RD carb woes

[stanley]

I have an RD14 and15 I’m trying to get ready to run on boat.Both have rebuilt carbs and ignition.The 14 has rebuilt power head.Neither is responsive to high speed circuit.They will start with high speed needle closed and low speed open two turns.I’m assuming it’s a problem in the high speed circuit,but hard to believe they share that problem.Is there anything else I should check.

[frankr]

1. It might start at those settings, but will it actually run at high speed with those settings?

2. Why are you starting it with those settings anyway? Try with LS 1-1/2 turns and HS 3/4 turn. That will be too rich and have to be adjusted from there.

[garry-in-michigan]

Those models did not use the 0203984 gasket on he high speed nozzle like the smaller motors. It was thought that the amount of fuel leaking around the needle valve could be fixed by screwing in the high speed needle valve a bit. Of course this gasket is absolutely essential on fixed jet carburetors. Many add it to these higher horse power motors to make the high speed adjustment more responsive.Another problem of which you are probably aware is the floats where sealed with shellac. The alcohol in todays fuels dissolves this and allows the cork to absorb fuel. This has the effect of raising the fuel level in the float bowl causing the outboard to run rich. If I find a good float in this condition I set it out in the Florida sun which soon bakes out the fuel and then seal it with a light coat of Super Glue. A less han perfect float is best replaced. . .

• This reply was modified 5 years ago by garry-in-michigan.

[stanley]

I’m running them at those settings because that’s the only setting they will run at.I have the low speed set at 1 1/2 out and high speed 3/4.Starts and back fires and runs rough.I open low speed another turn,it quits backfiring,but still runs rough.Nothing I do with High speed while it’s running has any effect.Both motors act the same.I am using the same pressure tank for both.If there was an issue with the tank,would that explain it.

• This reply was modified 5 years ago by stanley.

[frankr]

Running the pressure tank, right? I don’t see how that could be causing any problem as long as it is supplying enough gas to the motor to run.

[stanley]

Yes,running a pressure tank.I just thought the tank might be the problem since it’s the one thing both motors have in common.(Besides me).

[outbdnut2]

When you rebuilt the carbs, did you use an aftermarket kit? If you did, you did not get a new float, as Garry mentioned. You can buy an OEM kit or just the float at http://www.marineengine.com

I’ve found the bowl gasket on some aftermarket carb kits is too thick to not use the high speed nozzle gasket Garry mentioned – you may have to cut that nozzle gasket a bit thinner to make everything fit together right.
Dave

[stanley]

Yes,I did use aftermarket kits.The floats in both carbs were in good shape,but per your suggestion I’ll put new ones in and add a thin nozzle gasket,while I’m at it.

[olcah]

You may be leaking air thru the needles. Try adding more packing. (My first go to cure for unresponsive carb needles.)

[dan-in-tn]

Better yet buy the #382363 (18-7210) float from the current TR carburetors. It is the new Nybril material and requires no coating.
Slight modification allows it to work in place of the old style cork float.

Dan in TN

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