Carb needle vale different sizes?

[MillsK277]

I've had issues with my fuel system for the past two years.

I've replaced the fuel pump and this is the second time I am cleaning the carbs.

2001 60 HP Yamaha 2 stroke 60TLRZ

This time I've noticed that the top carb needle vale is just a bit longer than the other two. When I position the float in the position that opens the needle valve, I cannot blow through the inlet. I am assuming that the needle valve may have been replaced (I'm the second owner).

Has anyone noticed a difference in the needle valve sizes?

[MillsK277]

I should note that the engine idles rough, and bogs down when at full throttle. It runs just fine at half throttle. It appears that it is not running on all 3 cylinders.

[boscoe99]

Same part number float needle valve is used for all three carburetors. They should all be of the same length.

If air cannot flow across the valve when the float is down then I don't see how gasoline can. If gasoline cannot enter the float bowl then I don't see the carburetor feeding gasoline to the applicable cylinder.

When you say that you don't think that it is running on all three cylinders have you determined which of the three is not firing? And why? That is, is it spark related or fuel related? Have you tried misting a bit of gasoline into the inlet of the the carburetors to see if it makes any difference in how the motor is running?

The carburetors on your model appear to use a replaceable needle valve seat. Is that correct and is the seat properly installed?

[99yam40]

look up your motor parts and see if the needles are all the same, my thoughts they would be the same.

you may need to make sure all of the carbs are the right ones on your motor if someone has been swapping parts

[MillsK277]

Yes, it was a different needle. I purchased a new valve and seat. It tends to stick a little in the closed position. At least it's not as smooth as the other two. maybe the new piece needs to get worn in a bit. it does open if you jiggle the carb just a bit.

I ran with this needle valve for 2 years before I starting seeing trouble. Not sure how or why. At any rate I hope this fixes my fuel problems.

Hope to get it running this afternoon.

[MillsK277]

sigh... and now I have a backfire on my third cylinder. This is the cylinder I put the new needle and seat in. It was sticking just a bit.

[TownsendsFJR1300]

sigh... and now I have a backfire on my third cylinder. This is the cylinder I put the new needle and seat in. It was sticking just a bit.

Did you clean the bore the needle resides in?

A little bit of compound, toothpaste on the end of a Q-tip, attach to a drill motor will clean / polish that hole real quick..

Is there a float "drop" adjustment on the float and if so, looks ok?

[MillsK277]

I didn't. I figured...brand new seat, it must be fine.

I'll polish it up in the morning. Hope to be fishing by noon.

No float adjustment. Wish the float and needle we're directly connected.

[panasonic]

I pretty sure Scott meant polish the bore that the needle moves up and down in so it moves smoothly without hanging up. The needle seat should not have to be polished as it is brand new.

[TownsendsFJR1300]

I pretty sure Scott meant polish the bore that the needle moves up and down in so it moves smoothly without hanging up. The needle seat should not have to be polished as it is brand new.

Exactly...Edited my below post.

Once repaired, you may want to run Yamaha's RingFree (and a fuel stabilizer). The RF will help keep the fuel system clean: https://www.shopyamaha.com/product/d...?b=Search&d=34

BTW, I had the same issue last week, (10HP Tecumseh generator engine) on a customers carb. Once polished (and it looked good), it was nice and shiny and NO more hanging up

An extreme result of varnish build up:


After an Ultra Sonic cleaning:

[panasonic]

Exactly...Edited my below post.

Once repaired, you may want to run Yamaha's RingFree (and a fuel stabilizer). The RF will help keep the fuel system clean: https://www.shopyamaha.com/product/d...?b=Search&d=34

BTW, I had the same issue last week, (10HP Tecumseh generator engine) on a customers carb. Once polished (and it looked good), it was nice and shiny and NO more hanging up

An extreme result of varnish build up:


After an Ultra Sonic cleaning:

What do you use in your ultrasonic cleaner Scott? What ever it is....it does a good job...

[99yam40]

I often wondered how well it cleans the passages under those disc/plugs without pulling them out.
Has to be better than just soaking things and blowing out

[TownsendsFJR1300]

What do you use in your ultrasonic cleaner Scott? What ever it is....it does a good job...

I use a 50/50 mix of Simple Green and water. And that's a bit on the strong side...

That carb got (3) 20 minute "soaks".

Never removed a plug in my life...

The parts get sprayed with air then with a shot of brake cleaner thru the orifices. I also have a carb jet cleaning "needles" (which gets run thru).

The super tiny orifices, (usually 3- idle circuit) on the engine side of the butterfly, (which takes my SMALLEST NEEDLE), after the needle, gets a shot of carb cleaner till I see it come out elsewhere(just to make sure).

Unfortunately, for this carb (after I did the cleaning) the float leaked (ingested fuel over night) and the needle seat disintegrated from old age (kinda looked like a white plastic something??)

This customer brought me 5 generators, 3 were fixed, 2 not worth fixing, 4 chain saws, 3 now running, a blower and hedge trimmer both now running...

ALL carbs needed cleaning, the small engines all needed fuel lines.


**One other generator (a neighbor) asked me to fix her generator. Her husband passed about a year ago. Got it running but found a dark grayish, looked like sealer, in the fuel tank (tank 3/4 full). Once I got it out, it hardened up big time. I noticed Stabil on a shelf in the garage while there and can only assume this WAS STABIL... There was no damage to the tank what so ever....

It was "dinked" with by her husband (could see parts not put back right, stripped bolt, etc). It was apparently running too rich, fouling the plug/dying after an hour. Put a spare carb I had on it, ran great!!! Nice color on the spark plug after an hour running.. The new carb should be in Tuesday...

[99yam40]

Most of the time those disc/plugs are over the 3 idle/off idle ports. some I have pulled had real nasty stuff in there like the bowl in pic you posted
after market carbs are getting cheap, but do not know if they are as good as original ones in the long run

do you think the cleaners used attacked the plastic float

[TownsendsFJR1300]

cleaners used attacked the plastic float[/B]

As old as this particular carburetor is, it's possible the needle seat failed with cleaning. Carb cleaner is way more aggressive than the Simple Green and I NEVER used carb cleaner on the seat, just brake cleaner(much less aggressive)..

**The needle seat actually RAISED a bit (from the carb body), IE, with the needle in, the float was now hanging WAY DOWN fully closed. I tried tapping the seat back in gently but it fell apart.

I checked the float, held under water, first, it was fine. It took over-night for the float to fill maybe 1/4 with fuel (and then gas was running out the throat with the float NOT floating)..

It IS the only carb, plastic (or other) part (the seat), I've seen fail like this.

Most of these machines he brought me are MANY YEARS old.

That particular engine, the rubber engine mounts were broke / rotted. I had to literally vise grip them together to keep the engine from falling off.... (He brought me a pile of old crap-which I've since discussed with him.)