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Clutch problem GPX250r

Discussion in 'Technical and Troubleshooting Torque' at netrider.net.au started by DerekL, Apr 18, 2011.

  1. Recently brought a 2nd hand GPX250r.

    16,000km, 2006 model.

    Didn't notice any problems on the 3 hour ride home (but I was on the highway so I wasn't using the clutch/gears much). I got my friends dad to service it and today I noticed a problem.



    Symptoms:
    -Clutch doesn't go all the way in when the lever is pulled in. E.g. it will roll forwards when stopped in first (this gets worse as the engine heats up. This doesn't happen when I have just started riding the bike)
    -Gears sometimes a bit hard to change (this gets worse as the engine heats up. This doesn't happen when I have just started riding the bike)
    -After riding I can't start it in 1st gear. I have to switch to neutral and start it then change to first OR wait a bit for it to cool down
    -After a long ride (3/4+ hours) I could start it in neutral but couldn't get it into first (even if I rev'd it up high and put it in 1st), the revs would just dissapear and it would stall. I waited about 4 minutes and got it going again no problem.
    -Will jerk forward when switching from neural to first (as discussed later on in the thread is common on GPXs..)







    We've put in 20w50 fully synthetic oil (which I thought would be too thick.. Would this be the cause of it since it's using a wet clutch?).
    I personally haven't taken a look at the clutch cable yet. He took a quick look and said it looked okay (the bikes at his house still).

    Personally I think it's quite likely to be the clutch cable is stretched/whatever, but he thinks it's likely the oil. I'd just like to get a few opinions on how we should go about tackling this. Is it easier to try and fix the cable first or just go about and get all the oil out first?

    Thanks
     
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  2. Also if anyone has a link to a 2006 gpx owners manual that would be extremely helpful
     
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  3. https://netrider.net.au/forums/showthread.php?t=120914
    No real difference between the '85 and '06 model so still useful.

    As for the clutch probably just be a simply matter of adjusting the cable at the clutch and/or lever ends as described here:
    http://faq.ninja250.org/wiki/Adjusting_the_clutch_cable

    Also possible it may have reached its limits and needs replacing, in which case you'll be wanting this:
    http://faq.ninja250.org/wiki/Replacing_the_clutch_cable

    Edit: Oh and I'm running 20w-50 in my GPX at the moment (not by choice). I do get it lurching when shifting from N to 1st the very first time I try it on a cold engine, but once the "sticktion" is broken it works fine from then on. Shifting gears certainly is never a problem, and that's with an ambient temp. below 5 degrees.
     
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  4. This is common on the GPXs soon after start up. Pump the clutch lever a few times before clicking down into first and the 'jerk' becomes small. Make sure your hand is on the brake ;)

    When you're slowing (but still moving), pull the clutch lever in, can you hear the clutch scraping or are you totally free wheeling? If you can hear it scraping, try adjusting the lever. You probably have the friction point too far in (too much play).
     
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  5. Gave the clutch plates a good clean. Loads of gunk in there. Alls good now, cheers : )
     
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  6. Okay so maybe not.

    We gave it a clean and it ran quite well. However the problem has come back (but not as bad).

    Another symptom I noticed was that it pulls forwards at different rates. Sometimes it will pull harder then others.

    Also it idles around ~750rpm and pulls forward at that rpm. When I rev it it won't pull forwards anymore. Wtf?
     
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  7. Discovered a new symptom today. The problems still there.

    The clutch/gears has no problems at all when I've just started up the bike. However as I ride more and more it gets increasingly difficult to change into gears.

    Today when I started up the bike after it being off for about 2 minutes, I pulled the clutch in while it was in first and it wouldn't turn on (starter motor working). Had to put it into neutral and then into first. It took a few tries before it would turn over in neutral.

    After a long ride (3/4+ hours) I took a quick break by the side of the road. I didn't turn the bike off, just put it in neutral as I stretched etc. I got back on the bike and put it in first and it turned off. Started it in neutral and then put it back into first and it died again (revs dissapeared). Started yet again in neutral and took the revs up high-ish and droped it into first, yet again died.

    I've updated the list of symptoms at the top.
     
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  8. The clutch is scraping. But it doesn't do it when the engine is cold (or doesn't do it much/enough for me to tell)




    Here's the updated symptoms list for convenience...

    Symptoms:
    -Clutch doesn't go all the way in when the lever is pulled in. E.g. it will roll forwards when stopped in first (this gets worse as the engine heats up. This doesn't happen when I have just started riding the bike)
    -Gears sometimes a bit hard to change (this gets worse as the engine heats up. This doesn't happen when I have just started riding the bike)
    -After riding I can't start it in 1st gear. I have to switch to neutral and start it then change to first OR wait a bit for it to cool down
    -After a long ride (3/4+ hours) I could start it in neutral but couldn't get it into first (even if I rev'd it up high and put it in 1st), the revs would just dissapear and it would stall. I waited about 4 minutes and got it going again no problem.
    -Will jerk forward when switching from neural to first (as discussed later on in the thread is common on GPXs..)
     
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  9. Have you tried adjusting the free play you have in the clutch lever so it stops scraping? I think it was probably stalling when it was dying as you put it into first because the clutch lever is not fully engaging the clutch.
     
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  10. Clutch lever has been adjusted.
     
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  11. I had a lot of dramas with my 2002 zzr250 clutch and gearbox when i ran 10w40 fully synthetic oil. All was fixed when i switched back to 10w40 semi synthetic.
    My mechanic said never to put fully synthetic in the engine but i didnt listen - thought i was doing the bike a favour... should have listened. Now my scottoiler is putting the fully synthetic on the chain instead ;).
    Guess the expensive stuff was too good for my bike eh!

    Admittedly my clutch was slipping more then gripping at odd times, but there was a few quirks like you mention, extra noises etc... 20w50 might be too thick?
    Food for thought.
     
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  12. From the symptoms described your clutch is sticking. Uusally and in order of probablility these are caused by incorrect clutch cable adjustment, stretched clutch cable or stuffed clutch plates.

    Usually though the symptoms are worse when the bike is cold (oil is thickest) not the reverse as you have described.

    However a few things you have said puzzle me.
    Not sure why you would want to do this anyway. But what exactly do you mean by "can't start"? Do you mean nothing happens when you hit the starter? Could be a faulty neutral switch, a fault but totally unrelated to the other symptoms.


    Revving up while trying to select first will make it harder to select first. And when it does selct you are likely to get an almight clunk and possibly the bike will jump forward. Only try selecting first at idle revs. Try holding the clutch in for a second, and if you cannot select first easily try letting the clutch lever out a little slowly, putting it back in quickly when you do select.

    You said your lever was properly adjusted. Exactly how much slack have you got. Normal for most bikes is about 2-3 mm that is not much more than the thicknes of a match, certainly no more than the thickness of two matches. Given the symptoms you describe I would set it to the minimum.

    If your adjustment is correct why not try changing oil. Use a non synthetic of the correct weight the manafacturer recommends and see if it makes a difference. It won't cost much more than $10 to try.

    Edit: Quite a few riders have been using Delo Diesel oil and reported much improved gear changing. See the "Oil controversy Thread" in this section. I personally didn't notice any difference but others have so give it a go. It is relatively cheap.
     
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  13. Sorry - I'm new to bikes. Is it a bad idea to be trying to start it with the clutch in and in 1st gear?
    The starter runs but it won't turn over. I then switched to neutral and it took a few goes before the engine turned over.

    I could easily select first, but the revs just died and it would stall (hence why I though giving it a few revs might be worth a shot)

    Usually though once the engine is warm it's hard to change between 1st and neutral

    Going to give that a go now, thanks mate :wink:
     
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  14. It's not harmful to start a bike in first with the clutch in, just most people start in neutral. Plus some bikes have a switch which will only let you start in gear when it recognises the clutch is in. Occasionally the switch fails and the bike does recognise the clutch is in and won't start.

    By engine turned over I am assuming you mean started.

    If the revs drop off and stall when you select first, again it seems like your clutch is sticking. Which is consistent with all the symptoms you have described.

    So back to the original questions. Is your lever adjustment correct. You said it was but how much freeplay do you actually have? 2-3mm? If this is correct, tray disconnecting your clutch cable both ends, push/pull the inner cable in and out. Is it moving freely or is it binding. If the cable is OK and the adjustment is OK then unless you have a further adjustment on the clutch itself it sounds like the clutch itself is the problem.
     
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  15. easiest first.
    Clutch adjusted correctly? tick
    idle speed can also affect selecting first gear, make sure thats ok as well.
    If it wont start in first, you may be able to disable the clutch lockout switch, If thyre is a Sidestand lockout switch, check that as well. If you disable it, fix it once your certain its not the problem.
    Change the oil to the right one. You know its not the recommended oil so change it first,
    If the clutch plates where very grungy and you Havent done an oil filter, change that as well.
    Once thats done you can be fairly sure its Not the oil.
    Then either take it to someone that Knows what theyre doing, or keep going, eliminating problems as you go.
    good luck with it..
     
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  16. Oh! If you are doing the oil, see if theres an oil screen and clean that out too ;) likely need to get a new gasket for it before you do so though.
     
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  17. Idle speed on the GPX / ZZR should be ~ 1250 rpm. Less than 1000 rpm and the bike is liable to cough and splutter when you go full throttle. Above 1250 rpm and the bike will overheat too quickly in warm weather.

    Idle speed should be adjusted when the bike is fully warmed up, not when it is cold.


    When cold starting the bike, you will need to use choke to start the engine and keep it from stalling while warming up. I generally aim for a stable 2500 to 3000 rpm before I ride off about 15 seconds later. It's better to warm the bike up by riding it conservatively, rather than sitting in your driveway for several minutes, because movement forces the oil to circulate.

    Once riding, how quickly you can dial the choke back without the engine stalling at the next traffic lights / t-intersection depends on the ambient temperature. In summer it might be as little as 15 seconds, in winter it might be two to three minutes, experience will tell.
     
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  18. On that topic, once when I brought my ZZR250 to my independent mechanic for a major service, he took all the premium unleaded out of the tank and replaced it with standard unleaded.

    His explanation was two-fold (but my memory's getting a little hazy so I might not have this 100%), firstly, he said the the carbs were easier to balance on unleaded, and secondly, he said the additives that are put into Australian petrol to raise the octane level to 95/98 can build up and clog the very small parts in the carbs of a GPX/ZZR.
     
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  19. I'd be a fraction sceptical of that. I'd like to know what he used that hi-oct for as soon as you were out of sight...

    That said - I've always been taught that it's not a kindness to throw higher grade fuel at a motor than it needs. There is a potential benefit with the added level of detergents and cleaners, but just using a higher octane than necessary is a waste of money at best. If you tune the motor for that higher octane, by increasing the spark advance and (possibly) fitting a thinner head gasket or otherwise increasing the compression a little, well that's another story. But if you're going to leave the motor tuned so that it runs fine on lower grade, then run it on lower grade.

    I forget the specific technical term for it, but there's more heat in a cc of 95 than 98, and that heating capacity goes up each time you go down a grade in fuel. This is part of the reason diesels are so fuel efficient. Diesel is a much lower grade of fuel than any petrol. The limiting factor is how much compression and ignition advance you want to run.

    Back up until the 1970s, Australian builders and tuners and racers rebuilt their motors with high compression, put huge jets in their carbs, and ran pretty much everything on methanol. The fuel consumption when set up like that, was something like double what it used to be on petrol. (This in conjunction with the fact that methanol cost 4 ~ 8 times as much per gallon as petrol.) It was fairly necessary because most of the petrol available here at the time was supposed to be 88 Octane, but was usually much worse. Have you ever wondered why old cars and bikes typically have a compression ratio of 6:1 or 7:1? Crappy combustion chamber design was one reason, but the cat's p1ss sold here as fuel was the other.

    Power increase by doing this was typically about 40% ~ 55%. It's a bit hard to say exactly because must people also put big cams and big valves and different pipes and stuff on, all at the same time. Long term reliable these engines were not, but they certainly had some get up and go. You should have heard the wailing and gnashing of teeth when methanol was broadly banned across all classes in the '70s.
     
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  20. Cheers kneedragon, some interesting history there. :)

    I'd thought of the detergeants / cleanliness advantage of "Premium" fuel, but I don't think it's cost effective to keep a GPX / ZZR running long enough for that to become an issue, hell the bike doesn't even come stock with a fuel filter!

    The carburetion on the ZZR is a biatch at the best of times, so I'm inclined to believe him on point (1), having said that I was a bit sceptical about point (2), perhaps he's biased by Australia's history of poor quality fuel.
     
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