Back wheel won't turn

Discussion in '2-Stroke Engines' started by bilboby, Jul 6, 2010.

  1. bilboby

    bilboby Member

    Hello & apologies if this subject has been mentioned before,

    Having managed to wreck my first chinese made rear drive friction engine and toddled with the idea of replacing with a Loncin 48cc mini chopper type i've now reverted back to the first MB project which got me into MB'ing.

    I've taken off the rear friction engine and replaced with yet another chinese type 80cc which i had spare and fit's in between the V-frame. However although i had no problems before when using this setup i've now got the problem of 'the back wheel' not turning thus it's locked. The chain slack is about 3/4 and passes via it's idler however the wheel only turns when taking off the MB's chain. On checking the build i believe everything to be as it should thus i'm at a loss to the problem, i should also mention that the accelerator/clutch cable felt quite tight so i gave it slack but still with the wheel problem.

    Any help on the cause of the wheel lock will be much appreciated and i again apologise if this topic has been mentioned elsewhere.

    If i'm being honest i should point out that the V-frame type setup with a long chrome muffler and black painted alu gas tank look's far more attractive than the rear friction drive setup but that's only my opinion.


    NB: No doubt other's have pointed out before but if the like's of myself buy cheap chinese made engine kit's in the hope of saving big bucks then i suppose we warrant what we deserve. Unfortunately US made kit's and the vendors rarely (if at all) ship over to W Europe.
    Last edited: Jul 6, 2010

  2. Porkchop

    Porkchop Member

    What name brand friction drive and engine have you been using ? Can you post photos ?
  3. Al.Fisherman

    Al.Fisherman Active Member

    Lets find out the cause first...Remove the chain and see if the rear tire will rotate. Knowing this will give us a good place to start. May I assume since the engine is mounted in the "V" it is in fact a China HT chain drive that the problem refers to?
  4. bilboby

    bilboby Member

    Unfortunately i have no reference on type/model of chinese friction engine in use as BGF didn't give any details nor am i sure if the below photo's will be of much use in identifying the friction drive model?


    Attached Files:

  5. AussieSteve

    AussieSteve Active Member

    Ron, he said the wheel turns when the chain is off, but this is getting confusing.
    Is it about a Chinese HT chain-drive setup or a friction drive as in the pics?

    bilboby, let's keep it on-topic to avoid the confusion.

    Is the rear wheel not turning due to poor clutch adjustment? (You are pulling it in, I assume.)

    If it's adjusted OK, it could just be that the clutch plates are sticking due to sitting around for a while. Try pulling the clutch lever in and giving the bike a few good stiff rolls forward and backward a few inches with some weight on it to loosen things up.
    Last edited: Jul 6, 2010
  6. srdavo

    srdavo Active Member

  7. AussieSteve

    AussieSteve Active Member

    Good thinking again, Dave.
    Just thinking, though. Bilboby says the wheel turns OK with the chain off, implying he's pulled the chain off to check. He should have noticed if the chain was bunched.
  8. bilboby

    bilboby Member

    It's about the Chinese ht chain drive set up which having refitted onto the bike the rear wheel won't turn. Steve, i've taken onboard what you've suggested by pulling the clutch lever in and giving the bike a few stiff roll's forward etc but alas the back wheel still refuses to budge however as you've quite rightly pointed out from my original post, the wheel run free'ly with the main HT chain off. I'll post a pick of the setup later on today.

    NB: Sorry chap's for any confusion
  9. AussieSteve

    AussieSteve Active Member

    Double-check that the chain isn't bunching under the countershaft cover.
    Next, pull the plug out and see if the engine turns when you roll the bike forward, (with the clutch lever out, (engaged), to check that nothing is seized in the engine).
    If the engine turns over OK, you'll probably need to pull the clutch top plate off, at least, before the clutch will free up.
    A pic might[/i\] help.
  10. bilboby

    bilboby Member

    Will confirm that the chain was not bunched

    I should now mention that having read the thread (cheers srdavo) 4788 i tried the exercise of HT chain fitted with spark plug off and indeed found the back wheel does turn. However refit the plug and i'm back to square one.

    Although so far the problem hasn't been resolved, cheers anyway everyone for your time and help.
  11. AussieSteve

    AussieSteve Active Member

    You've isolated the problem very nicely.
    The clutch is sticking.
    Remove the RHS side-cover, then the lock-screw and clover nut. (Count the number of turns on the clover nut to aid re-assembly.)
    Next, take off the clutch top plate with spring and try rocking the bike back and forth again. Also, a bit of jiggling of the clutch driven gear will help. Let us know if it frees up.

    Sorry, that wasn't quite right - the clutch is jammed OR the engine is seized.
    Remove the countershaft cover, fit a socket to the countershaft nut and see if the engine turns over at all. (With the clutch lever out, (engaged).)
    Last edited: Jul 6, 2010
  12. bilboby

    bilboby Member

    Cheers for that one as although too late now (off to work) i'll give your suggestion a good look into tomorrow. I've now completely taken off the HT chain engine so as to hopefully ease working on it better.

    I'll let you know how i get on but in the mean time i've posted some photo's of the various engines i have at my disposal inclus the current problematic engine. Bear in mind i've taken out the clutch pin & ball bearing.

    Steve & everyone else cheers for this afternoon's help

    NB: One of the photo's is of a chopper bike which a guy was throwing out so i unfortunately give it a home but a restoration job is needed. to all & cheers Steve.

    Attached Files:

  13. AussieSteve

    AussieSteve Active Member

    No worries - afternoon to you, very early morning to me, (2:21am). I'm off to bed. (I'll check out the pics in the morning.)
  14. Luka

    Luka Member

    If the engine was seized, the wheel wouldn't turn even with the spark plug removed.
  15. Luka

    Luka Member

    Very early morning for you, late morning for me, afternoon for bilboby...

    Small world.

  16. Al.Fisherman

    Al.Fisherman Active Member

    If the rear wheel WILL rotate with the plug OUT (chain on and rotating the engine) but won't with the plug IN then the piston is hitting the plug...

    I see it is a pull start..remove plug pull on rope, if engine rotates without plug, but won't with plug, pull plug, and make sure you have correct plug. If it is the correct plug check gap. If it's ok pull the head as I'd bet there is something between the piston and head.
    Last edited: Jul 6, 2010
  17. AussieSteve

    AussieSteve Active Member

    Of course you're right. I was pretty tired.
    It's the clutch.
  18. Al.Fisherman

    Al.Fisherman Active Member

    Steve, how can it be the clutch when the only variable on the rear wheel turning is weather the plug is installed or not installed. Has nothing to do with the clutch at this moment.
  19. AussieSteve

    AussieSteve Active Member

    The wheel won't turn with the clutch pulled in.
    (So I assumed that Bilboby meant that the wheel would not turn freely due to compression w/ a stuck clutch.)

    Just been re-reading the thread - something's not right here.
    Bilboby, when you say the wheel won't turn, do you mean that it won't turn due to compression, or is it locked solid? With the clutch out, won't the engine turn if you turn the wheel forwards with some pressure?

    Ron, I wonder if maybe we're both right?
    Last edited: Jul 6, 2010
  20. Al.Fisherman

    Al.Fisherman Active Member

    Whatever the reason, what needs to be done is to isolate the problem (at least partially) is to remove the chain and use the pull rope to turn over the engine, as in trying to start it, with and without the plug...that's for starters. This will at least eliminate the engine revolution issue. These engines run on such low compression, my son at times starts his by spinning the rear wheel by hand. If it isn't a pull rope start rotate the crankshaft nut (holding the magnet on) clockwise with a ratchet and socket or BOX wrench. No chance of breaking the nut loose.
    Last edited: Jul 7, 2010