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Author: Subject: OT- Small scooter engine head gasket help
AdrianH

posted on 3/4/14 at 08:26 PM Reply With Quote
OT- Small scooter engine head gasket help

Picked up a small scooter the other week, a for parts unit, but not written off, so now have the V5 in my name. The engine had seized.

I freed the engine off and last weekend took the head and cylinder off to find bits of the piston welded to the bore.

Replacement piston and rings I have, the bore looks OK but at present I am soaking the bore with a caustic soda solution in hope to dissolve the aluminium left in there.

The head gasket was steel.

My question is would it have been stuck with any compound or sealant. It does not seem to be squish-able. not like a replacement gasket I got that will not fit!

There were two type of engine and it looks as tough this is the uncommon one.

The scooter is a 125 cc Sym Megalo and my other option is to try and obtain a cheep but good engine.

Adrian

[Edited on 3-4-14 by AdrianH]





Why do I have to make the tools to finish the job? More time then money.
Build diary at http://www.tamarisktechnicals.com/pages/roadster.html

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19sac65

posted on 4/4/14 at 05:36 AM Reply With Quote
I would have had it bored and an oversized piston kit to be safe
Try running a honing tool down the bores,that will take any glaze away and hopefully the deposits
I wouldnt build it back up until its 100% though
As for the gasket - is it 2 or 4 stroke
I seem to remember 2 stroke gaskets not being very robust
I seem to remember my moped being some sort of paper

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AdrianH

posted on 4/4/14 at 06:28 AM Reply With Quote
Sorry I should have said it is a 4 stroke.

I have been looking around for an oversize piston but not seen any. It will be honed before I fit the new piston.

It just looks as though getting a new gasket could be an issue.

I guess some 800 grit paper on glass for both the cylinder and head before reusing the old gasket may be in order.

If it does not work then only minimal loses with this engine.

Adrian





Why do I have to make the tools to finish the job? More time then money.
Build diary at http://www.tamarisktechnicals.com/pages/roadster.html

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MikeRJ

posted on 4/4/14 at 09:14 AM Reply With Quote
The steel gaskets have grooves pressed into them around the cylinder that get crushed when the gasket is used, which is why there's now no obvious compliance in the gasket.

Is it an air cooled or water cooled engine? The Megalo was also badged as 'Duke' (and I think the Euro MX uses the same engine), so if it's the air cooled engine you could have had a new barrel, piston, rings and gasket for Cylinder Bore Set for Sym Duke 125/125cc.

[Edited on 4/4/14 by MikeRJ]

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whitestu

posted on 4/4/14 at 09:27 AM Reply With Quote
If it is air cooled the gaskets aren't anything like as important - I think my old Citroen GSA didn't have any gaskets on the heads!

I think the one on my Suzuki 50 when I was a lad was copper and didn't need any gasket sealant.

Stu

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Peteff

posted on 4/4/14 at 11:29 AM Reply With Quote
If the cylinder is aluminium it will be Nikasil coated so don't bore or hone it with anything rougher than 240 grit paper with plenty of oil or you will take the coating off and wreck the cylinder. An aftermarket kit is a cheap option to get them running again if one is available. One 125cc CYLINDER BARREL PISTON KIT for SYM SHARK JET MEGALO DUKE SCOOTER 125 cc in Poland if you can wait for delivery

[Edited on 4/4/14 by Peteff]





yours, Pete

I went into the RSPCA office the other day. It was so small you could hardly swing a cat in there.

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AdrianH

posted on 4/4/14 at 02:12 PM Reply With Quote
I did get one of the barrel and piston kits as mentioned, but they do not match the engine as the head stud holes are in the wrong place, the gaskets do not match etc.

This is what I meant by I have the uncomman engine. They seemed to have been made in Taiwan or china and in the early days had different blocks/heads etc.

All the parts you can get either Poland or Durham are for the more common engine.

As they are all built into the main aluminium casing housing geabox etc. getting one that matches as various engines have various ways of mounting in the frame.

I will get there. The response from MikeRJ is probably why I was confused over the gasket, as it does just look flat now.

Cheers

Adrian





Why do I have to make the tools to finish the job? More time then money.
Build diary at http://www.tamarisktechnicals.com/pages/roadster.html

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Peteff

posted on 8/4/14 at 12:29 PM Reply With Quote
I had an old moped which I couldn't get parts for and I cut a head gasket from an aluminium tray that came with food in it from the local freezer shop. It worked for years and was still going well when my friend bought it off me.





yours, Pete

I went into the RSPCA office the other day. It was so small you could hardly swing a cat in there.

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