2120 SC UNDERPOWER WITH YAMMI F-150

[pathfinder101]

Hi All,

I have a 2004 2120 SC with a 2004 yammi F-150.. My question is that I have no problems going around 5000 - 5500 wide open throttle(depending on how the trim tabs are set) in the river and lakes... However, recently I have encountered a loss of power in wide open throttle in the ocean... I go about 3800 - 4000 rpm max (15 mph) and then gradually pick up more rpm and speed... Is it because I have to much load or, is there something I should worry about? Just wondering if any of you notice this problem only in the ocean... Much help would be well appreciated...


Thanks,

Jeff

 

[Luv2fish]

Hi All,

I have a 2004 2120 SC with a 2004 yammi F-150.. My question is that I have no problems going around 5000 - 5500 wide open throttle(depending on how the trim tabs are set) in the river and lakes... However, recently I have encountered a loss of power in wide open throttle in the ocean... I go about 3800 - 4000 rpm max (15 mph) and then gradually pick up more rpm and speed... Is it because I have to much load or, is there something I should worry about? Just wondering if any of you notice this problem only in the ocean... Much help would be well appreciated...


Thanks,

Jeff

Jeff,
I have the exact same setup and experience different performance based upon different bodies of water. I think it has much more to do with current and wind/wave condition. Strong current will certainly cause you to feel a performance hit. Also rougher conditions with the deep vee means more time with the bow cutting the water and thus lower speed/RPM. I never considered it a problem, just an artifact of the different conditions. I've got 1000 hours on my motor right now. I've often thought about whether I would get the 200 if I repowered but the reliability and affordability of the 150 is tough to give up.

Which conditions to you use the boat most often? Since I use mine the middle Chesapeake bay most often it hasn't been that big an issue.

Steve

 

[pathfinder101]

Hi Steve,

Thanks for your response!!! I know that it would run differently from the river to the ocean... I live in Northern Ca where the currents can be pretty strong in the Pacific ocean... However, the day we went it was about 3 - 4 ft swells and about 10 - 15 mph winds.. It wasn't that bad of a day and had 3 people on board (average weight per person 160 lbs x 3 = 480 lbs), 70 gallons of fuel (434 lbs), 22 gallon bait tank (200 lbs), Main motor (480 lbs), Kicker motor (115 lbs) & gear (300 lbs).. I am also using the recommended stn stl prop from Yamaha 13 3/4 x 17 prop part# 6G5-45978-03-98...

Persons 480 lbs
Fuel 434 lbs
Bait tank 200 lbs
Main Motor 480 lbs
Kicker motor 115 lbs
gear 300 lbs (including radar)
Boat 3250 lbs
Total weight 5,259 lbs

I've attached the Yamaha performance bulletin and they had the total weight at 4,924 lbs tested and it was no problem for them... So, I don't think I had to much weight on board I think... Just wondering if anybody else is having this problem....

Also, earlier that year, I had 4 people (average weight per person 160 lbs x 4= 640 lbs) about 80 gallons of gasoline (500 lbs) trolling near shore and had no problems....


Persons 640 lbs
Fuel 500 lbs
Main Motor 480 lbs
Kicker motor 115 lbs
gear 300 lbs (including radar)
Boat 3250 lbs
Total weight 5,285 lbs

Again, just wanting to get other peoples feed back with the same setup and boat... Much help would be well appreciated.....

Thanks,
Jeff

 

[DaleH]

I would make sure you can turn NO MORE THAN 200 RPMs off the maximum rated motor RPMs, with 1/3rd to 1/2 fuel, 2 people and all gear typically carried.

Most boat tests wear the WRONG (over-pitched) prop, for the 'real' world, to give better looking results for performance and fuel efficiency. Most boats carry way more of a load than any boat test ever records ...

 

[warthog5]

Jeff,
I have the exact same setup and experience different performance based upon different bodies of water. I think it has much more to do with current and wind/wave condition. Strong current will certainly cause you to feel a performance hit. Also rougher conditions with the deep vee means more time with the bow cutting the water and thus lower speed/RPM. I never considered it a problem, just an artifact of the different conditions. I've got 1000 hours on my motor right now. I've often thought about whether I would get the 200 if I repowered but the reliability and affordability of the 150 is tough to give up.

Exactly.....But the boat is Underpowered....With a larger motor you will not run the "Stem Winding Crap" out of it.

The larger motor will make the boat jump out of the hole and propel the boat at a lower RPM.

 

[pathfinder101]

Hi All,

Recap to the issue with my motor... I took it out fishing in the river last weekend and still having the idling issue.. As for the rpm, it gets up to 3900 - 4000 with no problem.. But, from 4000 and up still takes a long time.. And when it gets going it only goes to 5000 rpm at 30-31 mph...

My injectors finally arrived!!! However, the color of the injectors is green in stead of yellow? I ordered the 63P-13761-00-00 INJECTOR but the ones that came in had a -01 at the end... Anyways, installed it and ran the motor with the earmuffs hooked up.. ***!! what a difference... It idle like it was a new motor.. No problems with the rough idling and a bit of coughing... So,,, I think I might of solved the problem however, I will have to test ride the boat to make sure.. Wish me luck....

 

[pathfinder101]

Hi All,

Recapping to the issue with the under power.. I took it out in the river with 4 adults (Around 640 lbs) & 4 kids (Around 250 lbs) total weight of person 890 lbs... I resolved my under powering issue.. Soon as I forward the throttle, it started picking up real quick... It took probably about 5-8 seconds to plane and was doing 18 -20 mph and the rpm had no problem going beyond 4000 rpm... My wot was about 5300 rpm at 33-35 mph depending how I trim the tabs... I think it would do 5800 rpm at 38-39 mph with 2 person on board... I have to test it another day.... Originally, that's what it was doing, of course, depending how I trim on my tabs...

 

[Luv2fish]

Great. Thanks for the feedback on the fix.

Steve

 

[sydngoose]

Jeff,
I have the exact same setup and experience different performance based upon different bodies of water. I think it has much more to do with current and wind/wave condition. Strong current will certainly cause you to feel a performance hit. Also rougher conditions with the deep vee means more time with the bow cutting the water and thus lower speed/RPM. I never considered it a problem, just an artifact of the different conditions. I've got 1000 hours on my motor right now. I've often thought about whether I would get the 200 if I repowered but the reliability and affordability of the 150 is tough to give up.

Exactly.....But the boat is Underpowered....With a larger motor you will not run the "Stem Winding Crap" out of it.

The larger motor will make the boat jump out of the hole and propel the boat at a lower RPM.

Technically, Bobby is correct if you use the definition of "less than 75% of max HP rated" is "underpowered". 75% of 225 would be 158hp. But, I did speak to Robin at Parker, Yamaha tech support and other 2120 0wners before committing to my f150 on the 2120. It's hard to beat 3.3 nmpg at cruise. I cruise at 4200-4400 rpm at 24-25 knts. WOT is 5800 and 38mph gps. When the day comes to repower, I'll definetly go the f200xb. The biggest difference I think we'd recognize w/ the new f200 v4 is the time to plane, lower rpms at cruise, easier get up w/ a full load (less tabs).
SNG