500 (Classic) Idle problem

Tirr · Jan 4, 2017

Hi hope someone can help.My Fiat motor has just been overhauld with a new carb.In the beginning it ran pretty well and 2 weeks later it stop idling and dies on me when i engage the clutch.i replaced the plugs then readjust the points and timing but still.....When riding its perfect...Help

Toshi 975 · Jan 4, 2017

I would check the idle mixture screw then make sure that the carb is sealing properly at the base or even loose. If that is ok I would check the valve clearances / tappets. When you say "new carb" is it one of the modern repro ones? I have heard recently that there have been problems with them and one 500 specialist saying that you are better off with a good used or rebuilt original carb.

gordinir8 · Jan 4, 2017

I agree with all of the above but also check carburetor throttle setting screw, ''the one with the spring''

jjacob · Jan 4, 2017

Make sure that the choke cable turns the choke piston off when you push the choke lever back down. Make sure the nuts that hold the carburetor to the intake manifold have not become loose. If you do not have a fuel filter installed, check the small screen filter in the carburetor, and maybe the screen filter in the fuel pump.
John

Tirr · Jan 5, 2017

Toshi 975 said:
I would check the idle mixture screw then make sure that the carb is sealing properly at the base or even loose. If that is ok I would check the valve clearances / tappets. When you say "new carb" is it one of the modern repro ones? I have heard recently that there have been problems with them and one 500 specialist saying that you are better off with a good used or rebuilt original carb.

Hi Toshi thanks for the advice yes it is a new repo carb I did check the choke cable and replaced the fuel filter and cleaned the idle jet and walla now it runs like a new one.Thanks for your time

Tirr · Jan 5, 2017

jjacob said:
Make sure that the choke cable turns the choke piston off when you push the choke lever back down. Make sure the nuts that hold the carburetor to the intake manifold have not become loose. If you do not have a fuel filter installed, check the small screen filter in the carburetor, and maybe the screen filter in the fuel pump.
John

Thanks problem solved and dont ask me exactly which one was the ONE.Did the choke ,new filter and cleaned the idle jet. Thanks engine like new

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