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Bike won't start hot

Discussion in 'Maintenance and Servicing' started by slideways, Feb 27, 2012.

  1. OK, so I've got a really strange problem with my bike.

    It won't start hot if its been sitting for about 10 mins or more, via the starter motor.

    It starts perfectly cold, regardless of weather, never an issue for the morning start.

    If I stop for petrol or some other reason, and the bike sits for about 10 mins, it won't start, it will just turn over and over and over....

    The really weird thing is.....it will start fine with a very short roll start ... ?

    Also it WILL start if you stall it and try to start it up right away.

    So I'm really confused, normally I would assume some sort of tuning problem, but the fact it roll starts with no issue has me confused... ?

    any ideas?

    99 Cb 600
    alternator, rectifier and battery only 1.5 years old.
    air filter only a couple months old
    spark plugs less than a year old.
    start motor sounds fine cold or hot
    bike runs totally normal cold or hot.

    I do all of the maintenance myself, someone please give me a place to start lol :)
  2. I know not much about bikes but it does sound for some reason you have fuel starvation? Others will jump on to confirm and correct my theory. sit tight..
  3. nah if it pop starts fine it's getting fuel.
    i'd say it's the battery being hot and not quite kicking hard enough to start (takes more power to start than once it's running)
  4. Sounds like time you checked the valve clearances.

    First check the battery is up at 12.8volts or above.
    I've a Yam 1000 that wont switch on the ignitor if the battery is below 12.4.
    Push strarts easy though because as you turn the motor you also turn the alternator.

    hope this helps, let us know how you go, for future reference.
  5. ok I'll try and check those things....

    I was thinking it might be the battery or starter motor not working well when hot, but it restarts if you stall and start again straight away...
  6. Sounds like it's running lean or you need your valve clearances done.
  7. I've come across this issue with very worn engines with low compression but 85,000 kms on a modern lump seems a bit early.