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Author Topic:   Yamaha 150 hp increase

taypow1 posted 08-21-2005 03:51 PM ET (US)
My 1992 19' Outrage ll is just not up to the job of pulling skiers with more than two people on board.
I keep the fuel on board down to thirty gallons but you still need to drag (seemingly forever) until the boat plans and you pop up.
Is there anything I can do besides decarbonizing the carbs to get more performance from the 150 hp Yammie?
Jock
SIM posted 08-21-2005 04:27 PM ET (US)
Jock,
What I have found to work very well for these applications is a product called Permatrim Foils. They are powdercoated aluminum plate foil that bolts to the cavitation plate on your lower unit. What they do in effect is when the engine is tilted down all the way, with them installed they increase the size of that plate therfore making the boats stern lift\rise at lower boat and engine speeds.
They work very well on outboard powered boats for pulling skiers, tubers ect. It lets your boat get on plane noticabley(sp) easier without nearly the bow lift you are now experiencing.
There are several other designs out there....do a google on Doel Fins ect.
Andy

SIM posted 08-21-2005 04:30 PM ET (US)
Jock,
one more thing.......what prop are you currently running?
Andy
macfam posted 08-21-2005 05:52 PM ET (US)
Jock,
Do you have a spare prop?
If not, It's time.
Get a prop that is 2" in pitch less than what you have.
For example: If you have a 19" pitch move top a 17"
Use the spare for you "power prop" for sking, and heavy loads.
It's not that difficult to change props.
You may find that the prop you have might be a bit too agressive for your boat. Does the current prop allow you to reach the higher end of your max rpm range? If not, it's too much prop.
Just be careful that when your using that prop with light loads and no skier that you don't over rev.
taypow1 posted 08-21-2005 06:36 PM ET (US)
I have a vensura prop with a 19" pitch the two stroke Yamaha is raised to the third hole and a doel fin has already been installed.
It's like the hull would do much better with a 175 hp or 200 hp motor to push the added weight of the upper deck added to the model in 1992.
I was hoping someone would know how to get more HP out of the 150 by changing the jets on the carbs or some other mods that would not require changing motors.
Jock
oroseiwhaler posted 08-22-2005 08:06 AM ET (US)
Hi taypow1,
i had 2 '98 Yamaha 150 carburetted Outboards on my '98 Outrage 23. This type of motor is very powerful and i think that it should tow skiers without any problem.
I immagine two problems:
1. Carburation problem, unscrew all spark plugs and check if they are all the same "dirty" If some is/are diferent than the others it means that that cylinder is firing bad.
2. Check fuel line if it's kinked, restricted, sucks air,etc.
3. If the spark plugs are heavy fouled (oily) have checked the oil pump.
4. Change all 12 spark plugs with new ones
5. Check your rpm on WOT. It has to bee 5000 to 5500 rpm with 3 persons and 30/40 gallons of fuel and safty/skiing gear.
If you reach only 5000 rpm, get a 17'' propeller and try again.
6. If the engine get's full rpm while starting towing, but the boat don't accellerate you may have to test a bigger 21'' propeller due that your 19'' vensura is slipping under the extra load from the skiier.
7. Try to move all weigt forward to the bow and trim the motor all way down, this will help the boat to plane quicker.

Keep us informed
Best regards
Chris
LHG posted 08-22-2005 02:27 PM ET (US)
Assuming the engine doesn't need work, you should be running the 17" Vensura, not 19". If water skiing is your MAIN concern, get a 5 bladed High Five in 17" pitch.
bsmotril posted 08-22-2005 03:32 PM ET (US)
One of the newer style elliptical cut slalom skies helps us old farts get on top quick from a deepwater start. BillS
taypow1 posted 08-22-2005 05:20 PM ET (US)
Larry,
Your exactly right I checked my prop and it is the 17" pitch Vensura.
I don't think the motor has ever been decarbonized and am looking for a mechanic to give it a profesional look see.
Bill,
How did you know I had one of those wide fat man skiis?
Does anyone know what the difference is between the 150,175 and the 200 HP Yammies?
Saturday I switched props with a 175 HP Yammie ski boat that a friend owns and it completely ran the hull out of the water when pulling up skiers.
His engine also has a much different sound than my 150 (throaty).
Jock
bsmotril posted 08-22-2005 05:42 PM ET (US)
This might be an ideal application for one of thoese Merc variable pitch shifting props. I don't know if they are still made, but I did read some good reviews about them in ski boat applications a few years back. I think they were made after Merc introduced the Flo-torque hub adapter system, so you should be able to match it to your Yammie. The upper and lower pitch limits are adjustable, and it is basically a two speed (dual pitch) prop that shifts at an rpm that can be adjuste by varying the springs that control the shift point. BillS

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Author	Topic: Yamaha 150 hp increase
taypow1	posted 08-21-2005 03:51 PM ET (US) My 1992 19' Outrage ll is just not up to the job of pulling skiers with more than two people on board. I keep the fuel on board down to thirty gallons but you still need to drag (seemingly forever) until the boat plans and you pop up. Is there anything I can do besides decarbonizing the carbs to get more performance from the 150 hp Yammie? Jock
SIM	posted 08-21-2005 04:27 PM ET (US) Jock, What I have found to work very well for these applications is a product called Permatrim Foils. They are powdercoated aluminum plate foil that bolts to the cavitation plate on your lower unit. What they do in effect is when the engine is tilted down all the way, with them installed they increase the size of that plate therfore making the boats stern lift\rise at lower boat and engine speeds. They work very well on outboard powered boats for pulling skiers, tubers ect. It lets your boat get on plane noticabley(sp) easier without nearly the bow lift you are now experiencing. There are several other designs out there....do a google on Doel Fins ect. Andy
SIM	posted 08-21-2005 04:30 PM ET (US) Jock, one more thing.......what prop are you currently running? Andy
macfam	posted 08-21-2005 05:52 PM ET (US) Jock, Do you have a spare prop? If not, It's time. Get a prop that is 2" in pitch less than what you have. For example: If you have a 19" pitch move top a 17" Use the spare for you "power prop" for sking, and heavy loads. It's not that difficult to change props. You may find that the prop you have might be a bit too agressive for your boat. Does the current prop allow you to reach the higher end of your max rpm range? If not, it's too much prop. Just be careful that when your using that prop with light loads and no skier that you don't over rev.
taypow1	posted 08-21-2005 06:36 PM ET (US) I have a vensura prop with a 19" pitch the two stroke Yamaha is raised to the third hole and a doel fin has already been installed. It's like the hull would do much better with a 175 hp or 200 hp motor to push the added weight of the upper deck added to the model in 1992. I was hoping someone would know how to get more HP out of the 150 by changing the jets on the carbs or some other mods that would not require changing motors. Jock
oroseiwhaler	posted 08-22-2005 08:06 AM ET (US) Hi taypow1, i had 2 '98 Yamaha 150 carburetted Outboards on my '98 Outrage 23. This type of motor is very powerful and i think that it should tow skiers without any problem. I immagine two problems: 1. Carburation problem, unscrew all spark plugs and check if they are all the same "dirty" If some is/are diferent than the others it means that that cylinder is firing bad. 2. Check fuel line if it's kinked, restricted, sucks air,etc. 3. If the spark plugs are heavy fouled (oily) have checked the oil pump. 4. Change all 12 spark plugs with new ones 5. Check your rpm on WOT. It has to bee 5000 to 5500 rpm with 3 persons and 30/40 gallons of fuel and safty/skiing gear. If you reach only 5000 rpm, get a 17'' propeller and try again. 6. If the engine get's full rpm while starting towing, but the boat don't accellerate you may have to test a bigger 21'' propeller due that your 19'' vensura is slipping under the extra load from the skiier. 7. Try to move all weigt forward to the bow and trim the motor all way down, this will help the boat to plane quicker. Keep us informed Best regards Chris
LHG	posted 08-22-2005 02:27 PM ET (US) Assuming the engine doesn't need work, you should be running the 17" Vensura, not 19". If water skiing is your MAIN concern, get a 5 bladed High Five in 17" pitch.
bsmotril	posted 08-22-2005 03:32 PM ET (US) One of the newer style elliptical cut slalom skies helps us old farts get on top quick from a deepwater start. BillS
taypow1	posted 08-22-2005 05:20 PM ET (US) Larry, Your exactly right I checked my prop and it is the 17" pitch Vensura. I don't think the motor has ever been decarbonized and am looking for a mechanic to give it a profesional look see. Bill, How did you know I had one of those wide fat man skiis? Does anyone know what the difference is between the 150,175 and the 200 HP Yammies? Saturday I switched props with a 175 HP Yammie ski boat that a friend owns and it completely ran the hull out of the water when pulling up skiers. His engine also has a much different sound than my 150 (throaty). Jock
bsmotril	posted 08-22-2005 05:42 PM ET (US) This might be an ideal application for one of thoese Merc variable pitch shifting props. I don't know if they are still made, but I did read some good reviews about them in ski boat applications a few years back. I think they were made after Merc introduced the Flo-torque hub adapter system, so you should be able to match it to your Yammie. The upper and lower pitch limits are adjustable, and it is basically a two speed (dual pitch) prop that shifts at an rpm that can be adjuste by varying the springs that control the shift point. BillS