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choke starting on a cbr250rr

Discussion in 'Technical and Troubleshooting Torque' started by bbyboy, Sep 14, 2008.

  1. i just went to have a look at a cbr250rr on saturday. he was like a mechanic selling for a client.

    for the people who dont live in sydney, it was one of the hottest day we had this year.

    when he started the bike up i notice he was using the choke. i questioned him why he used the choke. he answered if a bike is made with a choke its suppose to start with it, giving me the impression its suppose to start with the choke every time.

    i thought that you are only suppose to use the choke when you are having problems starting a bike e.g. cold morning, not enough fuel. ive also read Typhoon's thread on choke starting, he stated that a choke is there for a reason, use it properly. which to me only use the choke when the bike is having problems starting

    is the mech trying to hide something by choke starting it and trying to give me impression it starts first go? or is he right about choke starting the bike most of the time?
  2. I have an 88 cbr250. Must use choke during winter for first startup in morning. Not so much in summer unless bike hasn't been started for a week or so. This is normal for an older bike, I have new spark plugs, new battery and recently cleaned carbs, using the choke to start the bike hasnt affected the way it runs at all, it still runs like a charm, just like how I bought it 4 years ago.

    As for your mechanic, maybe he wanted to make sure it fired up first go for you. Maybe the bike hadn't been started for a while? I know it was warm in syd the other day but the temp still got pretty low in the middle of the night.

    You definately dont need to start with choke everytime. Only when engine needs some aid to fire up.

    I suggest you get the engine upto operating temp, hit the kill switch and try start it without the choke. If it struggles it may have fouled plugs, old battery or dirty carbies.
  3. he started it up the 2nd time without choking it. it started quickly and the engine sounded was clean. so i guess nothing hidden there

    ranjet, out of curiosity, if you dont mind me asking how many k's did u buy your bike at and at how much and whats how manu k's is it sitting at atm?
  4. Having had a both CBR250RR and FZR250 all I have to say choke = flooded engine. Never needed it...
  5. so being such a hot day, there shouldnt be any reason for him to choke start it unless there is something wrong? flooded engine is a simple fix right?
  6. As others have said, if it hadn't been started in a week or so the choke just guarantees it will start more easily.

    If you have concerns, go inspect it again and get him to start it without any choke. Its normal for a bike not to start with the first click if it hasn't been started for a week or so, its just that the battery has lost some of its charge over that time.
  7. A correctly tuned bike should need choke if it is completely cooled and the outside temp is up to around 25 deg.

    After that it shouldn't need choke. If it does it's probably running too lean in the idle circuit.

    If you can start it without choke when it's completely cold and the temp is below 20 then it's probably too rich in the idle circuit.
  8. More than likely if its a carb'd model, after a few days the float level has dropped due to evaporation, and the choke compensates for this and richen's the mixture up.
  9. He isn't hiding anything at all. Engines are designed to run optimally at running temperatures. When an engine is cold, it is difficult to atomize the fuel making it harder to ignite. Using a choke will supply the engine with more fuel/less air to overcome this problem until the engine warms.
    Choke is not usually required if the engine is warm, and on the first start of a warm to hot day due to the warmer air intake & higher fuel temp.
  10. +1

    "Hot" for you is not the same for your bike.

    I always use the choke with a cold (i.e. ambient temp) engine, but in warmer weather the bike will run without it a lot sooner.
  11. No worries,

    Bought my 88 cbr250r for $3000 with 58,000kms on the clock. Had the bike for just over 3 years and its now upto 72,000kms. I expect the bike to go for a lot longer too.

    Here's the thing about CBR250RR's. Odometer readings isnt a big concern as many have been wound back and in fact, they only go upto 100,000kms before starting back at 0 again. The condition of the bike both cosmetically and mechanically will determine the real amount of kms the bike has racked up in its long life. A well looked after and regularly serviced CBR250 will exceed the 100,000km mark with ease.
  12. I always try to start without choke on my RR. Generally if I manipulate the throttle correctly, it'll fire up in most conditions. Use a tiny bit of throttle, hold it at 3k immediately after starting. If the revs start to sag, don't increase throttle as its probably flooding.

    No go? Choke time. Just don't go gung-ho with the throttle.
  13. i only use the choke on my cbr250rr at 5am in the morning if it is icy cold, otherwise it always seems to start fine.
  14. i always use the choke on my cbr250, if i dont and start it, after about 10 seconds in will shut off, i have to hold the revs up until its warm then it idles a bit lumpy around 2k. Hows my bike running ?
  15. Your bike?
  16. correct! anyone know if its running shit or not ?
  17. Sounds to me the engine is about to give up the ghost and possibly blow up.
    I'd be selling it real cheap real quick. :shock:

    .. joking

    That 'lumpy' sound before it dies is probably overfuelling. Try this:
    Start engine .. as per normal with a little choke, and just as you hear her begin to flutter, rev the engine a few times whilst giving a little more choke to get the fast idle up, this will assist in getting rid of that unburnt fuel so the engine can play 'catch-up'. The engine should then idle quite high .. drop some choke to get her idling back below 2K. After a few min you should be able to shut the choke completely.
  18. o sorry, i just bought a bike and i thought you were the seller