Smashed Valve Collar

[BagONails]

This was an unpleasant but fortuitous finding yesterday. When I started dismantling the rocker covers, head steady etc. thinking to reseal the RB, then through the front LH exhaust opening I spied this nasty looking object and let a few expletives fly. The rocker box was next off very carefully and I found a loose piece lying on top of the head. Putting this to one side I continued the frantic hunt for more shrapnel. At this stage I was using a small magnet on a stick, ha ha I had no idea they are aluminium!  Needless to say I didn't find any more with the magnet...Then suddenly I caught site of something lodged in the RH exhaust oil drain hole and after removing the cylinder head this was retrieved. As you can see I appear to have got it all which is a big relief, that and the realisation they are ally which kind of reduces the damage potential I think.

Now it gets interesting as I'm wondering what on earth has happened here. Initial investigation shows the fatigue lines coinciding exactly with the outline of the spring, makes sense being the high stress/load bearing area but I've never seen this happen before. Would love to hear from you guys if this is a known failure mode, I have had a search and didn't find anything on the forum.  I have now measured the spring wire diameter and they are all the same but then noticed what I initially took to be an optical illusion but now know by measurement that this LH exhaust outer spring is different to the other three. The gaps between the coils are 1mm smaller i.e. I think it has more coils.  If this spring has been binding, no wonder the rocker box was leaking a bit!

I am now tearing the head down as I think possibly all the caps should be replaced but maybe not if this spring is incorrect, anyway we shall see...Now I'm off to cobble together some form of valve compressing lash up to get things apart. 

[groily]

Hmm. That spring is very different from the others and looks as if it might very well have bound to me (and caused the grief - something had to give). Hope the pushrod, rocker and follower are OK.
Think the PO needed to get his eyes tested frankly.

Good luck with sorting it BoN, hope 'just' a spring and cap replacement

[Triton Thrasher]

At this stage I was using a small magnet on a stick, ha ha I had no idea they are aluminium

Are they supposed to be aluminium?

Steel every time for me.

[JulianS]

First thing I would do is check the fitted length of the valve springs, maybe just me but the coils do look crowded on both exhausts. Should be outer 1.312 inches according to the books.

Possible that the setup is a home made conversion to allow the use of Gold Star progressive wound springs? Like the Eddie Dow conversion from the 1960s or the similar Ebor Motorcycles conversion though your collars don't look as substantial as these?

https://eborbikes.com/index.php?route=product/product&product_id=56

Photo is of my A10 head some years ago with the Ebor parts.

[chaterlea25]

Hi All,
Those valve caps look to be compressing the springs more than those in Julian's photo?
I have not seen alloy caps that mimic the steel type with the " upstand" in the middle.
Usually  the alloy cap conversions use different collets than the SR alloy head type
So be warned.
I would replace them all with standard SR parts.
Autocycle are listing the hard to find SR collets
on eBay.
I would check out the cam and followers for any consequential damage

John

[berger]

i agree with john about checking the cam and followers it looks like that spring could have been bound up hence the damage, when i did the dry build on the berger build engine with high lift cam i spent lots of time making sure all the springs had clearance when the valves were fully open because the inlets are super rocket and the exhausts standard A7 i had to skim the bottom keepers down to get sufficient clearance, i seem to remember a post on here about a wrecked camshaft maybe someone else knows, i've been to the pub since then

[bikerboy]

I would also agree with chaterlea25 new SR parts all the way for me dropping a valve would prove extremely costly

[limeyrob]

I seem to recall ally valve collars were a cheap common accessory sold to reduce valve float at High revs, but I also seem to recall they had a habit of having the valve collets pull though.  Stay with steel.  A close call!

[Triton Thrasher]

I seem to recall ally valve collars were a cheap common accessory sold to reduce valve float at High revs, but I also seem to recall they had a habit of having the valve collets pull though.  Stay with steel.  A close call!

They were the sort of go-faster goodies that were a sales success because the enthusiastic owner was already in the habit of decarbonising the head and pistons and grinding-in the valves, so was capable of fitting replacement valve spring retainers.

Same could be said of the kits of rocker shaft shims and the alloy valve adjuster locknuts.

[Swarfcut]

 Teaching your granny to suck eggs.....

 I've seen cheap valve spring compressors bent by the force needed to overcome the grip of long standing valve collets in the valve caps. All it needs is a bit of tension on the compressor, support to the pusher on the valve head, and a good smack with the hammer on the compressor arm adjacent to the cap fork. This will break the spell between the collets and the cap. The rest is easy, even the Chinesium type can compress a spring, just needs a hint of violence to break the seal.

 Swarfy.

[BagONails]

Great responses, thanks to all for your helpful comments.

I should say now that this turns out to be a Shooting Star head on 650 bottom end so I have no idea yet how much of this lash up is standard and how much is cobbled together with nefarious parts.  Needless to say I shall be checking everything and have already found other anomalies. I too was amazed to find alloy caps!  Since then I've been looking up the parts online and found 67-0034 caps (Parts book says correct for all models except SR) at SRM that appear to be steel, Draganfly turned up steel with an alloy option for less money! I'm even starting to wonder if PO turned these caps up himself because they don't look like anything I've seen in all the usual places...

Its Beezer Club night tonight so I shall transport my bits down there and see what the locals have to say too.

Pretty much resigned now to lifting the barrels as well to properly check everything. What I can say is the bike has covered probably around 3000km or thereabouts with me now and was running well! I have turned the engine over in the past with the plugs out often by hand and never been aware of a tight spot so I'm hopeful the cam and follower has not suffered...perhaps the spring coils were just kissing together but even this at 3000RPM doesn't bear thinking about does it!

Swarfy, yes I'm with you mate thanks. My VSC is way to big for this so I'm using a G clamp and have turned up a nice piece of tube which I will cut a window in the side so I can deliver the required violence to crack things loose...we shall see...

More later, hopefully not too much more aye.

[berger]

BoN out of interest just check the push rods for boomerang shape if all is good and the cam isn't chinesium or spanish 24 horrors ducati soft your cam and
 followers could be ok i hope

[Swarfcut]

 If you can make do with a cast iron head, a used, complete unit could be a quick answer. Certainly the alloy head has a value if you can bear to move it on. Cast head , wide fin casting, number 67 1066 should do for now. Sure, fitting it is half the battle, as it was in 1066.....

 Swarfy

[CheeserBeezer]

FYI, the Shooting Star, generally speaking uses the same valve arrangement as the iron heads. The 650 alloy heads use their own valve, spring, and collet arrangement. I've never put a Shooting Star head on a 650 but I know it's something that a lot of people do without problems. I'm assuming that, if using the SS head, you should still use the SS valve parts. Others who've done this mod will be able to chime in here. Looking at your pictures, it looks like the PO has used 650 alloy head valve parts on the SS head which, I would have thought, are incompatible.

[Radlan2]

Hi, A Shooting Star head can be fitted to an A10 using its original type valves, caps and collets which are also the same as fitted to the iron head 650. I have done this setup using the 356 cam and valve size can be increased using larger iron head 650 valves. The valves, cap and collet arrangement you have there is for the the 650 alloy head annular groove type and was not used on the 500. Also if the higher lift "Spitfire"357 cam has been fitted it would make it more likely to become coil bound along with the mismatched springs. I don't know if the Spitfire cam has been used with the 500 head but it would require special modifications. As mentioned Ebor bikes have some info on there website which might help.
          Best Regs
                   Chris