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The lack of ability to rotate the engine and the gap at the valve with the shattered bucket make this sound like the valve is stuck and contacting the piston.To remove the head, which sounds like the next step,you'll have to get the cam chain off at the very least. Rotating the engine to the specified position relieves tension on the cams from the valve springs and is correct BUT in this case I think I'd back the cam chain tensioners off (see manual) and then disengage the chain from the cam sprockets. Be sure to tie it to the frame. At that point you can carefully (several stages and in a crosshatch pattern) remove the cam covers.
 

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Discussion Starter #22 (Edited)
Much appreciated thank you. I've removed both camshafts and followed all instructions to remove cylinder head, but it won't budge so I've got some more to do. (The instructions assume you've already removed the engine.) I'm starting to lose confidence in my will power! 馃槀

Cam chain tensioner removed altogether, and looks like I'll have to detach a hose from the carb and then both the intake and exhaust attachments.
 

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Yes, the carbs and exhaust need to come off. There are some small bolts that attach the head as well as the 4 large ones so be sure to get them all. The manual will show the engine out of the frame but it's not necessary to do that to remove the head. Congrats on getting the cams out, how did they look? The covers and the cylinder head together make the bearing surface for the cams and they need to be scratch free. Look also for damage to the cam lobes especially on the valve with the broken bucket. With all the bolts out exhaust and carbs off I've found the some taps with a rubber mallet help to jog the head loose. Be gentle, and take your time. If your will is going away, take a break. Your really almost there. If it turns out to be a stuck valve your going to need to do all this anyway to make room for a new head. Offer stands.
 

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Yes my manual has arrived hooray! I've managed to turn the engine but only about 200 degrees and back. The manual says line up the "|F" line for the back cylinder when removing but "|R" line when inspecting tappet clearance? I could not turn it to find "|R" so was using "|F".

The readings: the inlet valve with the broken tappet has not fully sprung back out so all feeler gauges simultaneously fit! It's partner I can't even fit the 0.05mm gauge between. Same as it's adjacent valve on the exhaust, then 0.73mm on the other exhaust valve!
Pretty sure that means you have a bent valve.

Piston hits it as it rises and the engine won't spin further.
 

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Discussion Starter #26 (Edited)
I've taken the cylinder off and you were right: two of the valve heads have snapped off and one is rammed into the piston head!! The cylinder doesn't seem to have the slightest bit of damage though! I've got a new piston on order.

Since the piston is not fully out (presumably because the engine wouldn't turn to the correct position previously) I don't think it's possible to get the piston pin out, so I guess I'll just turn the engine until it's lined up properly. Am I best putting the head back together first (with cams lined up), then turning it?

And Trundlebike7: Thank you again for such a kind offer. I managed to find a head 20 minutes away for 拢20 so I bit his hand off, but thank you.
 

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Glad it's working out for you. That's a lot of destruction. Would be interested to know what the valve clearances are for the other cylinder. Have to wonder what happened and I'm wondering if the clearances tightened up leading to a slightly open valve, overheating and seizure.
 

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If you'e just trying to get the piston off the rod you can rotate the crank without having to put anything back together. Since you have the cylinder off just rotate the crank with one hand while you support and guide the piston with the other. Some rags to keep the wrist pin clip from dropping into the cases and some heat on the piston if necessary to make the wrist pin easier to remove.
 

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Discussion Starter #29
Great thank you. It's certainly done some damage! (See photos.) I rotated the crank (freely) and got the circlips out, but I couldn't get the pin to budge (and wasn't sure how much pressure to apply, with a hammer!) so I'll try with the heat. 馃憤 Everything below the piston seems fine though. And I could check the clearance on the front. (Difficult to jump at the idea of further work when I thought I was about to be finished! But if they might be the cause - and since your advice has always been spot on - I'm happy to seize the opportunity to learn more! 馃槀) I'll update...
 

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The only reason I was curious about the front was to see if maybe this was a case of too long delayed maintenance, that is, valve clearances neglected. Would be nice to have at least a theory as to why this happened. No need to worry about it now, but of course you'll have to check them all before you're done. As for being spot on let me just say I appreciate your trust.
 

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The only reason I was curious about the front was to see if maybe this was a case of too long delayed maintenance, that is, valve clearances neglected.
This engine blew up within one mile after being purchased. That seems too coincidental to be due to deferred maintenance. More likely, the previous owner was inside the engine and jacked something up.

The valve train on the SV are very stable. We've seen many reports of bikes going 100k+ miles without needing adjustment.
 

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Great insight thank you as I drastically overfilled it with oil! I wasn't thinking and was checking the oil level window while it was on its side stand! hangs head in shame I emptied over a litre!
The oil was checked on the side stand, and then over 1 litre of oil put in when potentially the oil level was already correct, would this possibly have caused the issue or do these bikes cope with being over filled ??

Sent from my SM-G960F using Tapatalk
 

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The oil was checked on the side stand, and then over 1 litre of oil put in when potentially the oil level was already correct, would this possibly have caused the issue or do these bikes cope with being over filled ??

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From all the posts I've seen these machines do NOT like being over-filled. I keep mine @ the mid-way point and check when on level ground. I sometimes just use my Smart phone in one hand to take a quick picture whilst straddled on the Bike to check and if OK then delete.

I do however also know what the level should be when my SV is on it's Rear Paddock-Stand.

HTH :)
 

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Discussion Starter #34
I've only gone and done it! Went out for my first ride yesterday, and isn't she a dream?! Wow!

Sadly I've given myself an oil leak! It looks to be the cam chain tensioner on the head I changed (rear). The bolts that attach it seem plenty tight, but the adjustor nut in the middle will not tighten - it just winds and winds - and I didn't replace the gasket.

Thank you again for all your help.
 

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Discussion Starter #36
Made myself a gasket for the cam chain tensioner which has improved the oil leak loads, but there's still a small leak which I'm hoping will be solved by replacing the tensioner, when it arrives.

The clutch was slipping a little: when I release the lever it doesn't properly engaged gear for perhaps half a second. (That horrible sound and feel of an automatic car.) I didn't notice this at first, so I wonder if it developed as I rode (which can't be good). I wonder if I just need to adjust the biting point, but I'll check and see what the manual says first.

I heard a noise like I'd dropped something at one point and a second or two later I lost power. By the time I'd walked up the road to check I hadn't lost anything, it then started again no problem. Nothing to worry about?! 馃槀 馃槼

The throttle is quite stiff to turn (particular versus my 125). Is that normal/correct? It's got dodgy foam after market grips too. (Apologies if they are factory fit! 馃槀 I love them really!) Thanks.
 
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