jetting an outboard for high altitude will have it running too lean (and hot) for sea level. That's when exhaust valves burn and pistons melt. So...just remember to change to sea level jets when returning to sea level or your engine can fry at high power settings above half throttle. As for a finer pitched prop, unless your engine has an overspeed cut-out to protect the engine, I don't think that changing props to experiment would be wise.
Engine power will be lost because of lessened atmospheric pressure and too rich a mixture. A reciprocal engine will operate with a fuel/air mixture between 11:1 (rich) and 15:1 (lean). At high altitude, setting the optimum mixture will smooth the engine running, but not get back 100% power. At 5,000 feet elevation, the best that can be expected from a non-turbo charged engine is approximately 75% of sea level power with the optimum mixture setting. If outboards had an exhaust gas temperature sensor and a mixture control (as in airplane engines), maximum power for any altitude would be set with the exhaust temperature at 125 degrees C rich from peak exhaust temperature obtained from leaning. To make up for the loss of power, the engine RPM's would be increased to have more power cycles per minute which would equalize the difference in power loss from sea level. However, fixed pitch outboard props don't have such a fine tune where such a combination of engine and a perfect prop pitch can be obtained: the engine can overspeed and bend connecting rods if the prop pitch is too fine. Re-jetting an outboard for high altitude will have it running too lean (and hot) for sea level. That's when exhaust valves burn and pistons melt. So...just remember to change to sea level jets when returning to sea level or your engine can fry at high power settings above half throttle. As for a finer pitched prop, unless your engine has an overspeed cut-out to protect the engine, I don't think that changing props to experiment would be wise.
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dan
Thank you Doug !
Being that I live at 6000'EL and plan to move to about 1000' soon, I will not do the change jets thing. Will run rich for now and be on the lookout for carbon buildup on the plugs. The Honda 50 does have over rev protection. Right now I peak out at 4000rpm/12k with ballast. Usually run at 1500-2000rpm/6k. Motor is rated to run at 5500rpm. Think I won't fool with it for now ! thanks again.......dan
Being that I live at 6000'EL and plan to move to about 1000' soon, I will not do the change jets thing. Will run rich for now and be on the lookout for carbon buildup on the plugs. The Honda 50 does have over rev protection. Right now I peak out at 4000rpm/12k with ballast. Usually run at 1500-2000rpm/6k. Motor is rated to run at 5500rpm. Think I won't fool with it for now ! thanks again.......dan
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Rick
Same Problem as Dan
Hi Dan, I'm having the same problem with my Honda 50 on a 26X. The motor is new but well past the break-in period. I've never been able to get more than 4200 rpm at full throttle with or without ballast. Help
Hi Dan, I'm having the same problem with my Honda 50 on a 26X. The motor is new but well past the break-in period. I've never been able to get more than 4200 rpm at full throttle with or without ballast. Help
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dan
Check with the Dealer
Hi Rick.... Check with your local(expensive) Honda shop. All of this elevation stuff is really site specific. Rejetting sets you up for problems if you want to go to the coast(Dougs article) Getting a prop with less pitch sets you up for overrev(which we have protection from?). I am going to do NOTHING for now and just cruise around slower! You need to take the mast off anyway, to get the speed to make any of this worthwhile. And I don't like piloting without ballast(to SQUIRRLEY!) happy motoring......dan
Hi Rick.... Check with your local(expensive) Honda shop. All of this elevation stuff is really site specific. Rejetting sets you up for problems if you want to go to the coast(Dougs article) Getting a prop with less pitch sets you up for overrev(which we have protection from?). I am going to do NOTHING for now and just cruise around slower! You need to take the mast off anyway, to get the speed to make any of this worthwhile. And I don't like piloting without ballast(to SQUIRRLEY!) happy motoring......dan
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dan
Yo Fred from Edmonton!
Hi Fred......... Can you help Rick and me on what prop you are using on the Honda 50 for high el motoring ? thx....dan
Hi Fred......... Can you help Rick and me on what prop you are using on the Honda 50 for high el motoring ? thx....dan
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