Welcome to Netrider ... Connecting Riders!

Interested in talking motorbikes with a terrific community of riders?
Signup (it's quick and free) to join the discussions and access the full suite of tools and information that Netrider has to offer.

bike stalling when reving to quickly

Discussion in 'Technical and Troubleshooting Torque' at netrider.net.au started by OscarA, Aug 2, 2009.

  1. Not exactly sure how to explain this but here goes.
    I have a FZX250 Zeal that seems to run fine with no real issues except one.
    If I rev the bike to quickly she stalls, if I slow it down a little she'll splutter then rev up normally and when I gently (not to gently) rev it all is fine.
    I've had the problem from day one and initially thought it could be stale fuel as the owner told me it hadn't been ridden much and the fuel was probably a month or two old.
    I also notice that when I practice my slow speed maneuvering I'll give her a little throttle with little response so I'll give it a little more and the bike would lunge forward.
    I'm still learning so figured all I needed was practice but now I'm thinking perhaps there's more to it.
    I use unleaded fuel, not sure what else I can say.
    Any advise would be great, thanks.
    Forgot to mention when warn it's a little better but she'll still stall if I rev it to quick.

    Just re-read my post and it's a little confusing, when I say rev the bike gently and all is well I mean if I slowly roll the throttle on to full throttle she behaves and wont stall.
  2. Sounds like it could be flooding mate. If you rev it in between what you say is too fast and just right, does it splutter, and then come good as the revs go higher? If the answer is yes, then that is a good sign of flooding. Check your choke cable isn't caught, and slides in and out freely, this can be one cause.

    Is the bike due for a service?

    A cheap first check would be new spark plugs all around. As plugs get older, it can be harder for them to deliver ad good spark at lower rpm in some types of ignition setups, and depending on the condition of your stator. A loose spark plug can also have the same effect. When you put them back in, they have a squash ring on them, so tight is tight enough. When it starts to get hard to turn, don't go further than that or you risk stripping it out.

    There is also a chance that it could actually just be leaning out past the point of running smoothly, and to that extent, check/replace the inline fuel filter if it has one. You mentioned it sat around with old fuel in it, so this could easily be a problem. If you can get the tank off without too much trouble, also consider emptying it completely, and rinsing it with a little fresh fuel a few times, then putting it back together with a fresh tank.

    If it is a carburetor engine, you may need to have them balanced, or even have them checked as you may have some gunk in them.

    Good luck with it, and post up if you work out anymore symptoms that some of the more knowledgeable chaps around here may be able to help you with.
  3. Thanks VTRAffair, that's exactly what it does, it'll splutter then come good.

    According to the bloke I bought it of it doesn't but I'm a bit sceptical about that.
    I've had the bike for about 3 months and only done 1200kms and prior to me buying it the bike was service 6 mths earlier and he claimed it was rarely ridden. I changed the oil straight away and it was black, I don't know how quickly oil goes black but it looked old and quite thin so I'm guessing it probably wasn't serviced as recent as he claimed or it was ridden a lot more than seldom.

    The previous owner did give me a spare fuel filter so I'll change it and I'll also check/change the sparks.

    Thanks for the advise.
    The bike does run well but with this issue sorted perhaps my slow speed maneuvering will improve and I wont stall at lights anymore :oops: