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Help needed, bike won't start.

Discussion in 'Technical and Troubleshooting Torque' started by dm_obrien, Jun 6, 2006.

  1. Hey all,
    My honda CB250 won't start. I've tried everything I can think of, and that has been suggested in previous similar posts (short of cleaning the carbs). I have limited mechanical knowlege and skills.

    Background: Bought a 1992 Honda CB 250 few months back and didn't get round to doing q-ride til recently. The bike sat with a tank full of petrol (yeah i know, whoops) without being ridden. The battery was also dodgy.

    What I did: Replaced the battery with a new one (charged it too), drained the fuel from the tank and bike and replaced with new fuel, took out the spark plugs and they looked fine.

    What happens: It doesn't start up. The electric start sounds fine, but it just doesn't start. I am very stumped.

    Is it time to take it to a mechanic? Do the carbs need cleaning and can I do this myself? Help.

    Thanks in advance for your help,
  2. It needs fuel, air and electrickery to start, as well as some way of compressing them.

    Air is not usually a big problem, but it might be an idea to check tthat the air filter is not clogged.

    Fuel: After you try to start it, and it has been spinning for a bit without catching, pull out a spark plug and see if it is a bit damp with fuel. If not, then there is probably no fuel getting to the combustion chamber.

    Remove a spark plug, connect it to its lead, and rest it against the fins if the cylinder or some convenient part of the motor. Do not hold it there with your hand. Turn on the ignition and press the starter and see if there is a spark. If not, then the problem is electrical.

    If you have fuel and a spark, then it is likely that either the fuel is getting there in the wrong amount or the spark is too weak or happening at the wrong time.

    If the bike was running OK when parked, then it is unlikely toi have developed a compression problem in the meantime.

    When you have worked out whether it is electricity or fuel that is the problem, get back to us and someone will help with the next stage of diagnosis.
  3. The carbs will probably need cleaning, you can drain them and clean them, but it is normally more work
    Start by getting some carb clean in a spray can, have everything off the bike so you can see the intakes and the fuel lines going into the carbs, and spray the crap out of it, tip as much fuel out of the fuel lines as possible and spray it in there.
    Try starting it with a remote fuel supply, and then spray the crap out of it again, either while its started or as its pulling air through to try and start.
    If that doesnt do it, you will probably have to strip the carbs of the bike and solvent wash them and let them sit it in for a while, depending on how your carbs are, this could be easy or hard.
    If it gets to that stage, there are carb cleaning faqs on the net if you search google.
  4. Basic test equipment for the mechanically challenged. Do as moike suggests and check if you have a spark. If you do, go to Supercheap Auto and buy a can on 'Start Ya Bastard', and while cranking the motor spray some into the airbox. If it fires and then dies, the ignition system is ok and the fuel system is the problem. If it fires and runs, keep it running and this may well clean everything else. If it doesn't fire at all it's the ignition system.
  5. Ok, I pulled off the spark plug, reattached the wire, rested it on the fins, turned the ignition and pressed the starter. I didn't see any spark, on either sparkplug. Do I need to have the end of the plug actually touching a metal part of the engine? or if its working will I see sparks anyway?

    When I pulled them out, the end was dry, i.e no petrol. The electric start did sound like it was doing something.


    also tried sticking a screwdriver up the connection wire to the spark plug, with no result (to check if the sparkplugs weren't at fault) . I'm guessing there is something wrong with my electrikery?