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Discussion Starter #1
OK, call me a wally, but after working on desmo valves for over forty years, I've made a beginner's mistake and let a valve drop into the cylinder.

What's done is done, but my question to anyone who has done it - is there a simple and quick way to remove the rear head with the minimum amount of work?
 

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I'm not sure how to answer your question directly, but I do recall reading a post somewhere in which a gent had done the same, and somehow managed to get the valve back into the guide without disassembly.

If I can find it, I'll post a link, but if I were you I'd spend some time googling. I think it was a Ducati forum, but if one guy has done it successfully, probably others have as well, so search far and wide.

Might save an awful lot of work. Or it just might mean a lot of time spent trying, and not succeeding, and disassembling it anyway....

Good luck, and please let us know how it works out.
 

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I was thinking along these lines... with the super strong rare earth magnets available these days it would be pretty easy to make a snake to grab the end of the valve and pull it back up.

Might need a plastic tube to keep the tool from sticking on the way down... and if you need visibility there are cheap boroscopes out there these days too (less than 20 bucks).

I'd certainly try this before resorting to pulling the heads.
 

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The simple "ounce of prevention is worth a pound of cure" fixes are to always put the piston on TDC before pulling the collet or keep a length of clean thin rope handy that can be stuffed down a spark plug hole to fill in the cylinder while leaving enough sticking out the plug hole that it can be safely pulled out after the valve is once again secured. But you already knew those tricks from working on that bevel for decades. Good luck with the cure.
 

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That was the video I was referring to--glad someone else remembered it.
Brilliantly done.
Good luck.
 

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Discussion Starter #7
Thank you guys for the replies! I will have a look this morning, but all I can see through the spark plug hole is the head of the valve laying sideways, I can't see how I would be able to get hold of the stem, but who knows? What is bloody annoying was that when it first happened, the end of the stem was still in the bottom of the guide and maybe I could have gently turned the engine to hold it in place, but I was dead scared of bending the stem.

To hold the valve up during adjustment I use a piece of bent welding wire, which has worked for 40 years, but yesterday the wire must have twisted enough to let the valve drop past it.
 

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he's only got a 7mm hole. maybe a little needle roller style magnet piece in the end of some very thin rubber hose?

the magnet linked above used through the plug hole for stability would be a good idea. i'd be trying real hard to not drop the motor.
 

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I tack-welded a magnet onto the end of a length of rebar tie wire, quite bendy without breaking, strong. I dropped a half-ring down an oil passage years ago and wanted to get it out, I ordered a very small-diameter magnet, I'm sure it's <7mm. YMMV, I'm not a welder so have no idea what kind of bond I've got but I've used it a few times and it hasn't fallen off.
 

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Discussion Starter #12
Update: I've ordered some 5mm dia magnets (which is what I should have done when it first happened) and a pair of forceps. I'm hoping that the magnet will be able to grab hold of the valve tip while I use the forceps to ease it into the guide. It may be possible to grab the valve through the inlet port if all else fails. This only happened because the 7mm collets are so fiddly, you wouldn't believe how much easier 8mm ones are to hold.
 

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Discussion Starter #14
Update: please don't laugh. I araldited the magnet to a length of steel rod and tried to replicate what the guy in the video manged to do, but after spending ages, it is apparent that it is impossible to get the valve lined up with the guide; the head is too heavy and the forceps are useless because there is not enough room in the spark plug hole to be able to move them with the valve in the jaws. To make matters worse the magnet has detached itself and is now stuck to the valve! Quite how it found the valve stem more attractive than the araldite/steel rod combination I'm not sure. I reckon that the guy in the video still had the valve in the bottom of the guide. I've been unlucky in that if the piston had been a quarter of an inch higher the valve would not have been able to drop out.

So now it's head off time but I've never dropped a belt engine out of a frame and have no idea how to do it. In the factory they stand the engine on a stand, drop the bare frame over it, bolt on swinging arm, forks and wheels, fit the wiring loom and hey presto, but what about in reverse? how much will I have to unbolt before I can get the engine out? I have seen pictures of someone working on a Supersport and they ran ropes from the roof to under the seat loop and hauled the rear of the frame up, but my garage roof is flimsy and won't support that.
 

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Discussion Starter #16
The beast lives again!

Removed air filter, pulled injectors off their stubbs and placed to one side of the frame, removed offending inlet stub. Pushed steel rod with magnet attached down guide, aligned top of valve with magnet, then holding valve stem with forceps, managed (after a lot of swearing) to get tip of valve entered into guide. Rotated engine gently to raise piston enough to keep valve in position, then by hook and by crook and juggling magnet and forceps, gradually eased valve up through guide. Unfortunately, the piston can only be raised a small amount before the slid-over rocker begins to bind, but by then the valve was aligned and so I was able to use the magnet to pull it all the way up.

Lesson (if anyone else is stupid/careless/unlucky enough to suffer the same fate) if you do drop a valve and it is still engaged in the bottom of the guide, leave alone! Don't touch anything until you can devise a magnet on a rod which can be used to hold the valve in position; the hardest part of the rescue is getting the valve stem located back in the guide.

I've had a week's holiday this week and I've spent almost the whole week engaged on engine work. On Monday I adjusted the valve clearances on my Honda Jazz and as anyone who has done so will tell you, it is a hell of a job, involving stripping half the car down just to get to the rocker cover. At least the GT1000 was not as difficult as that. I think that I've earned a beer. Thanks to those who chimed in.
 
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