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Thread: 50cc 2 stroke clutch problem

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    Default 50cc 2 stroke clutch problem


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    Morning all! Some of you may remember that my son managed to kill his 50cc 2-Stroke Chinese piece of rubbish, but he has spent the last couple of weeks replacing the piston and cylinder, and joy of joys it started up last night. However, whilst ordering the spare parts he also ordered a new clutch lever (as his had bent when it fell) so he simply unhooked the existing clutch cable from the old lever, replaced the lever / handle and re-attached the cable. Now the clutch doesn't disengage (bike is stuck in gear even when clutch lever is pulled) so we have tried adjusting it at the handle end but no joy. It's impossible to adjust the screws at the clutch end as one of them won't budge (hubby thinks it's fixed - I think it's seized). Masai clutch screw.jpg
    Whilst the casing was off we could see the clutch pack moving but some of the plates were stuck together - they came apart easily enough when manually separated but stuck back together again when clutch lever was pulled. Since we haven't touched the clutch at all (other than the lever) do you think it's still just an adjustment issue or do the sticky plates indicate something else. It's been a few weeks since the bike was drained so I thought the clutch plates might be stuck together because of that and that it might resolve itself once it was up and running again and the oil had warmed up. Thanks in advance.

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    Should Get Out More ink ink's Avatar
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    Default Re: 50cc 2 stroke clutch problem

    Are you using the right grade of oil?

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    Default Re: 50cc 2 stroke clutch problem

    Does the lever have any free play? There should usually be about 5-10mm of free play measured at the ball end of the lever. If it has none, the clutch cable needs adjusting. The nut you've circled needs loosening off then the other nut tightened to hold everything in place.

    The cable.looks to be pulled about as tight as it will go so I would not be surprised if it's that.

    If it's the adjustment, then that nut has to move one way or another, even if it means a new cable.

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    Default Re: 50cc 2 stroke clutch problem

    Ah, just read post again. If pulling the lever back to the bar still doesn't release the clutch, it's not likely to be cable adjustment. There will be some ratchet or can mechanism inside the clutch casing where the cable attaches, and it will have been assembled incorrectly or a small part fallen on the floor.

    How does the lever feel? Any resistance? Does it move at all?

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    Should Get Out More Julian_Boolean's Avatar
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    Default Re: 50cc 2 stroke clutch problem

    Sounds like sticky clutch plates., try taking the clutch apart and cleaning the clutch plates in clean oil.

    Sent from my SM-T560 using Tapatalk

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    Default Re: 50cc 2 stroke clutch problem

    Quote Originally Posted by ink ink View Post
    Are you using the right grade of oil?
    As far as I know...https://www.ipone.com/wp-content/upl...nance-Box2.pdf

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    Default Re: 50cc 2 stroke clutch problem

    Quote Originally Posted by a_morti View Post
    Ah, just read post again. If pulling the lever back to the bar still doesn't release the clutch, it's not likely to be cable adjustment. There will be some ratchet or can mechanism inside the clutch casing where the cable attaches, and it will have been assembled incorrectly or a small part fallen on the floor.

    How does the lever feel? Any resistance? Does it move at all?
    Thanks for the reply. Lever seems to have good resistance and the clutch pack does move when it's pulled, but some of the plates stick together. We haven't touched anything within the clutch casing so no fallen parts or incorrect assembly. I guess we're gonna have to try cleaning the plates and somehow get that adjustment nut freed up.

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    Default Re: 50cc 2 stroke clutch problem

    Quote Originally Posted by Julian_Boolean View Post
    Sounds like sticky clutch plates., try taking the clutch apart and cleaning the clutch plates in clean oil.

    Sent from my SM-T560 using Tapatalk
    Thanks for the reply. I guess we'll have to try that but just didn't want to have to drain it again since we only filled it up yesterday

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    Default Re: 50cc 2 stroke clutch problem

    Could any fragment of the old piston have got in the clutch and blocked it? Try pulling clutch apart, clean and oil the plates.

    When putting clutch back together, it's essential to tighten the bolts over the springs sequentially, or you'll break the basket.

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    Default Re: 50cc 2 stroke clutch problem

    Clarify this for me please. Bike stalls when you put it into gear or no drive.
    Re fit the original lever, see if the problem goes away! May have an incompatible lever.

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    Default Re: 50cc 2 stroke clutch problem

    Quote Originally Posted by sadlonelygit View Post
    Clarify this for me please. Bike stalls when you put it into gear or no drive.
    Re fit the original lever, see if the problem goes away! May have an incompatible lever.
    Thanks for your reply. The bike lurches forward and stalls when you put it into gear. I'm pretty sure it's not t he lever as the new one was an exact replacement for the old one.

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    Default Re: 50cc 2 stroke clutch problem

    So, I came across a really useful video on YouTube which explains to a numpty like me how the clutch mechanism on a bike works....https://www.youtube.com/watch?time_c...&v=agLa0A8GAfc

    I mistakenly thought that the clutch plates should move forward with the pressure plate when the lever is pulled but it seems that pulling the lever pushes just the pressure plate forward thereby allowing the plates to separate and stop transmission to the gearbox. (Hope that's right anyway!!)

    As you can see from my video clip, the pressure plate on this bike doesn't push forward evenly - it seems to be sticking on one side and to the friction disc underneath. It could be uneven tightening of the bolts (not done by us I stress but perhaps by the repair shop before we picked it up??) or just really a sticky plate underneath. The plan is to take the all the plates out, clean them up, soak them in clean oil and re-install - taking care to tighten the bolts evenly and in a criss-cross pattern. I really hope that works! https://photos.app.goo.gl/VLzyacHJHwUArxxUA
    Last edited by Acorn; 18-09-19 at 08:38.

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    Default Re: 50cc 2 stroke clutch problem

    Be warned the bolts can break off the threaded section very easily so do not over tighten. Tight is tight too tight is broke

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    Default Re: 50cc 2 stroke clutch problem

    I suspect it'll be obvious once you open it up. Some piece of grit or debris will be in there. If you're less lucky something may have been bent.

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    Default Re: 50cc 2 stroke clutch problem

    Quote Originally Posted by Acorn View Post
    Thanks for your reply. The bike lurches forward and stalls when you put it into gear. I'm pretty sure it's not t he lever as the new one was an exact replacement for the old one.
    Ok, the clutch is not disengaging enough/at all.
    Personally I'd whip out the plates and very carefully rebuild it. Dont put the cover back on, pop the bike into gear and see if you can push the bike with the clutch pulled in. Bike hopefully should roll if you've done it right! As has been said,the clutch fingers and their threads are delicate, so no gorilla tightening!
    Just seen the video.the outer basket only fits on properly 1 (or 2) ways. Often there are arrows that should line up. Check also that all the plates are the same, some clutches have different sized plates that need assembling in a specific order.

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