Re: Rough idle keeps coming back
Mike, carb could have a build up of sediment/dirt/corrosion inside.
I would remove the carb top & check it out. Unlike brand H [ & clones ], you do not need any gaskets if you are careful. These carbs are simple in design, sophisticated in operation.
I will walk you through it. Take some pics first of the linkages etc so that you can re-install properly.
- remove fast idle/choke linkage circlips
- remove air cleaner stud
- remove acc pump linkage circlip, note which hole is used in the pump arm.
- loosen metering rod piston cover screws 2 turns. Swivel covers to one side & remove met rod assemblies and the springs.
- if using rubber fuel line to the carb, you can probably leave the line connected to the carb.
- remove screws around carb top [ airhorn ] .
- lift airhorn straight up, may need a light tap to loosen it, make sure gasket comes away with the airhorn. If the gasket sticks to the body anywhere, pry it away gently with a knife.
- turn airhorn over & lay it on the engine.
Things to check:
- are the float bowls clean, check jets for blockages. Idle jets are fed from primary main jets.
- check that floats are set at 7/16". With needle & seat wear, this can reduce & give a rich mixture.
- remove the float pivot pins, one at a time, then remove the float needle, check the rubber tip for wear/dirt. If they are worn, they should be replaced, can be bought separate from a repair kit.
- remove two screws holding acc pump nozzle; underneath in the pump passage, you should see the top of a brass needle. It should be DOWN.
- check that all the booster mounting screws are tight.
If all of the above checks out, it gets to really obscure reasons for the problem. Has the carb base gasket deteriorated; is there an air leak there?