247 cylinder removal

[Glen]

Hi all,

just recently got a 247 21M and wanted to remove the cylinder so I can start the rebuild process, how do to I remove it?

I read somewhere to put it in a furnace and it will pull away from the engine cases.

Are there any other ways? 

Also does anyone know the paint code for the tank?

thanks

[keychange]

A rubber mallet or block of wood

[section swept]

There’s a technique to taking an engine apart and I suspect that a furnace isn’t a part of it! Where ever you read that nugget of information I’d revisit and check before going any further. It is all too common for components to grow together over time, gaskets set like stone to both surfaces and can cause some grief when you want to take something apart. 

To remove the barrel from the crankcase you will need to be careful and use gentle persuasion otherwise damage will occur. If you are trying to remove the cylinder liner from the barrel then certainly heat may be needed. May I suggest that you research some of the very good videos available on the internet and get a workshop manual of some kind, it doesn’t have to be for you bike but similar is good to give you an idea of how to go about engine dismantling. 

To help you further, if you have already removed the cylinder head ( there’s a technique to this to help prevent distortion) then make sure there’s nothing else holding the barrel ( cylinder barrel) in place. Take a sharp knife blade and ease it around the gasket gently cutting into the gasket be careful not to cut the aluminium case in this area. Apply penetrating fluid to soak into the gasket and where the barrel is thick enough apply careful leverage prising the barrel up and away from the crankcases. Once you get the barrel moving try to keep the barrel even and use leverage with care some thin aluminium sheet placed between the tip of the lever and the crankcase will help. As I have suggested before you might be better off getting hold of an old moped engine or similar and practice on this before working on your Montesa engine. Try to remember that old components can get fragile with age and a little heat from a hot air gun can help with separating components, but stay away from the furnace idea??

[Glen]

2 hours ago, section swept said:

There’s a technique to taking an engine apart and I suspect that a furnace isn’t a part of it! Where ever you read that nugget of information I’d revisit and check before going any further. It is all too common for components to grow together over time, gaskets set like stone to both surfaces and can cause some grief when you want to take something apart. 

To remove the barrel from the crankcase you will need to be careful and use gentle persuasion otherwise damage will occur. If you are trying to remove the cylinder liner from the barrel then certainly heat may be needed. May I suggest that you research some of the very good videos available on the internet and get a workshop manual of some kind, it doesn’t have to be for you bike but similar is good to give you an idea of how to go about engine dismantling. 

To help you further, if you have already removed the cylinder head ( there’s a technique to this to help prevent distortion) then make sure there’s nothing else holding the barrel ( cylinder barrel) in place. Take a sharp knife blade and ease it around the gasket gently cutting into the gasket be careful not to cut the aluminium case in this area. Apply penetrating fluid to soak into the gasket and where the barrel is thick enough apply careful leverage prising the barrel up and away from the crankcases. Once you get the barrel moving try to keep the barrel even and use leverage with care some thin aluminium sheet placed between the tip of the lever and the crankcase will help. As I have suggested before you might be better off getting hold of an old moped engine or similar and practice on this before working on your Montesa engine. Try to remember that old components can get fragile with age and a little heat from a hot air gun can help with separating components, but stay away from the furnace idea??

Thanks, I’ll give it a go.

[lorenzo]

Removing the cylinder base sleeve nuts can often prove a task in itself if a p.o. has used an ill-fitting key and rounded-off the internal hexagons - you have

removed all the nuts, haven't you ? (Maybe, not obvious to someone unfamiliar with working on these engines......)

Jarring the barrel with a hammer and piece of wood to the exhaust port, or similar usually then does the trick.

Do not lever on the cooling fins or any joint face !

[feetupfun]

The nuts are not obvious and are 7mm internal hex drive