Cleaning Carbs ?

[bigdog]

I was cleaning the 4 carburetors on my 2000 Johnson 90 HP 2-storke today, with a spray carb cleaner, shooting the spray directly into each carb throat.

I noticed when I sprayed into the Port side 2 carbs (upper & lower) the engine started to rev a lot, I mean a lot !
And when I sprayed the Starboard 2 carbs (upper & lower), the RPM's started to drop significantly, to the point where the the engine almost stalled and died, until I stopped spraying the carb cleaner.

Honestly......
Am I loosing it, or is there some reaction phenomenon/behavior occurring here, or is this normal, that I am unaware about?

Thanks,
Bigdog

[HomeWood]

Not sure why one side revs and the other bogs, but I don't see that being an effective way to clean carbs. That's how to fog an engine for storage. Spraying carb cleaner directly into the intake doesn't clean the jets or crud in the bowls. If anything, it will clean off some of the carbon in the combustion chambers. Plus, the carb cleaner is a solvent and any oil or lubrication is being washed away from the cylinder walls and that's bad.

To properly clean a carb, it needs to be disassembled. Then all the jets and fuel passages need to be sprayed out with carb cleaner and lightly scrubbed with a wire brush. That's the basics. I've cleaned more carbs than I can count.

The best way to keep carbs clean is with fuel stabilizer and a dose of Sea-Foam now and then right into the fuel tank.

If the engine is running fine and normal, there is no need to clean the carbs or spray carb cleaner into the intakes just for good measure or peace of mind.

A great way to get an idea of how your 2 stroke is running is to look at the plugs. White color = lean condition (very bad). Black/oily = rich condition. The ideal color for a 2 stroke plug is a brown or tanish color.

Backfiring is also a sympton of a dirty carb or carbs.

[NHBUOY]

I think you have a vacuum leak or gasket seal problem.

[HomeWood]

Originally Posted by NHBUOY

I think you have a vacuum leak or gasket seal problem.

A test for that is to seal the engine back up with the air cleaners or covers over the carbs. With the engine at idle, spray starting fluid or carb cleaner at the base gaskets of the carbs where they meet the engine block. If the rpm changes, you have a bad gasket and need to change it. A bad crankshaft seal in a 2 stroke will have a similar affect. This causes a lean condition (too much air) and can do major engine damage.