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Sticking clutch on a GPX

Discussion in 'Technical and Troubleshooting Torque' at netrider.net.au started by jd, Dec 22, 2010.

  1. Not really a problem per se, just more of a minor annoyance I have with my GPX250. When the engine is cold the clutch doesn't seem to want to fully engage. If I try shifting from neutral to 1st at idle it'll stall, though I can get around the problem simply by giving it a few revs and holding the brake to stop it from moving forward. Once into gear for the first time though everything works perfect, and I can happily shift between N and 1st without any drama, even though the engine is still cold.

    Since the bike still has less than 4,000kms on it clutch wear seems unlikely, and I would have thought any abuse of the clutch by the previous owner would if anything result in the clutch slipping rather than failing to release (but could be wrong on that). Thinking it might be down to the oil I'm using (fresh sumpful of 20W-50 Mobil motorcycle oil) since there also seems to be a slight amount of sluggishness in the gearbox when cold as well. Oh and no problem with the adjustment of the clutch cable either, that was dead on spec. when I bought it (even though I have now changed it to my preferred non-factory setting).



    Any thoughts/suggestions?
     
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  2. The 20W-50 might be part of the problem. What you describe sounds more like oil drag than the plates failing to properly separate. Try a 10W-40 or thereabouts. Even a 15W-40 or 50 might help.

    In the old days of kickstarts and separate lubrication for the clutch and primary drive, usually with heavy, sticky monogrades, the "cure" was to give it a couple of kicks with the clutch pulled before attempting a start. Dunno how you'd do it on a lecky foot only bike.

    Clutch abuse can result in the fingers of the clutch basket developing notches which impede the free movement of the plates. I've seen it a lot on well worn British clutches but it seems to have been largely eliminated by the Japanese except in extreme cases. I'd be surprised if even the most sustained abuse could destroy a modern clutch on a 250 in such a manner.
     
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  3. What is the spec'd oil for the bike. 50 seems high. Most modern bikes run 30. If 30 is spec'd I'd run 40 in Aus summer. Also, Pat is right. The lower number is more important for starting, so even a 5w would be better for summer.
     
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  4. Thanks Pat. I'm only using 20w-50 at the moment because the previous owner threw in an unopened bottle when I bought the bike and figured it'd do for the time being. It is actually at the high end of the recommended oils for the bike, so I'll give switching to a 10w-40 a shot and see how I go.

    Edit: Of course things probably aren't helped by the fact that although it's summer it's still far from warm of a morning. Was only about 5 or 6 degrees yesterday when I left for work.
     
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  5. I'll go along with the heavy base oil (20w) as being the probable cause...

    Simple trick rather than wasting it....1] let the bike warm up for a few minutes before 2] pull in the clutch 2 or 3 times before selecting 1st gear which may help the clutch plates to seperate.
     
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  6. JD, welcome to the GPX family :)

    They all do that, it's a common GPX "feature". You'll get used to starting her up with the front brake engaged.

    It's not a problem when the oil warms up a bit or after you break the "stiction" by turning over the engine while the brake is on.
     
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  7. Ah I see, must be on the same feature list as the piss-poor chrome and easy-strip body bolts that seem to be made from some sort of semi-metallic cheese.

    Knew there was a reason I liked Suzukis better. :p
     
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  8. I've had Suzuki's that you couldn't even push with the clutch in when they were cold. But as a current kwaka owner I'm allowed to agree with you.
     
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  9. Sounds familiar. Wasn't an oil-cooled GSX by any chance?
     
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  10. gsxr yes
     
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  11. It isn't just GPXers that do it. To a greater or lesser extent, all motorcycles do it. Bikes with dry clutches do it a lot less, but they jingle like a hari chrishna on speed while they idle, so....

    There are some things you can try to diminish the problem.
    (a) Start the bike then pull the clutch in, (all the way in - as far as you can) and give it a couple of sharp revs, to about half redline. Then, let the revs drop back to proper idle, hold the front brake and tap it in firmly and positively. DON'T try and ease it in, because you'll round off the teeth of the dog clutches, and you don't want to give that much money to a bike shop for no reason. You could give it to me instead.
    (b) Before starting, engage 1st gear, pull the clutch all the way in, and try to push the bike, forward and back, like you're trying to 'rock' a bogged car. Easier to do while standing beside the bike than sitting on it. At first, it won't move and you'll think the clutch is broken, but persist, and eventually it will move but with drag, and after a minute or so, only slight drag. By now your hand should be tired and your visor should be fogged up, so you'd better start the bike and go.
     
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  12. Bugger that! I just pulled the clutch in and started it with the front brake on hard. Simple.

    Oh and I like kawacheesy bikes :)
     
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  13. Thought so, my Katana does the same thing.
    Makes moving it around the shed a pain in the butt, often quite literally given it doesn't currently have a seat.

    Kneedragon, option a is what I'm already doing - and I certainly don't try and ease it into gear (it'll take my booting and like it). I'm with Rob though that option b sounds like far too much effort. I'd rather drop it off the centrestand in gear than bother with that.
     
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  14. My little Spada grabs for an instant when I hit the starter - didn't worry me at all but nice to have an explanation, thanks...
     
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