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1979 xr185 running problem


Joexr185

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Hows it going guys new to the forum, I am having some running issues with my dads old bike that we just recently go running after sitting for a while. (Sorry for the long story) We cleaned the carb and tank out, put in fresh gas and it fired right up ran for like a minute revved up on its own, then stopped running. We figured out the gas valve was starving it of fuel. After fixing the valve we let the bike warm up tuned the carb a little took it for a ride to fine tune it and the mixture screw was missing. After putting another mixture screw we took it for a ride, where the bike is breaking up/bogging at low rpms, after getting past the problem the power will come in fast then at higher rpms it will do the same thing it is doing at low rpms (will do this in any gear). Would anybody have an idea on what would be causing the bike to behave like this, any input would be gratefully appreciated.

Joe

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Thank you for the response, we cleaned the carburetor really good we made sure all passages were clear. Corrosion was minimal but there was dirt in there and it was blocking the small holes in the jets, they were all cleaned as well as all the passages if they were important or not. When we found the dirt in the carb we cleaned the tank and got all the old gas out and got all the dirt out also. Is it possible the jetting is off or the valves need to be adjusted, the motor sounds extremely healthy at idle to me, no excessive ticking (just the little normal honda tick) no clatter that I can hear. I can pull the carb off again and clean it to see if any of the passages are clogged when I can get to it.

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Clean the carb again. Remove all of the jets and use aerosol carb cleaner on all passages and holes, then blow dry with air. Sight all jets and passages against light, I use an LED flashlight.  There are 2 very small passages to the throat of the carb that can foul; one is above the pilot jet (which is pressed in) and the other is above the mixture screw. The mixture screw requires a spring, washer,  and O ring in that order (O ring on last).  When removing the mixture screw the O ring often sticks inside the carb body.

Proper jetting for a 79 XR185 is:
Carb model PD31A
115 main
Needle clip 4th
Mixture screw initial setting 2 1/4 turns out

 

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Carbs wear out but the wear is not discernible to the naked eye as they say.

If the bike has miles it is likely that the needle and needle jet will need replacing.

The symptoms you describe sound like rich running from a worn needle/needle jet.

I expect you can buy a reco. kit.

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You can try lowering the needle one clip position and see if that helps compensate for the wear. You should verify jetting and float level are correct.
Float level should be at the parting line of the float bowl to carb body, attach a short length of clear vinyl hose to the float bowl drain and position it along the side of the carb aligned with the center line of the slide. Level the bike fore/aft and side to side, open the float bowl drain, and the gas should rise to the bottom edge of the carb body. The proper height is when the bottom of the gas crescent in the hose is at the lower edge of the carb body.

Needle and needle jets are no longer avail from Honda except for the 98+ CA XR200 models.  The XR200/R needles should be the same as the XR185, the mark on the needle should be F2351E, the 98+ CA needle will be different but should work. And the Honda needle jet kit includes the needle and needle jet, so at least that will provide a new needle jet and a possible new needle.

 

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