300 runs bad under a load

EvanMellott · Oct 4, 2011

Just recently my 300 RC began to run bad under a load. I'm pretty sure that it is getting a steady flow of fuel. I'm thinking that there is something worn in the eletrical system. What do you think is happening? And whre do I get the parts to fix this?

rustyfarmall · Oct 4, 2011

Replace the spark plugs first with Autolite 388s or similar, and if that doesn't solve it, you probably have some fuel delivery issues.

Charlie M · Oct 4, 2011

I'd suggest changing points and condenser - my M runs bad when the points begin to go bad. Also what's your definition of running bad - is it skipping, no power etc. If the tune up doesn't work then based on symptoms there are possibilities.

El Toro · Oct 4, 2011

Pull the fuel at the carburetor and see if there's a full stream of gas from the tank. If that looks ok, your carburetor may need a good cleaning. The fitting on the carb where your gas line connects may have a screen behind the fitting that's full full of rust and dirt. If your carburetor has a main jet adjusting screw I would open it as this will enrich the fuel mixture. Hal

old · Oct 4, 2011

Does choking it help or hurt the problem??? If it helps you may have either a fuel problem or weak spark. Check to make sure you have a good blue/white spark that will jump a 1/4 inch gap. Also pull the drain plug out of the bottom of the carb and let the fuel flow for a few minutes. Catch the gas to make sure it does not have water and or dirt/rust in it then go from there to figure out how to fix the problem

Anonymous-0 · Oct 4, 2011

Reach up under the float bowl and back that power screw out a turn or so. See it it makes a difference.

rhtx55 · Oct 4, 2011

Turn the main jet on the carb GENTLY !!! until it is completely closed,
Back it out 5-1/2 turns & try it under load then. If it blows black smoke out of the muffler under load, turn this screw in 1/2 turn at a time, until it doesn't blow black smoke, that will be the "hard pull" setting.
If it will not blow any black smoke, at 5-1/2 turns out you have either a fuel supply problem as discussed above or a clogged main jet in the carb.

When doing light work, turn it in a turn & 1/2, or 3 to 4 turns out from closed or until it stops smoking under accelleration from half to full throttle, this should be close to the "light load" setting.

300 runs bad under a load

EvanMellott

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rustyfarmall

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Charlie M

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El Toro

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old

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Anonymous-0

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rhtx55

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