C15 Engine Bracket.

Started by Barnsey, 29 Dec, 2025, 14:03

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Barnsey

Hi All, and a Merry Christmas,

   All the pictures of C15s which I have seen have a bracket from the top of the cylinder head to the top tube of the frame.  My bike lacks this, so I bought one from Ebay.  The holes on the flange are correctly spaced to fit on the head bolts, but it isn't obvious how to bolt it to the frame.  Should there be a fitment welded to the frame to attach it to? 

   BR,  Ian

Barnsey

Here is a screenshot taken from Hugh Ferrier's video.  But I can't quite see what the bracket is bolted too.  Maybe there is a bit of rubber to damp out the vibrations. 

Barnsey

Actually I am answering my own question here.  The 'Head Steady Bracket'  is bolted to the 'Head Steady Clip', rathern like a big P clip.  I ordered one from Feked.  Next I need to figure out what size nut and bolt to use, but it doesn't look to be too critical. Even a metric might do (shock horror spit!)

rhyatt

Don't forget to order the little arm that goes between the head steady and the P clip
Or make one from a bit of strip .
I think Feked do them about 3 quid

Barnsey

Thanks for pointing that out!  That just cost me a second lot of shipping, but never mind.


Barnsey

I note that the arm is missing on my second C15, with the cylinder head bracket bolted directly to the 'P' clip.  Maybe this is something I can put right some other time when no 1 bike is together. 

In the mean time, should the P clip be in front of the bracket or behind it?   

rhyatt

#7
The link to Feked above I sent you gives you the connecting link between the P clip and the head steady.
Double check the 4 nuts the hold the head steady to the rocker box studs , 2 are 1/2 nuts and 2 are normal.
Front or back , from memory once the P clip is on the top frame , it's location is self-evident

Barnsey

Yes, I have the link, but does it go in front of the bracket, i'e towards the front of the bike, or towards the back? 

  I take it that there should be 5/16" cylinder head nuts with the bracket on top of these and the half nuts holding it in place? 

  If you look at the photo, I reckon that there might just be enough length of head bolt for the half nut. 

  I bought the second bike in the hope that it would answer some of these sort of questions, but it seems that I could have three bikes and they would still all be different   }:(
 :o

rhyatt

My own P clip is at the rear of the head steady on my SS80(which is pretty original.
My sons c15 it is at the rear also ( but I just cut a short length of flat strip for that link)

Barnsey

That is helpful, thanks!  Now I just have to wait for the postman. 

rhyatt

Just looked again at your picture , you only have 1 x stud nut done up.
Bear in mind the valve springs are trying to lift up the rocker box , so I'd ease off the adjusters or do up the 2nd nut until you get the 1/2 nuts sorted

Barnsey

In the photo the nuts were just loose.

   Can I just clarify, the cylinder head nuts go on first.  The bracket sits on top of those, and then the half nuts hold the bracket on?  Is that right? 

  I ask, 'cos that is how it is on my other bike and on Hugh's video.  However on this bike that results in the bracket jammed against the top tube of the frame.

The bracket is 2 1/2"  tall.

Also there is not enough thread on the left stud to put a half nut on. 

  SO, I might have to put the bracket under the cylinder head nuts, and run like that, but this seems a bodge and I don't much like bodges. 

Barnsey

Here is the screenshot from the Hugh video. 

Barnsey

Here is an updated photo of my bike no 1. You can see that the studs are too short and the top of the bracket touches the frame. 

  On my other bike there are two full size nuts on each stud, one above and one below the bracket. 
The bracket itself looks to be the same size, not easy to tell without removing the tank,  but it is also slightly to the side of the frame. 

  All of which leads me to wonder if there is something odd in the engine.   Might the cylinder barrel be longer than it should be for a C15?  I might have to take some measurements.  .