JHONSON 9.9 WOT TOO LOW

[BRIANLODGE]

I HAVE A 2005 JHONSON 2 CLYINDER 4 STROKE BRAND NEW. MY TACK READS 4000 RPM WOT IN NEUTRAL MY HAND TACH READS 4800 RMP WOT IN NEUTRAL. I THINK THIS IS TOO LOW. WHAT SHOULD IT BE?? I THINK 5500 IS ABOUT RIGHT. SO HOW DO I ADJUST THE RPM IN NEUTRAL. I HAVE CHECKED AND THE THROTTLE IS OPEN 100 PERCENT SO THERE MUST BE A REV LIMITER OR SOMETHING RESTRICTING HIGHER RPM'S. PLEASE CAN SOMEONE HELP. THE MARINA SAID 4800 IS FINE AND ARE TOO BUSY TO HELP ME OUT.

 

[R.Johnson]

Re: JHONSON 9.9 WOT TOO LOW

I can't believe you told a dealer you were hitting 4800 in neutral, and looking for more. You do not take an engine to the limit in neutral. Your lucky your not picking it up with a broom.

 

[CATransplant]

Re: JHONSON 9.9 WOT TOO LOW

Wierd. Would you floor the gas on your car or truck in neutral? I sure wouldn't. Doing that is just begging for a rod to come loose.<br /><br />There may well be a limiter on your engine. Given the number of people who post here about revving their outboards in neutral, it sounds like a good idea.<br /><br />The RPM's your engine makes at WOT in neutral is completely useless information. The only measurement that counts is the speed the engine's turning in forward at WOT...on the boat...in the water.<br /><br />Take care of your expensive 9.9 hp outboard. Don't abuse it or it will be an expensive 9.9 hp pile of junk.

 

[BRIANLODGE]

Re: JHONSON 9.9 WOT TOO LOW

OK OK. IT WAS ONLY BRIEF TO CHECK WHAT I HAD SUSPECTED. I WAS WOT IN FORWARD AND UNDER 4000 RPM AND THOUGHT I WAS LIMITED BY THE ENGINE AND NOT THE PROP. WHICH PROVED TO BE TRUE. SO HOW DO I GET THE RPM'S UP TO THE 5000-5500 MARK OR IS THE 4800 WHERE IT SHOULD BE?? NO ONE HAS TOLD ME WHAT I SHOULD TACH OUT AT!!!!

 

[CATransplant]

Re: JHONSON 9.9 WOT TOO LOW

Please type in something other than all caps. It looks like SHOUTING in these forums. Lots of people who might help you will not answer posts in all caps.<br /><br />You want to know what the engine's rated WOT rpm's are. It's a new engine, right? Look in the owner's manual. You'll find that where you find the specifications for the outboard, probably under the HP rating data, which is generally list as something like:<br /><br />9.9 hp at nnnn RPM.<br /><br />That RPM is the number you want. I do not know the rated RPMs for your 4-stroke 9.9.

 

[BRIANLODGE]

Re: JHONSON 9.9 WOT TOO LOW

I WAS ALSO JUST INFORMED OVER THE PHONE FROM ANOHTER MARINA THERE IS A NEUTRAL LIMITER AND STOPS RPMS AT THE 4000 MARK. HE SAID MY HAND TACH IS PROBABLY OFF AND TO USE THE ONE ON THE BOAT. HE SAID TO CHECK LINKAGE TO SEE IF WHEN IN FORWARD THE LIMIT IS DISABLED. HE BELIVES THE REV LIMITER IS NOT BEING DISABLED WHEN IN FORWARD AND THAT'S MY PROBLEM. IF NOT THEN TO CHANGE MY PROP FROM 9 DOWN TO 7. CAN ANYONE CONFIRM ANY OF THIS TO BE TRUE?????

 

[BRIANLODGE]

Re: JHONSON 9.9 WOT TOO LOW

Sorry about the all caps. I read the post after I re-posted. I was on the phone with another marina trying to get some more info. <br />manual states min WOT of 5000 max of 6000 and recommended of 5500.

 

[CATransplant]

Re: JHONSON 9.9 WOT TOO LOW

It is very unlikely that a new motor would have a problem with its linkage, with regard to the speed limiter. I suspect your hand tach is incorrect. Use the one on your boat. Take the boat out and run it at WOT and report the engine RPMs under those conditions. They are the only relevant numbers. Your neutral numbers are meaningless.

 

[BRIANLODGE]

Re: JHONSON 9.9 WOT TOO LOW

Sorry about the all caps. I read the post after I re-posted. I was on the phone with another marina trying to get some more info. <br />manual states min WOT of 5000 max of 6000 and recommended of 5500.

 

[BRIANLODGE]

Re: JHONSON 9.9 WOT TOO LOW

Ok. Back to square one. At WOT in forward I am at 4000 RPM using the boats tach. I have a 9.5 x 9 prop. Should I try a 9.5 x 7??? Motor does not seemed bogged down at all. Other identical boats sure sound like higher rpm's. Just haven't had the chance to ask to take a look at their prop size. Or could it be the rev limiter? When I back off the throttle just a little it runs better????

 

[CATransplant]

Re: JHONSON 9.9 WOT TOO LOW

You'd get more revs out of the 7-pitch prop, but that may not be the best solution. As I said, to make that determination, we'd need to know some information about your boat and how you have the motor set up.<br /><br />Where is the A/V plate (horizontal plate above the prop) in relationship to the keel of the boat?<br /><br />What tilt angle is the outboard set at? I believe these have a series of holes or steps that let you tilt the motor for running at different angles.<br /><br />What kind of boat are you using your 9.9 on? That's also very critical. What size? What hull design.<br /><br />It may be that it's just a matter of proper setup to get your 9.9 performing properly. Changing props may well not be the answer.

 

[BRIANLODGE]

Re: JHONSON 9.9 WOT TOO LOW

it's a 20 ft pontoon boat. The tilt of the motor is all the way down (which really apears to be almost verticle.) Your first question really does not apply to a pontoon, but it would apear to be 6 inches or so below the toons. I was afraid if I tilt it up a hole or 2 it will cavitate.

 

[Goodoleboy]

Re: JHONSON 9.9 WOT TOO LOW

If it were me I would borrow a smaller prop. I would also try raseing the motor up some get the cav plate close to surface of water.<br /><br />I would also try runing the motor on the second hole from bottom. If it helps rpm Id try the third one. If no help go back to two.<br /><br />In conclusion I beleive your motor is setting to deep in the water. Its tilted in to far and pushing down on the front of your pontoons.<br /><br />Its just working its little hind end off trying to do its job.

 

[BRIANLODGE]

Re: JHONSON 9.9 WOT TOO LOW

Sounds reasonable. I hit the water saturday. First I'll try the tilt woking my way back then maybe raising the motor. (that's not an easy task on this boat, but tilt is simple. I may ask to borrow a 7 pitch prop if the tilt fails.

 

[CATransplant]

Re: JHONSON 9.9 WOT TOO LOW

OK, now that you say the motor's on a pontoon, then I'll bet you're overpropped. The little guy just can't get up to full engine speed pushing something that size. <br /><br />I'd go ahead and grab the 7-pitch prop for that application. I'd also try tilting the motor out a notch or two.<br /><br />The 9-pitch prop would probably work fine for a little aluminum boat, but a 20' pontoon boat is another matter. <br /><br />I'm betting a combination of the 7" prop and a bit of trim adjustment will get your 9.9 up to speed. Of course, you still won't be going fast, but the engine won't be working its heart out, either.

 

[R.Johnson]

Re: JHONSON 9.9 WOT TOO LOW

A 9.9 motor on a 20 ft. pontoon is a bad combination. That engine will lug every foot of the way no matter what prop you put on it. You can't push around all of that weight with 10 HP. Think of this rule of thumb on a boat. " Double the speed, Eight times the resistance" That holds true on most all water going vessel's.

 

[R.Johnson]

Re: JHONSON 9.9 WOT TOO LOW

A 9.9 motor on a 20 ft. pontoon is a bad combination. That engine will lug every foot of the way no matter what prop you put on it. You can't push around all of that weight with 10 HP. Think of this rule of thumb on a boat. " Double the speed, Eight times the resistance" That holds true on most all water going vessel's.

 

[Solittle]

Re: JHONSON 9.9 WOT TOO LOW

See if you can absorb the hit and swap that 9.9 for a 50hp. Changing the prop will help it spin faster but it won't make a heck of a lot of difference in pushing a 20' pontoon - - unless you are not in a hurry to get anywhere.

 

[pontoon chief]

Re: JHONSON 9.9 WOT TOO LOW

Both Merc and Yamaha make a High Thrust 9.9 Four stroke that work good on a pontoon boat.They don"t have a High RPM range but are great for pushing large boats around 9-9 MPH.<br />The props are much larger that the standard prop.

 

[umblecumbuz]

Re: JHONSON 9.9 WOT TOO LOW

Agree with R. Johnson ...<br /><br />Try for a bigger motor. (The Merc and Yammy motors mentioned by Patrick are dedicated motors - not general-purpose outboards like your 9.9)