Draining The Carb After Every Ride

[Chief]

Someone recently mentioned that they close the fuel valve and run the bike until the carb runs dry after they ride. Can't remember who but thanks, I like the idea and started doing it for 2 reasons; I would rather not have fuel sitting in the carb for days at a time or more, and it makes pre-ride jetting easier by eliminating the chore of having to catch fuel when I open the carb. (whatever I miss washes the chain and sprocket)

Today I noticed small particles settled in the bottom of the float bowl drain plug, also one or two small water droplets. If I didn't drain the carb, this stuff would usually just come gushing out and I would miss it.

When I finished up and turned the fuel valve on, gas started to leak out of the overflow hose. This never happened before. It stopped once I kicked the engine over a few times. I guess the float valve stuck open from the last time I shut the bike down.

What is your opinion/experience on running the carb dry? I believe it overflowed because I ran it dry.

What about pros and cons? I know the lean surge when the carb runs dry isn't good, but how bad is it? I take care to only rev it enough to run all the gas out.

Would running it dry tend to suck any floating particles out of the carb & into the cylinder? I think that's where they end up anyway.

I am going to figure out why there is dirt in there.

Thanks--Joe Chief

 

[yardpro]

i would think that running the carb dry would cause the engine to run lean just as the fuel supply was depleted. I feel that that would be detrimental to the engine, causing excessive ring wear, etc.

 

[MX-727]

It may have been me. I've cleaned out some pretty gunked up carbs, but you'd have to leave the fuel in there for a long time for that to happen. I usually shut it down right when it starts surging. I don't feel that this causes any damage at the RPMs involved.

It sounds like the dirt caused the float to stick.

 

[spanky250]

I usually drain my float bowl after a ride if my bike is going to sit for more than a week or two. I just open the drain on the bottom of the bowl. Having month-old gas in your float bowl can make for difficult starting sometimes.

 

[MikeT]

Originally posted by spanky250
I usually drain my float bowl after a ride if my bike is going to sit for more than a week or two. I just open the drain on the bottom of the bowl. Having month-old gas in your float bowl can make for difficult starting sometimes.

Do you also drain your tank? The fuel inthere would age the same right? I have been buying less and less gas to try to end up with nothing at the end of my ride. What do you do with the fuel in your tank?

 

[dadshillnut]

Draining carb

I am certainly no expert but I do know that all the major outboard boat motor manufacturers stopped recommending that several years ago because of concerns over engine wear. I know they are not the same but late model motorcycles and outboards are both high performance, high compression 2 strokes

 

[RM_guy]

Joe,
If you are worried about “bad” gas in the carb when you start the engine, before you kick over the engine, turn on the gas and lean the bike to the side a few times. Gas will flow out of the over flow tube. This will flush out and old gas (or water since it is heavier than gas and will sink to the lowest point) and give you a fresh charge of fuel.

I have never run the carb dry because I worry about running the engine lean (with no oil) for any period of time.

 

[Chief]

Thanks To You All. BTW, HAPPY NEW YEAR!!!

 

[BrianW]

Way back when (late 70's) I used to turn off the fuel and run my '76? RM80 dry every time I rode it - and that was every day or every other day. Had it for 3.5 years and never had a problem. Of course I also ran BelRay MC-1+ at 50:1 which people are now saying is bad, but that little bike started and ran like a champ - one or two kicks is all it took. Never did ANY engine work to it and only changed the trans fluid about once a year!

What I do now is run the bike about 1/2 the time it takes to run the carb dry(~1.5 minutes). I figure this is a good compromise since it doesn't run the engine dry and lean.

 

[needa250]

i would assume its ok bec the engine cannot be flooded while not running. i wouldnt worry about the engine running lean bec i would not run the engine till its out of gas, i would drain it by loosneing the screw on the bottom of the carb. and to start i would prime the carb.

 

[DENNY]

Chief bad gas isn't why you turn off the fuel. It's to eliminate the chance of flooding the engine. Let me tell you one of my bad experiences. In the mid 80's I loaded my KTM on to my truck after riding an Enduro. For sum reason I forgot to shut off the fuel. When I got home I noticed the fuel was on and while it was strapped down in my truck I gave it a kick. The kick starter would not move and I removed the spark plug. Well the cylinder was full of raw fuel and when I kicked the bike over it caught on fire. That mistake cost me alot of money and since then I have always turned off my gas. This technic has been used on 3 bikes over the last 15 years without a problem.

 

[RM_guy]

:think Good advice Denny but he was referring to running the carb dry after shutting off the gas.

The problem you had was probably due to a stuck or leaking float valve and the gas siphoned into the crankcase. Shutting off the gas and not running the carb dry will would have help with that.

I always turn my gas off even if I’m stopped for a few minutes. My problem is that I forget to turn it back on and I run out of gas at the most inopportune time :eek:

 

[WoodsRider]

As mentioned above, running the carburetor dry means you are not providing oil, for lubrication, to the bearings and rings on a two-stroke engine. You will not have this problem with a four-stroke engine though.

Personally I prefer to manually drain the gas from the carburetor if the bike is going to be sitting for more than a month. During normal weekly use I simply lean the bike over to make sure that gas is flowing to the carburetor prior to starting.

I’m no fuel expert, but gas in the tank and gas in the float bowl should go “stale” at the same time. Over time gasoline will turn to a varnish creating obstructions in the carburetor jets and passageways. Once this happens you need to disassemble the carburetor and clean out all the passages and jets.

 

[spanky250]

Part of the reason I drain the float bowl is because dirt gets into your fuel while riding, and settles in the bottom of the float bowl. Draining it removes this.

I try not to buy more fuel than I will use for a ride, usually 3 or 4 gallons. Any extra that sits for more than a month is relegated to the weedeater and lawnmower. I rarely have to buy gas for either of them ;) .

 

[stan921]

I believe that if you add little Stabil or Marvel mystery oil to your gas, it won't go bad or turn to varnish. A friend of mine uses both in his gas. His KTM 520 started on the third kick after sitting for over a year!

 

[yardpro]

stan921
you should be very careful of using old gas with two strokes. While stabil will keep the gas itself from going bad, it will not keep the oil from separating from the gas. since the oil is heavier, it will settle to the bottom. when you pour it in you could be dumping in straight gas. in the tank, the oil would settle to the bottom. it you have an enduro with a reserve, it is very likely that the oil will settle below the bickup tube. same scenario- straight gas.

 

[Brian]

I've always done this(run the carb dry) with just a few seconds of surging, then it would die. Now, after toying with the carb a little, doing so causes it to idle way up when doing this. I took off the carb, then put it back on to make sure there weren't any air leaks. I'm stumped :think:

 

[Chief]

Stan,

I guess something changed. If everything else is ok, I would kill it once you lose control of the idle. I'm just telling you what I would do. The bowl is pretty dry once I start to surge anyway. If you have a real problem, it will eventually present itself in other ways. (unfortunately) Since it happened after you adjusted your carb, you would have to chalk it up to that as a cause. My bike does the surge thing, high idle whenever I let it run dry, so I guess it's a matter of adjustment.

On a similar note, I have now gotten into the habit of shutting off the fuel and running it just til it surges, unless I'm planning on changing a jet, then I let it run dry.

Ride On!!!

Joe Chief