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Conversion of M50 head to ES2 spec

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Conversion of M50 head to ES2 spec

Posted by steven lewis at June 11. 2017

Hi, just finished off a small project to convert the M50 Alloy  (59-63) head to ES2 500cc spec.

A little involved, remove valve seat, re-machine combustion chamber, then fit new valve seats. and there you have it a much desired ES2 alloy head.  Enjoy the pictures.

Attachments

Re: Conversion of M50 head to ES2 spec

Posted by Dan Field at June 11. 2017

Nice work!

Re: Conversion of M50 head to ES2 spec

Posted by John Oldridge at June 12. 2017

 Hi Steven

​Looks a good job, I didn't realize what  the difference is between a M 50 and the ES2!............what is it? I have just had a spare head done up by Mike P (seats valves springs etc)  Should I have had it converted to ES2 spec? 

On the head I removed, I Intend to get the inlet manifold re-welded so it lines up with the hole between the oil tank and battery box  to enable an air filter to be fitted, as my next project.

​I suppose your bike is an ES2..........Mine is a 1960 (Slim line) M 50

​Regards John O

Re: Conversion of M50 head to ES2 spec

Posted by michael_sullivan at June 12. 2017

John O:

That is a lot of work just to get an air filter.

Have you tried sourceing one of the factory optional air filters?

PN: 18684 ??

Anyone have one of these?  Or a photo of one?

Mike

Re: Conversion of M50 head to ES2 spec

Posted by John Oldridge at June 12. 2017

Hi Mike

Yes I agree, its a ridiculous amount of work, but as yet I have never seen a M50 or ES2 with an air filter!  I have checked as many posts as I can and have never even seen a good picture of one that I can copy.

The problem is the small gap between the carb and oil tank,

sorry to go off topic on this

Regards John O

 

 

Re: Conversion of M50 head to ES2 spec

Posted by steven lewis at June 13. 2017

Previously John Oldridge wrote:

Hi Steven

​Looks a good job, I didn't realize what  the difference is between a M 50 and the ES2!............what is it? I have just had a spare head done up by Mike P (seats valves springs etc)  Should I have had it converted to ES2 spec?

On the head I removed, I Intend to get the inlet manifold re-welded so it lines up with the hole between the oil tank and battery box  to enable an air filter to be fitted, as my next project.

​I suppose your bike is an ES2..........Mine is a 1960 (Slim line) M 50

​Regards John O

 

Hi John,

I converted the M50 head to ES2 due to the fact that the ES2 heads are impossible to find. and i wanted to build up and es2 from my M50...Head , barrel and crank was required. to convert it.

The M50 head needed the combustion and spigot recess increased, the inlet drilled out from 25mm to 28mm. "they are the same casting". To do the combustion you require a CNC mill and a few hours in the machine....not a quick job.


Cheers

Steve

Re: Conversion of M50 head to ES2 spec

Posted by Neil Wyatt at June 13. 2017

I have a 19S head I need to convert to ES2 spec. Not sure if the long inlet manifold is a good idea? Shame though to mess with original parts but as said, you just can't get Alloy ES2 heads any more. Before that sword comes down: I wonder how far off the club is from having a large batch of heads made? (Or even a small batch?)

It was good to read that AN are looking to make 600/650 barrels!

Re: Conversion of M50 head to ES2 spec

Posted by Ian MacDougall at June 13. 2017

Is there a difference between ES2 & 19S heads? According to my parts books it is the same part number for both models. M3T/136 for '56, D3T/136 for '57. Even the cylinder head sleeve nuts are common to the two models although I have seen pattern sleeve nuts described as having ES2 & 19S variants. The carburettor adaptor (inlet manifold) is unique to each model, but as that screws into the head it would be easy to swap that over.

Ian McD

Re: Conversion of M50 head to ES2 spec

Posted by steven lewis at June 14. 2017

Previously Neil Wyatt wrote:

I have a 19S head I need to convert to ES2 spec. Not sure if the long inlet manifold is a good idea? Shame though to mess with original parts but as said, you just can't get Alloy ES2 heads any more. Before that sword comes down: I wonder how far off the club is from having a large batch of heads made? (Or even a small batch?)

It was good to read that AN are looking to make 600/650 barrels!

 

Not sure of the spec for the 19s head, the ES2 is 39mm combustion depth from head face, 79mm across, with a spigot diameter of 92mm. Its easy to remove material from the head, a lot harder to add.

Cheers

Steve

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