Draining the carb of a Yamaha 2B 2HP outboard

[LiftyK]

After being rested for around eighteen months, my trusty Yamaha 2HP two stroke outboard motor burst into life after just a few pulls of the starter cord. That was a great result considering the fuel had been in the tank all that time. It gave another great performance two weeks later. I put it down to adding Sta-bil fuel stabiliser and running the float chamber dry after each use.

Chatting with friends, I learned that I should also be draining the carburettor as well as running the engine (float chamber) dry after use. Accordingly, after flushing the engine at home, I switched off the fuel cock and ran it dry. To access the float drain screw, I started to remove the engine cowl. Hang on a minute. To get the cowl off, the fuel cock needs to align with a slot in the case. In that position the fuel is on. So to access the carb, I need to open the fuel cock to get the cowl off and that refills the float chamber. So long as there is fuel in the main tank, the act of removing or replacing the cowl will always refill the float chamber.

My conclusion is that I can’t fully drain the float chamber unless the fuel tank is empty. Am I missing a trick?

 

[QBhoy]

I’d just keep doing what you’re doing. Understand the principle of it…but I’ve been doing just what you have for decades now with my old school small Yamaha engines. Never had an issue with them yet. Although I have been running super unleaded in the ones I’ve used most recently. Should you want to so it though. Surely you can either take the bottom cowling section off or if not…then the fuel valve off once the cover is off ?

 

[VicS]

I agree with QBhoy, although he does not realise that the cowl is left side and right side
You dont seem to have had a problem with just running it until "dry" therefore there is no need to fix what is not broken.

But if you insist could you cut away the cowl around the fuel cock so that one side of the cowl can be removed which ever position the cock is in. Alternatively can you cut access to the carb drain plug

 

[LiftyK]

Thank you both. As my ancient engine still looks as good as new, I will resist temptation to cut an access hole and instead continue my current practice of running dry and using fuel stabiliser.

 

[QBhoy]

I agree with QBhoy, although he does not realise that the cowl is left side and right side
You dont seem to have had a problem with just running it until "dry" therefore there is no need to fix what is not broken.

But if you insist could you cut away the cowl around the fuel cock so that one side of the cowl can be removed which ever position the cock is in. Alternatively can you cut access to the carb drain plug

Ah. Of course. Fair play. These wee things split each side, don’t they.

 

[Steve65]

After being rested for around eighteen months, my trusty Yamaha 2HP two stroke outboard motor burst into life after just a few pulls of the starter cord. That was a great result considering the fuel had been in the tank all that time. It gave another great performance two weeks later. I put it down to adding Sta-bil fuel stabiliser and running the float chamber dry after each use.

Chatting with friends, I learned that I should also be draining the carburettor as well as running the engine (float chamber) dry after use. Accordingly, after flushing the engine at home, I switched off the fuel cock and ran it dry. To access the float drain screw, I started to remove the engine cowl. Hang on a minute. To get the cowl off, the fuel cock needs to align with a slot in the case. In that position the fuel is on. So to access the carb, I need to open the fuel cock to get the cowl off and that refills the float chamber. So long as there is fuel in the main tank, the act of removing or replacing the cowl will always refill the float chamber.

My conclusion is that I can’t fully drain the float chamber unless the fuel tank is empty. Am I missing a trick?

The float bowl should have a drain at the bottom. If its a side drain buy a used bottom drain float bowl

 

[LiftyK]

The float bowl should have a drain at the bottom. If its a side drain buy a used bottom drain float bowl

Steve, there is a drain at the bottom. The problem is that the fuel cock has to be in the open position in order to refit the cowl. This of course defeats the whole point of draining the bowl.

 

[bignick]

Why don’t you run the engine with the cowl removed and “run it dry” by closing the fuel shut-off.
You can then open the float chamber drain to see how much fuel/oil mixture remains and understand whether you need to bother about it or not. I doubt there’s much to worry about after you’ve run it dry, since the bit you’re ”running dry” is the float chamber in the carb, which is the same bit that the drain screw empties.

 

[Bav32]

If you had the Suzuki equivalent, there is a cut out, about 12mm, in the cowlings just below the drain screws. Big enough to undo the drain screw without re moving the covers.
Suggest you might want consider doing a mod to yours and have an easier life.

 

[VicS]

If you had the Suzuki equivalent, there is a cut out, about 12mm, in the cowlings just below the drain screws. Big enough to undo the drain screw without re moving the covers.
Suggest you might want consider doing a mod to yours and have an easier life.

I suggested this in #3 but LiftyK prefers not to cut an access hole.

 

[KAM]

My 2b just runs. I never do anything to it for winter. The only maintenance it seems to need is to clean out the carb every few years when it gets silt in the float chamber. It sits in a cockpit locker 6 months over the winter. I only had one problem and that was early in it's life the water pump housing became corroded inside and the engine be a me very stiff to start. I got a repair kit which had stainless wear plates which seems to have extended the life enormously. Can't remember when I bought it but it must have run for 20 years at least after the repair. A lovely engine hardly needs a pull on the cord to start.