Max rpms are only 4200 when wide open. 2001,115 yamaha

[JerEazy1]

NEVER ASSUME anything...

He's had it for a year and just starting to work on it.

He was LAST told it turned 5,500 PRIOR to him obtaining it. NOTHING MENTIONED about in-between owners.

And there was no mention of simply going to WOT out of the water on muffs to obtain 4,400 RPM's.

Most folks know it must be on the water, loaded, etc to get an accurate WOT #.

The OP is apparently aware of it as he's mentioned 5,500 but only gets to 4400..

+1 with Yam99's last post, re same prop, same 5,500RPM's?

Hopefully it IS a simple prop change.

No, there was no mention of hose - that was because he said he's no mechanic - just a weekend warrior. Call it a warning label as I've watched people start their engines out of the water, not on a hose and rev the engines at boat ramps. And then launch and drive away like it was completely normal. I'm not saying the OP doesn't know to do it. But, better to say it.

And no, there was no mention of in-between owners. But there was mentions of fuel filters, carb cleaning and draining etc etc....

Don't over complicate it.

When an outboard gets to the upper end of the RPM Curve, (4200 RPMs) but does not reach max recommended RPM; the prop is the most likely issue. Yes I am making an assumption, but it is an educated one.

If the engine would only rev to 2500 or 3500 then there would be other engine issues to potentially look into (is the tach set right would still be next before jumping into the engine). If it sputtered, surged, cut on and off, then yes. Explore the engine. But, he stated it's running "much better now" and at 4200 he's not that far out of spec. Re-prop, get the revs right and enjoy the boat.

If you hear hoof beats; think horses. Not zebras.

[99yam40]

here is a 17'6" glass rig weighing in at 2500lbs during test ,running a 21 pitch prop that does well WOT hitting 5600.

http://yamahaoutboards.com/sites/def...80-115tlrc.pdf

So not sure his 4 blade 20 prop is too much, and he was not sure if it was a 20 or 26
not enough info for me to say
anyone know what his boat weighs?

and here is another one
http://yamahaoutboards.com/sites/def...5xl-115tlr.pdf

[pstephens46]

First off tank you all very much for the help!

I've never seen it go past 4200.. before I did the recent maintenance it would stall out if I ran above 3500 rpms for long, but after replacing the fuel pump and cleaning and replacing some parts on the carburetor, that problem went away..

The boat did sit for several years before I got it a little over a year ago and got it running again. I flushed out the fuel lines and drained the tank when i got it. but nothing other than nonE has been run through it, so I'm told, and thats all i use. But judging from how clean the carb was i belive it.

These are the hoof beats I am hearing!

[JerEazy1]

here is a 17'6" glass rig weighing in at 2500lbs during test ,running a 21 pitch prop that does well WOT hitting 5600.

http://yamahaoutboards.com/sites/def...80-115tlrc.pdf

So not sure his 4 blade 20 prop is too much, and he was not sure if it was a 20 or 26
not enough info for me to say
anyone know what his boat weighs?

and here is another one
http://yamahaoutboards.com/sites/def...5xl-115tlr.pdf

Those are great - but you and I both know there is more involved in what prop should be on a boat than just the weight of the vessel.

This is what forums are for. People express opinions and ideas and hopefully a solution is found. If OP wants to work on the engine to see if it fixes it, and it does; then great! If he decides to go with a different prop and see if there is a solution, also wonderful. Heck, we might all be wrong and it's something like the throttle not actually opening fully when he control is placed at WOT (rental guy here did something like that to keep people from beating the crap outta his engines.)

All I am saying is that every time this situation has arisen in my experience (engine that runs well - not hitting WOT RPM range) Adjusting the prop was the solution. New to this forum, new to working on yamaha motors - but not new to boating.

Hopefully once solved, we'll all be informed and the information for anyone who runs into the issue in the future.

[TownsendsFJR1300]

Any engine, especially marine with carbs and ethanol fuel, that's been sitting for YEARS, WILL have carb issues, that's a given...

Agreed, if the throttle cable is not adjusted correctly, it won't rev fully.

People do stupid stuff, see it here ALL the time. Folks here have to assume certain things are correct, IE, the throttle DOES INDEED OPEN. May, may not. Might be the issue here.

To go straight to re-propping for an engine that's sat for years, other things (IMO) should be checked, cleaned, etc first (unless you enjoy throwing $ at the engine).

Ask 99Yam about his engine... The PO re-jetted the engine (and wasn't told). Took him quite awhile to find it out and fix the PO's "fix".

I can't count how many times a "carb was cleaned". When nailed down to EXACTLY how it was cleaned, we'd get sprayed it with carb cleaner, no jets ever pulled, jets were eventually found to be clogged (not cleaned as we were told)....

Start with basic stuff, the more information, the better...

[JerEazy1]

These are the hoof beats I am hearing!

And your thoughts on those sounds are?

[99yam40]

He either needs to find a shop with a test wheel for his motor so it can be properly tested without doing anything else on the motor,
or contact prop gods or some other prop guru and give them all of his info to see what they think about the prop he is running.
But then he will need to know stuff he may not know right now


Oh the PO of my motor did not rejet my motor they drilled the jets, so the numbers were correct, but the holes were not.
I had to buy one new jet just to verify what the correct size hole was, because no one could tell me where to find that info.

took me about a year of testing everything and cleaning carbs many times trying to figure out why I could not make that high speed miss go away

ended up replacing all 3 main jets and that fixed it finally.

[JerEazy1]

Any engine, especially marine with carbs and ethanol fuel, that's been sitting for YEARS, WILL have carb issues, that's a given...

Agreed, if the throttle cable is not adjusted correctly, it won't rev fully.

People do stupid stuff, see it here ALL the time. Folks here have to assume certain things are correct, IE, the throttle DOES INDEED OPEN. May, may not. Might be the issue here.

To go straight to re-propping for an engine that's sat for years, other things (IMO) should be checked, cleaned, etc first (unless you enjoy throwing $ at the engine).

Ask 99Yam about his engine... The PO re-jetted the engine (and wasn't told). Took him quite awhile to find it out and fix the PO's "fix".

I can't count how many times a "carb was cleaned". When nailed down to EXACTLY how it was cleaned, we'd get sprayed it with carb cleaner, no jets ever pulled, jets were eventually found to be clogged (not cleaned as we were told)....

Start with basic stuff, the more information, the better...

Whew - I am really defending my stance here.... I wasn't saying the OPs problem was a throttle cable. I was saying that it could be anything! It's process of elimination. But why pull apart the carbs and fuel system or any part of the engine or fuel system again? He's already pulled the carbs, new fuel pump, filters, plugs, and seafoam. Why not move onto the next possible solution before going over his steps again?

The most basic thing on a boat motor is the propeller.... A new aluminum prop is not expensive and extremely easy to install. Heck, one on craigslist might cost what $20, $40? Maybe he has a friend with a boat that could let him use one? Call the local dealer and see if they have a test prop? I actually might have a 15p in my garage that would fit his motor he could try out! (seriously - i might... i'll check the splines on it when i get home. some of the old Johnson props fit on the yamis if i'm remembering my prop history)

Being that everything he is running off of is hearsay. He was told that it hit 5200 - he never saw it and it's never done it for him. I was told earlier not to assume anything. So why should he assume that he was told the truth and that prop is correct?

[JerEazy1]

Oh the PO of my motor did not rejet my motor they drilled the jets, so the numbers were correct, but the holes were not.
I had to buy one new jet just to verify what the correct size hole was, because no one could tell me where to find that info.

took me about a year of testing everything and cleaning carbs many times trying to figure out why I could not make that high speed miss go away

ended up replacing all 3 main jets and that fixed it finally.

Off topic - That was just messed up of the previous owner - nicely done on the fix

[99yam40]

the one that told him it hit 5200 might have also said what prop it was running at the time, that was all I was trying to get him to tell us.
does he know or not

[pstephens46]

And your thoughts on those sounds are?

I mentioned the test wheel earlier. To rule out engine issues. Also offered an idea of where to find one.

[TownsendsFJR1300]

I mentioned the test wheel earlier. To rule out engine issues. Also offered an idea of where to find one.

A test wheel would in-deed rule a bunch out ASAP, if he can find one.

[Jason2tpa]

here is a 17'6" glass rig weighing in at 2500lbs during test ,running a 21 pitch prop that does well WOT hitting 5600.

http://yamahaoutboards.com/sites/def...80-115tlrc.pdf

So not sure his 4 blade 20 prop is too much, and he was not sure if it was a 20 or 26
not enough info for me to say
anyone know what his boat weighs?

and here is another one
http://yamahaoutboards.com/sites/def...5xl-115tlr.pdf

Action craft hulls are fairly lightweight. An 18' dry weight hull is round 1,000 lbs.

The OPs action craft hull length and dry weight is very similar to my hull. We also have the same engine. When I had a 3 blade 21" pitch the most rpm I turned was 4700. I dropped down to a 3 blade 18" and now turn 5400. So by comparison, it's not hard for me to believe his 20" 4 blade will only turn 4200.

[Mr.nitrox]

Sorry had a busy monday..
I did remove and clean the two main jets in the carb and could see day llight through them. There were two smaller jets that i did not remove for fear of how to remove them without damaging. but i could see dayllight through the two or three pin holes i could see and sprayed them thoroughly.

The engine sounds great. No sputtering, no symtoms at all. And it sounds like its running with throttle wide open. All the tests ive done have been on the water. I was thinking of purchasing a 3 blade prop anyway just to have the option to go a little faster when i feel like it. I think i will try a 15 or 16 pitch but im having my buddie check his prop tomorrow and let me know what hes running so i can borrow it if its in the range im looking for and compatible.

I may be able to test it out as soon as tomorrow afternoon if i can find one. I will report back with my findings.

Thanks again

[Mr.nitrox]

Im also trying to get some more info from the previous owner whos my uncle. So ill have more info on that soon as well.