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2002 Suzuki GSX-R 600 - suddenly running rough???

Discussion in 'Technical and Troubleshooting Torque' started by Weasel, May 14, 2010.

  1. Hi folks,

    I would greatly appreciate any suggestions and/or advice in regard to the following:

    I recently started my 2002 Suzuki GSXR-600 last night after a period of several weeks. Despite letting it warm up appropriately etc, it sounded lumpy and was misfiring as I rode it gently down to the servo to put some air in the tyres and fill it with fresh fuel (BP Ultimate Premium Unleaded).

    On the way home it still ran roughly for part of the way, then suddenly seemed to kick into life and was the same old bike that I've known and loved etc.

    This morning on the 40km commute to work it ran just fine.

    However, when I went to leave work this afternoon it was slightly difficult to start, and all the way home and since it is running rough again.

    It cut out on me at the lights twice and basically sounds and feels a lot like my old Kawasaki ZZR 250 - down on power, sounds lumpy/tinny and as though it's not running on all 4 cylinders.

    Does anyone have any idea what the problem may be?

    Could it be a bad batch of fuel? Fouled plugs? Clogged filters? In dire need of a service and tune???

    I'm planning to book it in to my usual mechanic soon, but in the meantime the suspense is killing me!!!


    "I feel the need.... the need for speed!"

  2. Could be a whole bunch of things - but to start with, is the bike EFI?

    Now, some possible causes - vacuum leaks are a common cause of rough idles, a quick check over of the bikes vacuum tubes will reveal if they are at fault. If the tubes are fine it could still be a vacuum problem, but the fault being elsewhere (typically tight valve clearances). Vacuum/clearance issues will also cause poor performance, but it is likely to be constant.

    If you think not all cylinders are firing there is an easy way to test - warm the bike up a little and squirt a little water on the headers. The water should instantly turn to steam (note - don't touch the headers to see if they are warm!). Not a conclusive test, but it is quick and easy.

    If you suspect plugs or filters, pull them out and inspect. But again, I would expect that if these were the cause the problem would be more constant.

    Be sure to check your idle settings and choke (if you have one) - if either are not working correctly it can do fun things to your bike. Also take a sniff of your exhaust to see if it smells like petrol (well, more so then normal), that could be a sign you are running rich (again, possibly because of idle/choke). Taking a look at your plugs will also give you an idea on if you are too lean/too rich.

    Finally, it could be that the bike is just cold and is not happy about it. A general tune and service could do wonders to improve its mood ;)
  3. Thanks for this Godspetmonkey - you've given me some good starting points!

    Yep, the bike is EFI - could it be clogged injectors?


    "I feel the need....the need for speed!"
  4. Normally a bike won't cut out altogether if one cylinder stops working, but if two cylinders stop working then the bike will most certainly cut out, and be very difficult to start...
    First move, you need to identify which cylinder/s are not working, squirting water as above is a good idea. Once identified, check the plug for that cylinder. If it is two cylinders running cold, then ignition coil may need replacing. If it is the coil, then either 1 & 4 or 2 & 3 will be affected...
    If it turns out to be none of the above, then you will probably need professional help with injectors perhaps.. Check that vacuum hoses not kinked also ...
  5. It could be - injectors will naturally clog over time, but it is so gradual you probably wont notice. I wouldn't expect some clogging to cause a problem to suddenly appear, then go away, and then return again in short order (unless you have a habit of putting very bad fuel in your bike). Injectors are fancy elertronic items though - it could be that one of them is on the fritz.

    I would start with the easy stuff however - pulling apart your fueling system is not going to be a quick and easy job. Also check to see if you ECU is giving you any error codes (consult your manual on how to do that). The self diagnostics can be handy.

    From your symptoms I think you are on the right path - the air fuel mix is probably off. The hard to start + rough running, combined with the cooling weather makes me think you should take a look at what ever choke replacement your bike has (EFI bikes use a variety of methods, especially the earlier ones). And inspect the spark plugs (or even just one), they are a window into the running condition of your engine. In particular, look to see if the spark plugs are telling you that the bike is running too rich or too lean.
  6. Hi Folks,

    Thanks to all who provided their advice and wisdom - it's much appreciated!

    It turns out that it was indeed a clogged injector, and that the bike needed a major service and tune.

    It's now running sweet again, and I can't wipe the grin off my face!


    "I feel the need.... the need for speed!"