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New guy with some (Fuel?) issues

Discussion in 'The Garage' started by Woutair, Jul 9, 2019.

  1. Woutair

    Woutair XS400 Member

    Hello chaps,

    I have a bit of weird issue with my '84 Maxim. At highway speed (60-70mph) it will occasionally stutter. It is not a consistent fault as some days it runs fine, and some days it has this random stutter. Also, at low rpm driving around town it occasionally seems hesitant to accelerate before randomly surging forward sometimes as if nothing were wrong. This usually happens after I have done a few miles and the engine is warm. My guess is a bad ignition coil, but I am not sure. Anyone have any idea what could be up with it?

  2. I would venture to say it's carb problems. The main jet controls the fuel when going full throttle. If it's dirty (or too small based on mods) it'll stumble . Similarly the pilot jet is what will determine how smooth your bike runs at take off. Have you tried to thoroughly clean those bad boys ? Even if you think your jets are clean, if your tank it dirty, it could have reclogged them. Imo start with a clean tank and clean jets. If you recently changed the air filters or exhaust you might need bigger jets.
  3. Woutair

    Woutair XS400 Member

    Little update

    I guess you're right about it being something with the fuel system. I had a look at the carbs last week and they seem fine. However, I turned the fuel petcock to "PRI" rather than "On" and the problem seems to have gone away. It seems to be a vacuum related problem. Guess I will have to rebuild or replace the petcock. Does anyone have a suggestion for a replacement part or a way to properly rebuild it? Will be running it on "PRI" till then I guess. Some bikes bypass the fuelfilter element in the tank on PRI, is this also the case in the maxim's? If so it might be a dirty filter, although I recently cleaned it.

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