Back wheel won't turn

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).)
 
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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).)

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.
 

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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).)

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

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

Small world.

:D
 

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.

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.
 
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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?
 
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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?

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.
 
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