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Ossa 250 Mick Andrews engine removal


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My son has inherited an Ossa 250 Mick Andrews (lucky boy!) but it has no compression (got stuck on full revs, so re-bore is likely). Steve Sell is going to sort it for me but I need to get the engine out to take to him. As a newbie to bikes, any advice, things to watch out for, or sources of info would be much appreciated. Are any special tools required? Risk of damage (eg exhaust removal?). I've found the parts diagrams and manual online, but it doesn't cover engine removal. Many thanks.

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I have a 250 MAR, but have never removed the engine ( yet )

From looking at it, I would say no special tools required, just metric socket set, metric spanners , screwdrivers , pliers and of course a hammer.

Disconnect - clutch & throttle cables, ignition wiring, remove - carb & exhaust, bash plate under engine, chain.

to remove things like exhaust , you may find that - tank,seat, side panels etc. need to be removed , but these are simple and will make access to engine better anyway.

( take some photos is a good idea if the engine ends up being out for a while and you forget how things went)

I seem to remember seeing it mentioned somewhere that one of the Ossa models needs the cylinder head removed , to allow engine removal ? ( I may have got that completely wrong, but again the cyl. head is easy enough to remove if needed)

It should all be logical & simple, leave the engine mount bolts till last, and if you are clumsy then wear some steel toe cap boots to save injury when you drop the engine.

Good luck, and just ask more questions if you get stuck, someone will answer I am sure

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It’s a long time since I last did mine, but from memory removed everything you can - tank, seat, exhaust, side panels, put the bike on it’s side and lift out. If you’re going to paint the frame whilst it’s apart put lots of protection on it before refitting the engine…

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The easiest way to get the engine out of the frame is to first remove the cylinder and head with engine in the bike, then remove the engine. It is possible to remove the engine with cylinder and head fitted but it can be a real struggle, much easier without - same when refitting. Also easier with the ignition and clutch side casings removed.

To remove the cylinder and head you'll need to remove the middle silencer as the head will catch the front of it. For the engine, remove the two rear and one of the front engine mount bolts, hold the engine by the cylinder studs and then remove the last front bolt, the engine will drop forwards and out or lift out

For engine removal the only proper tool you need is a C spanner that correctly fits the threaded ring that holds the exhaust in the cylinder. If you try and undo this using a hammer and drift to unscrew it you risk damaging the threads which are fine - also be careful when refitting as it's easy to croass thread it when it first goes in, it should be easy to make the first few turns by hand, if not, it's probably crossed. To remover the rear engine bolt a knuckle joint on a socket extension is useful as it's awkward to get at.  The only other tool needed is if you are stripping the engine and that's to remove the rapered sleeve for the clutch cush drive and a puller for the ignition flywheel but if Steve is doing the engine you won't need to bother with that

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