Dropped valve cam removal

Paul LeClair said:
when my RGS motor hydraulic locked from fuel the cylinder full of fuel fired a valve up into its shim bucket hard enough to bulge the shim bucket substantially
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I remember the pictures Paul. It's interesting to work out how it might have happened. Obviously the valve was open, but not fully open because the cam lobe would have to have been on the edge of the bucket to allow the valve to push the centre of the bucket up. But how? I'd have thought the valve being open would relieve the pressure of the hydraulic lock. The only conclusion I can come to is that the partially open valve didn't allow enough of an aperture for the amount of liquid trying to get through, and the liquid pressure in the cylinder built up to the point where it forced the valve onto its seat while the cam lobe was still trying to hold it open. There must have been some enormous forces involved to slam the valve shut and bend a rod. You're lucky it didn't pull the head studs out of the crankcase.

Cheers,
Cam
 
I certainly agree with Phil that a chain breaker is the best way to disconect the chain, but I would not be running that motor again, without a full bottom end strip and a very through wash out of all parts including oil gallerries and the oil pump pluus all gearbox and clutch compoinrents and the starter clutch side as well, everything in fact.Not so doing, would not inspire confidence.
CLEM
 
Hope my comments did not indicate I thought it could just be put back together and run.  After such a failure complete disassembly is the only option, to allow proper inspection and cleaning.

But Paul's comments show that even with a catastrauphic failure elsewhere, the bucket should never crack like the one shown.  I am pretty sure Allan has some incorrectly manufactured aftermarket buckets.  Whether it failed due simply to being too brittle, or as a result of some other engine catastrophe, will only be found out after disassembly.

A broken valve spring will not usually cause any major dramas as shown, often the motor still runs fine at moderate revs, with some odd ticking noises here and there.  Funny though that it looks from the photos like the shim is riding up against the cam lobe, when with the bucket gone it should have a gap of around 2.5mm.  That would tend to indicate the collets have dislodged and the valve has indeed dropped... hope not.  If the valve nips up in the guide I think it usually spits the shim out, which does not appear to have happened here.

As for the chain, yep, breaker is the go, but given the whole thing is to be stripped and cleaned anyhow, a carefully used grinder will suffice if that is all that's available.  Getting the cams out without breaking the chain would I think be impossible due to the through studs, unlike many Jap bikes with bearing half-caps and bolts.

All the best Allan, have been where you are.  We'll all be on line for moral and other support.  It's worth it when it all goes back together and runs better than ever.

Cheers
Steve B
 
I agree entirely with Steve B's comments.

In the case of my RGS engine, to cut the cam chain I used a Dremel with a cutting disc, made very quick work of slicing through the chain. No debris into the engine, just stuff the cam chain tunnel and cover the cams etc. You are not going to reuse the cam chain anyway after such a trauma to the valve train and cam chain

I swear there was a sigh of relief from the engine as I unbolted the cams after I cut the cam chain........

in my own situation, I did a full bare cases strip as I had to pull the crank out to send it for a rebuild with new rods and bearings, hopefully you get much luckier and only have to deal with repairing the top end, although you should give serious consideration to a full engine strip just to be absolutely sure there are not any surprises lurking in the bottom end, but I guess you make that decision after determining what caused the engine to lock up. The good news is that anything is repairable.......

Paul LeClair
 
Well Paul, I went the Dremel way too, as you say very little mess. With the help of a couple of mates, we got the engine out and in to the conservatory, at least it will keep the SF engine company.
Once the head was off we found that, the valve head had come off and bounced around a bit eventually knock a large hole in the top of the piston, the head has some damage to the skull and valve seat, why it's come off I haven't figured out yet. I still need to strip the head. The rod looks OK, but I need to check properly. The piston is also cracked a bit and there is some slight damage to the bore. The motor looks like it has been apart before and the head and barrel came off easily. So a bit of searching for replacement bits and tot up the cost.
Any suggestions on how you think this could have happened appreciated. Andy I'll be in touch soon re a new cam and primary chain.

Al
 

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Ouch Allan, sorry to see that.  Obviously, under normal circumstances they should not do that.  ;-)  Valve heads are often friction welded onto their stems, which is presumably your failure point.
I am still very suspicious of your valve bucket, which should never crack like that (witness Paul heavily bending his one but it did not crack).  It's possible that the bucket disintegrated and while there were some fragments floating around between cam and shim the valve was jammed open, and then hit by the piston, initiating the mess you see there.  Just a theory. 
Otherwise it's just a straight out valve failure, either due to a rogue valve from an otherwise good source (unlikely), or poor quality valves which could not handle the application (likely), or perhaps a valve that had some previous trauma and reinstalled (people do the strangest things dept.).
If you have some measuring equipment (degree wheel, dial indicator or stop), you might want to check your crank phasing before you pull the cases apart to inspect the bottom end.  Should be ok but worth a look.
Cheers
Steve B
 
Interesting thing is the it's the exhaust valve that's gone and the inlet that has the mashed bucket. I reckon the floating valve head or large lump of crown got between the piston and inlet valve when closing and gave it enough of a nudge to smash it. The exhaust one, on the other hand had a a slight bulge in it.
Thanks for the tips on the crank and rods, I am a little concerned on the condition of the bearing in the big end, but it seems smooth enough to move on the journal.
Al
 
Hmm ... I don't think I'd do the head in the oven thing if that happened to me - my oven is electric.

Look at this event as an opportunity rather than a disaster. While your at it you may as well do a Paul LeClair job and lighten the crank, fit Carillo rods, big bore low friction high comp slipper pistons, etc. :D

Cheers,
Cam
 
Mr Cox has sn RGS head on ebay. Expensive but maybe a better bet than trying to sort a damaged one out.
 
Thanks Pat, I'll have a look. The wife is in dispare with me already. "Bloody thing is costing more than a new bike" and now she has lost most of the space in her conservatory, with Laverda engines. She says, it's a good job she is so understanding.
Al
 
It would probably be better to contact him direct Al. I believe he has a lot of RGS parts
 
Allan,

Malcolm has an RGS in for breaking that he has not had a chance to start on yet.  As Pat says, it would best to contact him direct and with a shopping list - sure you would get a much better deal that way.

Best of luck with it, Andy
 
Hi Al

ouch is right!

good news is it is all repairable, and fairly economically.

I had to replace one cylinder liner in my RGS"1200"  engine that bent the rod. Turns out replacing the liner is inexpensive and surprisingly easy, but then there is a cost to machining/honing the new liner to proper clearance for the replacement piston, so a full used engine cylinder in good shape might make economic sense, same with a good condition used head such as Mr. Cox is presently offering on eBay. At this point I don't think I would trust ANY of the valves or valve buckets presently in the exisiting head, you don't want to fix only the existing damage and reuse the remaining valves and buckets, only to have it happen again later on another cylinder........

I suspect there is a really good chance your crank may have escaped unscathed, with the piston/valve having given way so significantly rather than the crank being damaged, but obviously at least the crank phasing should be carefully checked just to be sure, and the engine needs to be thoroughly cleaned and flushed of all debris.

I laughed at your photo of your head in the oven, but the photo looks like it is an electric oven...... :o

Paul LeClair
 
Well as they say, it never rains it pours. Turns out the con rod is bent too and it has a tight spot on the journal. So acting on your advice. I put some bids in for some of the parts Mr Cox had on ebay and fortunately have been successful in obtaining a crank, barrel pistons and head, he is only 20 mins away, so had a look prior to bidding when I picked some other parts up I had won earlier. Toting it all up, it was borderline between repairing or replacing, but by replacing, I hope to get her back on the road for Lemonjelly's bash in a fortnight.
I must say Malcolm is an absolutely top guy to deal with, so would recommend him to anyone without hesitation. So we'll be popping over in the morning to pick it all up, then a run over to Slaters for a full gasket set and fuss the dog.
So hopefully meet some of you at the Culm Valley doo.
Thanks for all your comments and support. It's much appreciated.  :D :D :D
Cheers Al
 
get your gaskets from Classic Gaskets also known as Brancanto engineering Tony and Donna Brancanto),or Giovani Moto  Giovanni carrusso) you will get the full set,and made by Centauro (same as factory) which includes both sizes of cylinder base,(1000/1200)  valve stem oil seals, copper compressible exhaust gaskets and all O ring, oil filter, dip stick, carb manifoilds etc, ask for a gasket set and an oil seal set.
The Laverda dealers tend to only selll seperate items which is a pain in the derrierre.
CLEM
 
CLEMTOG said:
get your gaskets from Classic Gaskets also known as Brancanto engineering Tony and Donna Brancanto),or Giovani Moto  Giovanni carrusso) you will get the full set,and made by Centauro (same as factory) which includes both sizes of cylinder base,(1000/1200)  valve stem oil seals, copper compressible exhaust gaskets and all O ring, oil filter, dip stick, carb manifoilds etc, ask for a gasket set and an oil seal set.
The Laverda dealers tend to only selll seperate items which is a pain in the derrierre.
CLEM
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Clem, I had to laugh at this, and there's you with your arm around Richard Slater in your avatar photo!  :D
 
AndyB said:
CLEMTOG said:
get your gaskets from Classic Gaskets also known as Brancanto engineering Tony and Donna Brancanto),or Giovani Moto  Giovanni carrusso) you will get the full set,and made by Centauro (same as factory) which includes both sizes of cylinder base,(1000/1200)  valve stem oil seals, copper compressible exhaust gaskets and all O ring, oil filter, dip stick, carb manifoilds etc, ask for a gasket set and an oil seal set.
The Laverda dealers tend to only selll seperate items which is a pain in the derrierre.
CLEM
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Clem, I had to laugh at this, and there's you with your arm around Richard Slater in your avatar photo!  :D
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Well, I am glad that has been cleared up. All this time I thought it was Richard and his very large and mannish wife.  :-*
 
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