A question about a Nobel

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Hello, how do I separate the Nobel 200 chain case from a Sachs 175 engine? Is there anyway to lock the gearing on the engine? The sprocket spins in either direction and I

[Jean]

I suggest you get on to Mike Ayriss who runs the Nobel section of Register and has a lot of experience with them .  His email address is michael.ayriss@virgin.net.  Good luck!

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Thanks Jean, I

[Bob Purton]

I dont know how far you are stripping the motor down but if you are taking the barrel off you can take the gudgeon pin out of the piston and put a metal rod through the small end then put a couple of wood blocks between the end of the rods and the where the barrel seats, put the engine in gear and then undo the nut. Its often worked for me. Alternativly make up a tool to hold the flywheel from rotating, a long flat bar with a couple of pins through it to engage into the openings of the flywheel, again you have to put the engine in gear.Some sprockets themselves have two holes in them and these are for use with a simiular tool, a flat bar with two pins through it and a cutaway to go around the nut that you are trying to undo.This last method is proberbly no good to you because the chain case will be in the way. Hope this helps, Bob P

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Thanks Bob, this is excellent. I haven

[Bob Purton]

Well Mike, It will either undo the nut or unsieze the piston! Either one would be usefull!

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As were on the subject of seized engines, what is the usual procedure to free the piston?

[robbie2flippers]

 Hi, This is how I go about it and have been lucky so far. I freed my Peel P50 in 1975, a Villiers 8E on Jean's Gordon and last month a 1949 BSA Bantam engine. One thing is TAKE TIME, you don't want to break the piston. After cleaning the outside of the engine, I take off the cylinder head and spray WD40 etc. onto the piston head. When it disappears down to the siezed rings spray in more. It could take 2 or 3 days. I then LIGHTLY tap the piston with a short length of wood. NO HAMMERS. If it moves slightly I put more de-ruster in. I have a go moving the flywheel, more oil. With the Bantam engine I was a bit more drastic. I freed of the cylinder and turned the flywheel so as it rose with the siezed piston. Pieces of hardwood were placed between the cylinder and cranckcase, turning the flywheel to bring the piston/cylinder down hard on the wood, hopefully to free the rusty rings. Luckily it freed the Bantam but the rings are stuck in the piston. If this fails, try the heat method. Be carefull as there is all that flammable oil about. A blow lamp slowly heating up the cylinder fins around the rings area. Let it cool and put more WD40 down the cylinder. It will release, it just takes time. I also did this trick with the Peel, Fitted new rings  and I enjoyed running MHX 90 C for about a year. Hope this helps. Good Luck. Bob D.

[Trident]

To free seized piston try:
Oil arround the sides of the piston and allow to soak in.
Apply heat if possible with a blowlamp on the barrel.
Allow to cool.
Reheat the barrel and hit the piston crown with a piece of wood + mallet.
If this does not work, try a bigger hammer.

[robbie2flippers]

Hammers only if you are reboring and fitting oversize pistons.

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Cheers guys!! Looks like I

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I have to hand it to Bob D, the two pieces of wood between the cylinder and crank case really worked a treat. Mike