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Help 1990 Honda CBR250RR not running

Discussion in 'Honda 250cc In-line 4's' started by IDontLikeUsernames, Dec 24, 2018.

  1. jmw76

    jmw76 Well-Known Member

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    Location:
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    My Bike:
    Honda cbr250rr mc22 road + 1 track, Honda RC 162 tribute bike, Honda Spada Vt250, Honda CBR900RR
    Spark plugs can be really problematic on these little bikes.
    I have chased misfire problems for ages and eventually solved most issues with a new set of plugs.
    I have never had any real success cleaning the plugs.
    What is more, if your mixture is off then the plugs can get fouled pretty quickly and then they are junk.
    It is not unusual to have things apparently working, go for a ride and then find you can not get it started again.

    Make sure you have good clean fuel.
    Check the filter at the bottom of the tank. These can get blocked.
    Pull the carbs off. Clean all the jets out. Clean any dirt from the fuel bowls.
    Check to make sure the intake boots are not leaking.
    Check that the vacuum line to the fuel petcock is connected and working. Without vacuum fuel will not flow.
    Put brand new spark plugs in.
    You can use a multimeter or megger to check plug condition. If you measure anything other than infinity (open circuit) between the top of the plug lead connection and the plug body, then throw them out. The insulator nose gets contaminated easily and then they just give continual problems. Do not waste time trying to clean them.
    Check all of your plug leads. Remove the leads from the coils and measure from the connection inside the plug cap to the end of the lead (where it screwed into the coil). You should get about 5k ohm (with original copper plug leads). OPen circuit or really high resistance is a problem.

    Good luck.

    Peter.
     
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