1999 Yamaha 4 stroke F50TLRX running rich

[ChuckB1954]

Go lower. Ideally, with the boat loaded, in the high temperatures of summer time, with the motor trimmed up only to the best efficiency point and no further, with the throttle wide open, the motor should be able to turn at or near 6000 RPM. You might need to go to a 10 or 11 pitch if you stay with the aluminum G series of propeller.

This presumes that the motor is mounted at the optimum mounting height.

I discovered that my friends boat has a 13, so I will try that first. That will give me an idea if I have to go smaller.

[boscoe99]

My engine is running good, but at WOT I cannot reach the RPM range listed in the manual, which is 5500-6000 RPM's. I get to about 5200 RPM's wide open. I am currently running a 11 1/4 X 14 G. I am considering switching to a 11 1/8 x 13 G. Should this improve my RPM's at WOT? Or should I go to even a lower pitch?

Go lower. Ideally, with the boat loaded, in the high temperatures of summer time, with the motor trimmed up only to the best efficiency point and no further, with the throttle wide open, the motor should be able to turn at or near 6000 RPM. You might need to go to a 10 or 11 pitch if you stay with the aluminum G series of propeller.

This presumes that the motor is mounted at the optimum mounting height.

[ChuckB1954]

My engine is running good, but at WOT I cannot reach the RPM range listed in the manual, which is 5500-6000 RPM's. I get to about 5200 RPM's wide open. I am currently running a 11 1/4 X 14 G. I am considering switching to a 11 1/8 x 13 G. Should this improve my RPM's at WOT? Or should I go to even a lower pitch?

[ChuckB1954]

Wow..more typos, mainly from voice recognition send from my phone. Sorry about that!

Anyway, I looked at the prop on the 55 and the only number I see is "YC0215". Googled it but found no info.

[ChuckB1954]

I will look and see which crop is on that 55 tonight.

[ChuckB1954]

Oh I just caught it it was supposed to have red 32!

[99yam40]

I was also getting at you posted it ran 63MPH in that mealier post which is different than your original post.

need to find out what other boats like yours used when using a motor like your F50

did you find out what prop the 55 used yet?

[ChuckB1954]

Here is the prop that is on there:

20190603_195344_small.JPG


11 1/4 X 14 G
20190603_195336_small.JPG

[ChuckB1954]

do you read what you write before or after you post ?

my Xpress came with a tail on the lower unit(2 owners before me).
after I got the motor running properly ,I took the tail off and had to have my brother sit at the bow to keep it down and not porpoising.
Only way I could think to stop it was transom wedges or putting the tail back on.
I ride with a tail now.

This engine, since it was not running right, was never used on this boat until I bought it. It had the blown up 55 HP 2 stroke that was mentioned since it was new. I have only had this boat out three times since the 3 weeks or so since I have owned it, and two of those times the choke was closing at will, not to mention missing the enrichment control system. The third time I had those problems corrected. I was not concerned with reinstalling the tail. I wanted to see how my repairs affected the power. Even if I had installed the tail and I was happy with the way the boat preformed, I would have removed it again to see the difference it made with out it. This is my method, try one correction at a time. Yours, although also correct, may vary.

[99yam40]

That's how I would describe the performance of this motor, Horrible! Might not even reach plane unless someone is up front. First time I took it out, with all 4 carb bolts loose on one side (unknown to me at the time) and the choke randomly opening and closing due to un-sprung choke linkage (also unknown to me at the time), it had no trouble planing even with two people in the back. The RPMS were slightly higher and the top speed was 63 MPH. One I discovered the bolts were loose and correct it, It struggled to plane. (this was before I corrected the choke issue.) Now that the choke issue is resolved, no real difference except I lost a few MPH's and the plugs run quite normal (if anything maybe a little lean).

Don't know if this comes into play, but this engine had a hydrofoil on it at one time, but was taken off. The seller gave it to me when I bought the boat. Maybe I should put it back on?

Wide open, this engine only makes it to 5200 RPMS @ 29MPH

do you read what you write before or after you post ?

my Xpress came with a tail on the lower unit(2 owners before me).
after I got the motor running properly ,I took the tail off and had to have my brother sit at the bow to keep it down and not porpoising.
Only way I could think to stop it was transom wedges or putting the tail back on.
I ride with a tail now.

[TownsendsFJR1300]

That 1,000 RPM (and that's with a larger engine), made ALL the difference in the world.

If came with an aluminum prop (obviously NOT sea trialed before delivery). I replaced with SS and with the knowledge of the prop shop, got the correct one the first time out..


*I had a link from Yamaha re the general prop for a specific boat / hp, but that link doesn't work anymore(deleted).

Someone may have a newer link. I believe it was under "Yamaha Performance". A good prop shop, telling them what you have, RPM's etc, should be able to get you real close to where you need to be...

With another 1,000 RPM's, you should pick up a little speed too..

[ChuckB1954]

Don't know what YOUR particular engine is spec'ed at for WOT but many 4 strokes are 5,000 to 6,000.

My F150, (after being installed) was propped INCORRECTLY with a prop that MAX RPMs was 5,000 .

Performance was HORRIBLE. it would barely get on plane, nor PU a skier.

Once re-propped to get to 6,000 Max, it's a whole different engine... Would now easily jump on plane, darn near as fast as the 150 V6 Evinrude it replaced.


Once someone posts for certain, your recommended RPM range, time to get the correct prop for the max RPM...

Also what I plan to do since my buddies boat that has the original engine that came on this boat that I bought is at my house. I will look and see what prop is on his Yamaha 2 stroke and compare it to the one currently on my Yamaha 4 stroke.

[ChuckB1954]

It is 5000 to 6000 rpm.

Thank you!

[ChuckB1954]

Don't know what YOUR particular engine is spec'ed at for WOT but many 4 strokes are 5,000 to 6,000.

My F150, (after being installed) was propped INCORRECTLY with a prop that MAX RPMs was 5,000 .

Performance was HORRIBLE. it would barely get on plane, nor PU a skier.

Once re-propped to get to 6,000 Max, it's a whole different engine... Would now easily jump on plane, darn near as fast as the 150 V6 Evinrude it replaced.


Once someone posts for certain, your recommended RPM range, time to get the correct prop for the max RPM...

That's how I would describe the performance of this motor, Horrible! Might not even reach plane unless someone is up front. First time I took it out, with all 4 carb bolts loose on one side (unknown to me at the time) and the choke randomly opening and closing due to un-sprung choke linkage (also unknown to me at the time), it had no trouble planing even with two people in the back. The RPMS were slightly higher and the top speed was 63 MPH. One I discovered the bolts were loose and correct it, It struggled to plane. (this was before I corrected the choke issue.) Now that the choke issue is resolved, no real difference except I lost a few MPH's and the plugs run quite normal (if anything maybe a little lean).

Don't know if this comes into play, but this engine had a hydrofoil on it at one time, but was taken off. The seller gave it to me when I bought the boat. Maybe I should put it back on?

Wide open, this engine only makes it to 5200 RPMS @ 29MPH

[walleye1]

It is 5000 to 6000 rpm.