Honda PA50II carb problems

I am having trouble starting my Honda PA50II Hobbit. I am pretty sure its the carburetor. I took out the air filter and sprayed a bunch of starting fluid into the intake. It pops a few times but then dies. Gas is getting into the float bowl of the carb. I know because I can drain the bottom of the bowl. I took off the carb and cleaned it REALLY well with a spray can of carb cleaner. But nothing.

Help!! I dont know what to do. Do I need a new jet or what?

Re: Honda PA50II carb problems

Don Pflueger /

take the carb back off and run a piece of wire thru every hole you can find in its body and all its parts. make sure that when you put it back together that you have the bowl on the right way and the float moves correctly. also check compression. you want to see 120 lbs or higher. drop the exhaust and make sure the port is clean as well as the exhaust itself.

Re: Honda PA50II carb problems

I assume this bike never could get started and nothing you did recently could have caused this change in behavior? Or perhaps it has been getting worse over the course of time..

Sometimes spraying with carb cleaner isn't enough.. there are tiny hidden passages and it takes strong compressed air and soaking in solvent to blow them out.

Remove the idle speed screw. (it's the one with a spring behind it and it's tip makes contact with the throttle linkage at the carb).

Below / under that idle speed screw is another screw. You can see it's head but cannot remove it until the idle speed screw is out of the way. Remove this other screw and look inside the hole.. There is a really tiny jet pressed into the bottom of that hole.

That jet delivers air to the "emulsion tube" (the brass tube stuck up above the main jet). This jet and passage pre-mixes air with the fuel as fuel comes up the main jet and into the tube.

The emulsion tube is another often neglected thing that a thorough cleaning should include. It should be removed and cleaned. It's just lightly pressed into the cavity above the main jet. Push the tip of it down with a pencil to get it started on it's way out (You can see it's tip sticking up into the venturi). Air pressure can blow it all the way out or pound the carb into a folded towel or another protective padding until it drops out.

If you're positive the carb is truely clean, then look for loose nuts and bolts especially around the carb intake manifold. Loose head bolts are another thing although they dont seem to loosen by themselves on this particular engine..

Since it fires up with starter fluid, it does seem to be a fuel delivery problem. The only other likely thing would be extremely low compression.

Re: Honda PA50II carb problems

Brian Tam /
btam OP

Thanks joew for the advice. I have since completely stripped the carb, jet, emulsion tube, any screw I could find. I put a wire through everything and soaked it in carb cleaner. Still nothing, not even a pop. Only when I put in starter fluid did it rev up for a second, but soon died again. I dont know what to say.

Im thinking of just buying a new carb. What aftermarket carbs can you suggest? What other mopeds have carbs that will fit my PA50.

Thanks anyway guys.

Re: Honda PA50II carb problems

Check that the float bowl on the carb is on correctly..ie, drain thing to the right...it can be put on wrong..180 deg out ...

Re: Honda PA50II carb problems

Don Pflueger /

after doing all that, i would check fuel flow from the tank, make sure there are no air leaks around the intake and cylinder base gasket, and test compression. you may have a bad crankseal.

Re: Honda PA50II carb problems

The PA50 has a reed valve under the carb. Did you check to make sure the reed valve is opening and not stick shut by old varnish?

PITA to take it off again I know so start at the tank and petcock and make sure you have fuel flow into the carb. I think the petcock has a filter at the bottom that can be removed and cleaned.

You can open the drain on the float bowl to see if it is filling up.

If you have fuel flow, then you'll have to remove the carb again to check the reed valve

Success!!

Brian Tam /
btam OP

Success! It runs, kind of.....

Taking off the carb (for the 4th time this weekend) and soaking it in Mineral Spirits must have done the trick. Zippy, the reed valve was working, and was clean. I did go through the entire carb with a wire and make sure all the passages are clear. All the checks and the soak must have done it.

However, now it doesnt idle. And it only runs when I sit on the seat. I stand up on the pedals and it dies, then I sit down and it revs. This may be a wiring short, but is there a possibility there is a safety switch in the seat?? I havent yet had a chance to go through the wiring, and this may solve the problem.

Thanks for all the help in advance fellas.

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