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.

Stalling, Not Starting, Strange Idling and No Power?

Discussion in 'Technical and Troubleshooting Torque' started by Boredom inc., Aug 17, 2009.

  1. Hi,

    I bought my first bike a couple of weeks ago. A second hand ZXR-250A '88, although somehow it has the ZXR-250C farrings on it. Anyway it ran perfectly the first week I had it, it had had a minor service the day before I picked it up.

    Since then things have been getting progressively worse. The bike usually doesn't start and I have to roll start it. I can hear the motor turning over and I don't think it's the battery because there are a few other problems. Today on my way home I pulled up at the lights it stalled about 6 or 7 times, and I had to take it off the side of the road and roll start it a couple of times. Even roll starting the bike is difficult, the bike starts but occasionally just dies immediately. Sometimes I can keep it revving but as soon as I let it idle it will stop.

    The whole way home I was constantly adjusting the choke trying to get something that worked but I noticed that whilst I had the same choke setting the RPM whilst idling would be different at each set of lights, 6000, 4000, 1500. It wasn't consistently changing either like the bike was heating up or anything (it was warm as the ride home was a decent distance).

    The strangest issue I've had happen, which happened briefly today and has happened twice in the past is that I go to take off and the bike has absolutely no power. Today I was in first gear and it just wouldn't get above 2500 RPM. The other time I remember what happened, I pulled out of a side street and got up to third but then suddenly no power. Going down to second, and then first had no impact I had to pull over.

    None of these problems are fuel related as I haven't even had to go on to reserve. Also, I filled up yesterday and problems started occurring when I'd done less than 40 kms.

    I don't know much about engines in detail but to me it seems like something is wrong in the mix. The bike does need tuning as idling isn't totally steady, it's not too bad though. Anyway it almost seems like the intake valves are getting caught open, is that even possible?. Or, too much air is being put in, which might explain why I have to roll start.

    I'm going to take the bike around to my brothers in the next day or two and will strip the bike down and pull apart the engine. Does anybody have ideas as to what we should be looking for? Are these common symptoms of a particular problem?

  2. Try opening the filler cap when it starts to die. I have heard these symptoms before and it turned out to be a blocked vent in the tank. Vacuum was preventing the fuel from flowing.
  3. I didn't think of that at all. I'll give it a go tomorrow and report back.

  4. Boredom Inc said:
    Just because you have a full tank of fuel doesn't mean the problem isn't a fuel problem. Fuel problems can be caused by:
    dirty fuel
    blocked fuel filters
    kinked/blocked fuel lines
    blocked carby jets
    air locks (hence the suggestion already made to loosen filler cap)
    carbies out of tune
    dirty air filter
    sticking choke
    and probably a few more I can't think of off the top of my head.

    Then there are the non-fuel issues.

    Unless you have some mates who are mechanically savvy, get some professional advice. If the bike was just serviced why not take it back to them and see what they say. If what they say is expensive, get a second opinion.
  5. Sorry by fuel issue I meant I didn't want people saying are you running low on fuel. Most of those things are fuel related but are mechanical, that's actually the sort of thing I was expecting to be wrong.

    EDIT: My brother has a decent idea and my step brother and uncle are both mechanics so I've got some good help available.
  6. I assume you know that's not a permanent solution - you shouldn't be using the choke at all once the bike's going.

    I can't give you any specific advice, but engines need three things to run; electricity, air and fuel, so your problem almost certainly lies in one of those categories. From the sounds of things, I'd hazard a guess that it's a fuel issue, but unfortunately I can't be any more helpful than that. I also second the above opinion that unless your mates know exactly what they're doing, spend the cash to get someone to diagnose the problem and fix it properly - once and for all. And if they don't, you have some recourse, which you don't if you do a home job.
  7. Yeah I know using the choke is not a real solution, and probably not good for the bike. I needed to get the bike home.

    Sorry if I'm a bit vague but what part of the engine requires electricity? Or are referring to the starter motor?

    It won't really be a home job. My uncle has worked as a mechanic his whole life (when he wasn't a motorbike racer) so I assume he's qualified. Plus I personally would like to supervise so I can get an understanding of things myself.
  8. Pretty lucky to have someone like that to go to with your problems, I'd kill for that kind of contact. The spark plugs are what require electricity to ignite the air/fuel mixture.
  9. Dah, completely forgot about the spark plugs. You won't get far without them unless you've got a diesel engine ;)

    I'm at uni at the moment. I still had to roll start my bike but I rode with the choke off and didn't have any problems stalling and the bike idled fairly consistently. I tried starting the bike with the cap open but that didn't help so perhaps it's a combination of several problems. I didn't get a chance to open the cap at the lights as it was idling fine anyway. I'll see how I go on the way home.