Yamaha 150 TXRC carb float question

[99yam40]

My thoughts are that
Manuals gave been printed with wrong info before and will be again in the future.
My Yamaha service manual gave the wrong steps for link and syncing.

When someone with a lot of experience tells me something different than the manual I would tend to believe him

[zenoahphobic]

My thoughts are that
Manuals gave been printed with wrong info before and will be again in the future.
My Yamaha service manual gave the wrong steps for link and syncing.

When someone with a lot of experience tells me something different than the manual I would tend to believe him

Then why does'nt he simply say the manual is incorrect, that that is why we should trust him?

[rodbolt17]

because I don't have the manual , I can tell you that its best to set the float with the gasket in place.
that way you cannot mix up the floats after removing them to install the gasket.

some things are simply obvious.
or should be.

[zenoahphobic]

Psalm 99, I am lost, I hope you know what measurement with the gasket on?

[TownsendsFJR1300]

With the gaskets installed, the floats WERE SET correctly. At least two needles/seats were leaking.

And, if you think about it, once the carb is closed up, the gasket has the bowl slightly farther away from the body-makes sense..

I can show several instances in a GENUINE Yamaha motorcycle shop manual where it was flat wrong. IE, when checking valve lash(shim and bucket), Yamaha has you turning the engine BACKWARDS!!!

[TownsendsFJR1300]

I have the same engine and its runs great at all speeds except idle...

Is there anyway to pull the jet out and clean and re install without pulling the carbs off all together?

And if so can someone please send me in the right direction and where that idle jet is located on the carb?

I have done motorcycle carbs but they are always under the float and it had to be taken apart..

Thanks
Dan

Dan, If you could start your own thread would be better. It tends to confuse issues between two different engines on the same thread.

Here's your carb parts fisch; 2004 150TXRC Yamaha Outboard CARBURETOR Diagram and Parts

Jet locations are on there and yes, you do have to pull the carbs... No different than the bike, and probably easier to get to once off.. Jet #10 is your slow speed jet. I'd pull all the jets while there and VISUALLY INSPECT at the least..

[boscoe99]

What's wrong with the setting to his manual (without gasket) after he fixes the leaking needle and seat?

That is what I would do.

As much as I am critical of crappy Yamaha data, in this case I believe the SM is correct. There are too many other SM's that provide the same information. That is, the float height is checked from the bottom of the carburetor body and not from a gasket.

I suspect that in lieu of installing a new float valve (and thoroughly cleaning the valve seat) many just change the float height to make the problem go away. Unfortunately, this is just a band aid approach. Problem is, while a leaking seat problem may be solved the fuel level in the bowl will be affected which can cause other issues.

I would install new valves, after making sure the seat is clean, and set the float height per the SM. I suspect the problem will go away. If not, maybe change the float height as necessary to solve the problem but not to the extent that measuring from a gasket would change it.

[Psalm 99]

Engine back together (again)

Could probably take carbs off and replace in my sleep now as I've had to do it so many times. If I had kept the float set with the gaskets in place, there would have been significantly more force applied to the needle valves and life would have been easier. Setting to the factory specs required really good cleaning of the needles and orifices to get a proper seal. Engine now is running strong, idling well with less vibration and I was able to loosen the idle adjustment screw noticeably to achieve the same idle RPM's (about 750). Possibly running leaner with better fuel economy (time will tell). Still concerned about the needle valve(s) leaking with time, however though with the carb removed I pressurized the seal with gravity (floats upside-down) and Mityvac'ed the fuel intake tube up to 15 psig with no leakage. Leaving assembled overnight also may have helped by slightly swelling the needle point with gas. Holds ok with priming bulb stiff but I'll order new needles just in case. Although I just visually inspected the idle jets, you access them thru the brass screws at the carb base. You would need to remove the carb(s) to do this. Thanks to all for the good advice - Al

[dbranco00]

Where are the pilot jets or the idle jets located? Can you take a picture?
IS this correct that there are 2 idle jets per carb??

And where are they located, was told to take them out and spray some sea foam in them let sit overnight and start up next day. Should 90% of the time clean them out. The boat has great performance after 1300 rpms, just wont stay running at idle...

Ordered a manual but it take 10 days to get here. OR can you take a picture of your manual if you have one..

Thanks
Dan

[zenoahphobic]

Psalm be careful using the upside down and float weight to seat the needle.
The maximum force in a design is that of the weight of the fuel displaced by the float floating.
A small therefore exerts a very small force before shutting the valve. Inversion can exert more force and damage the seats slightly.

[TownsendsFJR1300]

Where are the pilot jets or the idle jets located? Can you take a picture?
IS this correct that there are 2 idle jets per carb??

And where are they located, was told to take them out and spray some sea foam in them let sit overnight and start up next day. Should 90% of the time clean them out. The boat has great performance after 1300 rpms, just wont stay running at idle...

Click on the link I posted in post #21. There's a picture there.. The slow jets are parts #10, and yes one jet per venturi (3, two barrel carbs). Simply pull them all out and use carb cleaner on them. Once you can see thru them, their good.

The regular use of Yamaha's "RINGFREE" is MUCH,MUCH BETTER than Seafoam :

https://www.shopyamaha.com/product/d...?b=Search&d=34

**If your reluctant to pull the carbs apart, running 2x the recommended amount of Ringfree may clean out the jets(depending on how clogged they are). It will take some time running if going this route.

Run RF regularly (with fuel stabilizer) and you won't be cleaning carbs anymore...


Sorry for the hijack...

[dbranco00]

The issue running 2 times the ring fire is that there is 90 gallons of fuel in the tank....

[TownsendsFJR1300]

The issue running 2 times the ring fire is that there is 90 gallons of fuel in the tank....

Hook up a 6 gallon tank temporarily...

[dbranco00]

Did not even think of that!! Damn. That's Right THE Oil Gets INJECTED After So I Could Run Right Off THE Bulb With REG gas.
I also already dumped 3 cans of sea foam in tank

[TownsendsFJR1300]

Psalm be careful using the upside down and float weight to seat the needle.
The maximum force in a design is that of the weight of the fuel displaced by the float floating.
A small therefore exerts a very small force before shutting the valve. Inversion can exert more force and damage the seats slightly.

I respectfully disagree.

Most carb flat adjustments are done just as directed by the shop manual, upside down, gravity only.

It takes a bit of intentional force to change the float level tangs.

Even if you get slightly more pressure on the needle seat with the float closing with fluid, the better!

That little bit (if even true) is minimal and designed that way.

With that said, generally, if I have a potential issue with a leaky valve, I'll hook up a small auxiliary tank to the carb (off the engine). Leave the float bowl off, then flip the carb to the correct position. Then open and close the float gently. You'll see if its holding or not.

Needles and seats do wear over time. IMO, if in doubt, just change them out, adjust with gasket on, (test if need be) and be done with it.