Villiers Mk20 4 Stroke, how do I get the pull start pulley and rotor off ?

Hi,
Fairly new to this engine rebuilding game . I've got myself a little Villiers MK20 4 stroke, I know, not very exciting or rare but you have to start somewhere, anyway .. I've removed the cowling and the head and the carb (the exhaust studs will not move, hacksaw job I think), I've removed the fan ring ? (the cast ring with the air vanes on it) from the rotor (I call the brass bit over the coil, the bit with the pull start pulley on it the rotor) and now I want to remove the rotor / start pulley assembly. There is a fairly large nut on the end of the crank, first question is which way does it undo ? Anti clock I assume, I've got an impact wrench and was thinking of using that but thought I'd ask first. Is there an easy way to lock the piston (stop the crank from turning) I was thinking of pulling the cylinder barrel and putting some wood across the crankcase under the piston maybe ? Is the rotor on a taper or has it got a woodruff key ? Also I think the cylinder head is Mullered or rather the threads holding the spark plug in are Mullered - Heli coil ? Anyone got one with good threads for sale ?
Thanks

The nut undoes anti-clockwise as you thought but it SHOULD be very tight so get a good fitting socket/spanner and belt it hard!  The nut should loosen for a turn or two and then go tight again, hit the spanner again and the nut will go lose and also draw the flywheel assembly off of the crankshaft.  There is no key, the flywheel can fit anywhere but still needs timing on reassembly, we can help you with that when you get to that stage!   You can put a strap around the flywheel to stop it turning, or some rope etc, I dont advise jamming anything under the piston but you could remove the sump and wedge some wood between the crankshaft and crankcase.

Pete.

pete
spot on mate
worst case ive used stillsons on the other end of crankshaft , but a rag on to of a wooden block with the flywheel sat onto rag ,then give socket or spanner a few good clowts with a hammer and 95% time off the come,
the other 5% ive used stillsons on the other end of crankshaft
kev

Foden wrote:The nut undoes anti-clockwise as you thought but it SHOULD be very tight so get a good fitting socket/spanner and belt it hard!  The nut should loosen for a turn or two and then go tight again, hit the spanner again and the nut will go lose and also draw the flywheel assembly off of the crankshaft.  There is no key, the flywheel can fit anywhere but still needs timing on reassembly, we can help you with that when you get to that stage!   You can put a strap around the flywheel to stop it turning, or some rope etc, I dont advise jamming anything under the piston but you could remove the sump and wedge some wood between the crankshaft and crankcase.

Pete.

Thanks for the information and taking time to reply. It worked a treat just as you said, I locked the flywheel by hooking a drive belt over it (with the engine on the edge of the bench) and then standing in the hanging loop or at least applying pressure with my foot, this served to lock the flywheel. I then used an impact wrench with a 1/2" whit socket and off she popped ! Brilliant ! Just need to drain the oil now and pull the cylinder barrel off and then the sump etc.

slim
just watch the valve push rods when lifting the barrel off as there are small caps with shims inside them ,sotimes stay on push rods and other times follow the barrel and fall into sump or floor ect and dont make a noise as they hide them selves away
kev

kevjhnsn wrote:slim
just watch the valve push rods when lifting the barrel off as there are small caps with shims inside them ,sotimes stay on push rods and other times follow the barrel and fall into sump or floor ect and dont make a noise as they hide them selves away
kev

Thanks for the tip - will watch out for those.
Dale

just helping you to miss the mistakes i made on my first villiers mk25 dismantling and reasembling
if your not sure ,just ask and we/i will be back within hours to you
better safe than costly
any parts needed i usualy have or know weres cheapest to get them from
ive pm you a link for a faster response from me mate
kev

I have acquired a Lightburn concrete mixer that I want to use with a "Villiers mk 25'', it fired once, now no spark, how do you get the fly wheel off, the nut/bolt just spins freely in ether direction, any other advice would be appreciated.