Carburetor bowl drain screw on 25 hp 2 stroke Yamaha?

[jspriddy]

I have a '94 Yamaha 25 hp single carb 2 stroke engine. It's stored away from a water supply so I want to completely drain the carburetor of fuel for the winter. I've attached a photo. Is the bright brass screw with the spring the drain? I was afraid to fool with since it looked like an adjustment screw.

IF it is a drain, is just backed out enough to drain, or what?

 

[boscoe99]

Re: Carburetor bowl drain screw on 25 hp 2 stroke Yamaha?

Apparently you have a C25, not a 25 Yamaha.

Let the Yamaha parts catalog be your friend.

Yes, that is the drain screw. I would remove it completely, taking care not to lose any parts while doing so. Then, I would rotate the motor side to side, and up and down, as necessary to get the drain outlet to be on the very bottom.

 

[jspriddy]

Re: Carburetor bowl drain screw on 25 hp 2 stroke Yamaha?

Apparently you have a C25, not a 25 Yamaha.

Let the Yamaha parts catalog be your friend.

Yes, that is the drain screw. I would remove it completely, taking care not to lose any parts while doing so. Then, I would rotate the motor side to side, and up and down, as necessary to get the drain outlet to be on the very bottom.[

OK. Thanks. I'd about figured out that was all it could be. I just have an aversion to turning screws with springs, unless I know exactly what it is.

By the way, the motor is a C25ELRS, but it is a 25 horse power Yamaha. However, I think you gouging me to be more specific. Gotcha.

Thanks,

John

 

[boscoe99]

Re: Carburetor bowl drain screw on 25 hp 2 stroke Yamaha?

OK. Thanks. I'd about figured out that was all it could be. I just have an aversion to turning screws with springs, unless I know exactly what it is.

By the way, the motor is a C25ELRS, but it is a 25 horse power Yamaha. However, I think you gouging me to be more specific. Gotcha.

Thanks,

John

I was. Reason being that there are several different Yamaha's in 25HP models. The C25 is the one with just one carburetor. It helps to know specifically which motor is being asked about.

 

[jspriddy]

Re: Carburetor bowl drain screw on 25 hp 2 stroke Yamaha?

I was. Reason being that there are several different Yamaha's in 25HP models. The C25 is the one with just one carburetor. It helps to know specifically which motor is being asked about.

Ah, but I did say it was a 2 cylinder, single carb. (My friends call me "Mr. Know-It-All", so my ego requires me to be at least partly right, or in the absence of being even partly right, have an excuse, however lame it may be). But you're right-"C25" is more specific.

Thank you for your time, I'll drain it as soon as time permits,

John

 

[robert graham]

Re: Carburetor bowl drain screw on 25 hp 2 stroke Yamaha?

Lay a rag under the carb while removing screw to catch it, spring or O-ring during removal....it's very easy to drop parts down into inaccessible places. When you get the screw out, pump your primer bulb a few times to "flush" float chamber....then return screw....carb draining is very good preventive maintenance......

 

[jspriddy]

Re: Carburetor bowl drain screw on 25 hp 2 stroke Yamaha?

Lay a rag under the carb while removing screw to catch it, spring or O-ring during removal....it's very easy to drop parts down into inaccessible places. When you get the screw out, pump your primer bulb a few times to "flush" float chamber....then return screw....carb draining is very good preventive maintenance......

Thanks. That would be a bad spot to drop small parts. I will flush it out. I ran it empty earlier (unhooked gas line) which I suppose is an exercise in futility if you're going to drain it, anyway?

John

 

[jerryjerry05]

Re: Carburetor bowl drain screw on 25 hp 2 stroke Yamaha?

Makes me wonder why it has a spring on the "drain screw"??
Usually it's just a screw and gasket.
When you undo it?
Try to screw it in and see if it will go in any farther.
Remember the turns if it goes in.
Possible it's some kind of metering screw??
Don't know for sure but the spring on the screw makes me wonder??

 

[jspriddy]

Re: Carburetor bowl drain screw on 25 hp 2 stroke Yamaha?

Makes me wonder why it has a spring on the "drain screw"??
Usually it's just a screw and gasket.
When you undo it?
Try to screw it in and see if it will go in any farther.
Remember the turns if it goes in.
Possible it's some kind of metering screw??
Don't know for sure but the spring on the screw makes me wonder??

I'll see if it will turn any further, but I doubt it. This morning I ran into the man who rebuilt the carburetor last spring, and he confirmed what everyone above said-that it was just a drain.

By the way, he recommended filling the bowl with pure Stabil for the winter, and flushing it out next spring. Don't guess it could hurt.

Thanks,

John

 

[robert graham]

Re: Carburetor bowl drain screw on 25 hp 2 stroke Yamaha?

Draining each carb is Much better than "running fuel out",which actually leaves fuel/water/contaminates in float chamber....I always place a clean white rag under each carb during draining to see what kind of trash may be draining out.....please be careful not to over tighten/strip threads on drain screws when replacing then....good luck!

 

[jspriddy]

Re: Carburetor bowl drain screw on 25 hp 2 stroke Yamaha?

Draining each carb is Much better than "running fuel out",which actually leaves fuel/water/contaminates in float chamber....I always place a clean white rag under each carb during draining to see what kind of trash may be draining out.....please be careful not to over tighten/strip threads on drain screws when replacing then....good luck!

Will watch the over-tightening.

Thanks,

JOhn

 

[jerryjerry05]

Re: Carburetor bowl drain screw on 25 hp 2 stroke Yamaha?

Running out of fuel isin't good for the cylinders or bearings.
The gas/oil lubes the moving parts.
You run it out of lube,bad things can happen.
My neighbors 200 had a problem with the oil system.
No lube got to the system and he didn't heed the warnings.
Now he needs a powerhead.

 

[boscoe99]

Re: Carburetor bowl drain screw on 25 hp 2 stroke Yamaha?

Running out of fuel isin't good for the cylinders or bearings.
The gas/oil lubes the moving parts.
You run it out of lube,bad things can happen.
My neighbors 200 had a problem with the oil system.
No lube got to the system and he didn't heed the warnings.
Now he needs a powerhead.

Wouldn't the motor stop running due to a lack of fuel (or more appropriately an overly lean mixture) long before the crankcase, bearings, etc. were starved of oil?

 

[99yam40]

Re: Carburetor bowl drain screw on 25 hp 2 stroke Yamaha?

when running a single carb motor until it dies due to lack of fuel is not that bad, but one with multi carbs will mean some carbs will run out before others due to the way they a plumbed up (lower carbs will get the last fuel/oil mix depending on if mixed or oil injected)and those cylinders are running with out or just lean on lube and fuel.
The parts in the crankcase on the 2 stroke depends on the oil and fuel mix coming through it to lube the crank, wrist pins, piston skirts, and bearings

Just my thoughts

 

[robert graham]

Re: Carburetor bowl drain screw on 25 hp 2 stroke Yamaha?

On 2 stroke/carbed motors there's only a few places that fuel/water/contamination can settle, in the fuel tank, in the fuel/water separator, motor mounted fuel filter and last and most importantly, in the carb float chambers....draining each carb periodically is much less trouble/expense than not doing it and dealing with plugged carb jets/lean fuel mixtures later....On the 4 stroke/fuel injected motors there's other components to deal with....

 

[jerryjerry05]

Re: Carburetor bowl drain screw on 25 hp 2 stroke Yamaha?

Most newer motors come with a filter to stop the crud to the carbs/injectors.
If you ever break one open they ain't the best.
I install a fine particle filter between the carb and the pump.
Most bigger Yams have a computer in the system that when the low oil happens it sends an alarm and it stops the engine from higher revs.
The neighbor ignored the alarm and ran it anyway.
That's where towing insurance comes in REAL handy.

 

[jspriddy]

Re: Carburetor bowl drain screw on 25 hp 2 stroke Yamaha?

On 2 stroke/carbed motors there's only a few places that fuel/water/contamination can settle, in the fuel tank, in the fuel/water separator, motor mounted fuel filter and last and most importantly, in the carb float chambers....draining each carb periodically is much less trouble/expense than not doing it and dealing with plugged carb jets/lean fuel mixtures later....On the 4 stroke/fuel injected motors there's other components to deal with....

On the 2 stroke, carburetor engines, can fuel settle in the fuel pump? If so, how would you drain it?

John

 

[robert graham]

Re: Carburetor bowl drain screw on 25 hp 2 stroke Yamaha?

I've never given any thought to fuel/water fouling in my fuel pump....on my C90 the pump is a super simple diaphragm type unit that rarely gives trouble other than the normal wear/hole in diaphragm issue....

 

[99yam40]

Re: Carburetor bowl drain screw on 25 hp 2 stroke Yamaha?

No good way to get all the fuel out of lines and pump without taking apart and blowing out.
I just make sure to keep running mine often to make sure nothing dries out and leaves residue.

I have found a thin layer of varnish (I guess)that hit the carb jets when I 1st got this used motor
and plugged a main jet and cause that cylinder to starve for fuel, looked like a small piece of plastic film.
I think it came from the fuel pump, but how really knows for sure

 

[jspriddy]

Re: Carburetor bowl drain screw on 25 hp 2 stroke Yamaha?

I've never given any thought to fuel/water fouling in my fuel pump....on my C90 the pump is a super simple diaphragm type unit that rarely gives trouble other than the normal wear/hole in diaphragm issue....

Guess I'll just let that go. Would assume that most would have either drained back through the filter when I drained it, or out the carb when it was drained.

John