BSA 120cc Flywheel removal.

[sidevalve44]

I am stripping a BSA 120cc that I have removed from an old Howard 200.

I need to remove the flywheel to access the ignition and to remove the crank assembly etc.,

So, any advice on how to do this would be appreciated.

1) How do you hold the flywheel to stop it turning as there are no convenient flats to wedge a bit of wood under or holes to stick rods into ?
2) What kind of flywheel puller is needed to actually remove it from the crank ?

Many thanks

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1. 

[charlie]

Can you hold the crank using the drive pulley on the other end? Once you have removed starter pulley and engine cowl you should be able to see if the flywheel has any tapped holes for a puller. Photo would help.

[vhgmcbuddy]

To lock the engine I find some starter cord down the plug hole is very effective, being nylon it won’t do any harm to the internals.from memory there is some holes threaded in the flywheel under the plate under the starter pulley to make up a puller, however last time after undoing the pulley I levered the flywheel with a pinch bar in line with the key way, placed a block of wood on the end of the crank and gave it an almighty clonck a couple of times. The shock should be enough to bounce the flywheel off.

[sidevalve44]

I’ve removed the cowling and there are no tapped holes visible. However, The starter pulley is threaded onto the crank and that needs to be removed before I do anything. I believe, as s1g has said, that there are some holes behind the metal plate that is immediately behind the starter pulley but, I need to remove that first !
Holding it from the other end would surely risk damaging the crank by putting torsional stresses on it that it’s not designed for. Also, levering it off is a no go as there is a thin ally plate between the flywheel and the engine case that would not take the pressure.

However, I have a cunning plan and will update you when I’ve put it into operation !

[vhgmcbuddy]

You don’t need much pressure at all when levering, that’s how I’ve done a few anyway, otherwise, make up a plate with 3 holes, weld a nut into the centre one, and thread some bolts into the holes in the flywheel, then you’ve got a crude puller.
The starter pulley should just unthread, I find the nylon cord down the plug hole the safest way to lock the engine. When I’ve had really tight ones in the past I’ve had to resort to removing the head and placing a block of wood on the top of the piston, then temporally refit the head.
I’ve had a couple of the coils fail on me on this engine, and a couple of dicky carbs,but apart from that they are almost bomb proof. I can’t believe how thick the castings on the crankcase are, you certainly wouldn’t see engines like this nowadays.

[sidevalve44]

I may well try the bit of wood technique. The head is off at present but won’t take a few moments to put back on (that’s why I love side-valves!) Yes, you are correct the starter pulley should unscrew, it’s partially unscrewed at the moment but is a bit rusted up. The engine has had a hard life, it’s on +.040″ on the piston so, no more rebores possible ! Might just have to make do with a new set of rings (if available). The are very, very sturdy though as you say, very similar to the Kohler 4hp on my other Howard.

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