Enya 90 - 4 c exhaust manifold?

[Nigel Dell]

Hi Guys

 

been on eBay again and picked up a forelorn 90 4 stroke, it had been run on castor and was well glued together no sign of after run etc, but with plenty of heat I have stripped and inside is surprisingly good so worth saving and as a whole has cleaned up well just had to replace the bearings, they gunged up rather than rusty so a silver lining there.

It came with a flexible manifold and a silencer from who knows where, normally I go straight to Ken Enya for parts or webbies, well obviously I can’t go to webbies now sadly and Ken is unusually not responding, it shows a flexible exhaust kit and a silencer on the Enya site but no rigid manifold, I managed to get the silencer plus a couple of bits a pieces from RC Japan but again they could not help with said manifold, even just engines are out of the M11-75 manifolds, was thinking of getting thick walled steel tube and making my own, but does anyone know who else I can try for this part please? 

[Paul De Tourtoulon]

An OS .90 fs also has the same threads, 11 x 75, castor is your friend,,,🤣

 

exhaust threads.pdf

Edited December 5, 2024 by Paul De Tourtoulon
castor

[Nigel Dell]

Thanks Paul, I think the 70 too, just got to find stock, I think Just engines one was ASP/SC based so will see if they have the OS one, although the OS ones I have seen are male one end and female the other, I don’t remember them all being like that, as always I need a male either end😳

[Martin Harris - Moderator]

Most APC/SC engines are direct copies of OS engines so their exhaust parts should be interchangeable. 
 

I’m not sure which headers you’ve seen  - all the ones on mine have been double male ended. 

[Nigel Dell]

Yes Martin, Just got to find one, the later OS seem to be M/F just got to find stock, Andrew a JE is awaiting new stock with the re release of SC range they should be around in the new year unless I can find old stock, there should be plenty out there until you need one!😂

[J D 8 - Moderator]

 I was thinking of biding on that one as well being a fan of Enya 4 and 2 strokes.

Do check carefully the exhaust threads in the head. if they have become loose due to the manifold having become loose in flight and worn them down getting it to stay put again is a devil of a job. 

     One of my 90 4C engines has this issue so a flexi to the manifold pipe takes the vibration load off the manifold pipe and it stays in place.

[Paul De Tourtoulon]

Re tap it like I did last week on a Saito .100,,

[Nigel Dell]

That’s a neat repair Paul, thankfully the threads are good in the engine I have, it looked a bit scabby and a tin of treacle inside but it cleaned up a treat and is very good underneath, I take your point on the wear though, it came with a cut down flexible manifold so a fitting one end only, I can get a flexible exhaust all be it long but I think for the longevity of the exhaust threads I like your idea.

I had a route round my boxes and in the ASP 160 twin FS I had two ready to go fs 80 exhausts! 😳 I was doing a twin carb conversion on this engine and totally forgot they were there, it proves those manifolds are ok for the engine if I now go that route, thanks to the size chart you posted I also saw the RCV 58/91 were also the same, the manifolds are still available from Weston, cheap too, I have a 58 and tried that, the angle takes the silencer to the back of the engine not the side but if no other choice would be an ok fix.

You have given a good option there, the engine is too good to be shoved away in a draw so I will ge the flexible manifold for it I think.

[RottenRow]

I’m not sure if the 90 is different (I doubt it), the (original) exhaust on my 60 is a plain pipe, not threaded at all, with the engine end of the pipe belled out. This is retained in the head by a separate threaded fitting and a pair of split collets.

The silencer itself just clamps on to the open end.

The pipe can work slightly loose over time but the thread in the head is not then supporting the loose vibrating pipe (which is what causes the wear in the OS style heads).

 

Brian.

[Nigel Dell]

Hi Brian, yes the earlier ones were and my 60 was like that until I decided to replace it with the new type system and my 53 came with the later type which I found better and not relying on the clamp on silencer, certainly sturdier. This 90 came with a cut down flexible pipe and probably a better bet as I think the extra weight of the new type system might add to the wear problem although I have not come across in my new bought engines I have seen plenty suffer from it.

[J D 8 - Moderator]

  Neither of my other Enya 90 4c engines have had the issue. The most used in my Major Mannock has been fine for over twenty years but does have the benefit some support from the models structure.

[Nigel Dell]

I can see that is see that is very supportive JD, I have never had problems with any of my engines to be honest just with parts supplies getting harder to find it is sad to lose a perfectly serviceable engine.

But on the positive side I will make one for this engine so I have both for it, I have several engines with this fitting, also an interesting point Tim at Model Shop Leeds replied that the OS 70/91 part is now discontinued and once the SC spares start coming through at least that will be a supply replacement though it is not showing as a replacement part yet. I hope this may help anyone else in the same boat.