Valve seals job - bloody stiff exhaust valve springs

They had these cylinders for a similar price a few years back. They had them in stock for quite a few years, but eventually they disappeared. I got one for my 400NA, about 2010 I think. Unfortunately, a couple of years ago a little end seized, the piston picked up on the bore & made a bit of a mess of it. I got the original rebored & fitted it with o/s pistons, but I've still got the 'new' one, and now I've seen Dave's piece on swapping liners, I may be able to do something with it

i would take top off and have a look better tobe sure than do more damage and end up with a bigger bill

Yes,it was all tightened before. I have turned the engine over a few times before torquing the head bolts, it was all fine, but obviously the camshaft was not pushing on the valves. Shame, I have not seen anything out of wack, one of the valves was a bit sticky, could have been that, or I do not know. I have turned the engine over a few times since, and it looks like everything works, and because I have turned the engine over earlier without any hickups, I would hope it is not one the rings broken. Do the headbolts survive the 3-3.5 kgm torque easily? I hope one of the headbolts did not crack the crankcase under valve pressure

just be careful taking it down and check everything its not been run so unlikely any thing will need replacing unless you have damaged something

have you tried having a poke around with an extending magnetic pick up tool or a flexible claw type pick up tool if the broken bit is non magnetic, you might be lucky, you can take off the clutch cover and then you can see into the crankcase a bit better and get the pick up tool into the crankcase from the side. If you can get it out without splitting the crankcase it will be a lot easier for you.

It's worth turning the engine upside down, it might fall out. I dropped a washer several times in my 125 engine while trying to slip it on a pin in the depth of the crankcase, it came out each time when the engine was inverted. Failing that, I seem to remember someone posted a long time ago, probably on the old forum, about working on the balance chain by inverting the engine & removing the bottom half of the crankcase with just the side covers removed.

So, I just can not find the damn thing. I bought one of those telescopic things mentioned earlier, and poked around with the magnet inside. I tried to be very thorough, and fortunately the inside is not as much magnetic, as I feared it will be, I poked from the top, moved the rods to the other side, poked from there, from the side, unscrewed the oil plug again, tried from there, went through all the gears (turning the wheel), no issues. After this - probably a good deal of a day went by - I decided, it is not inside, so gambled a bit, put the top end back together, started the engine whilst finger on the kill switch, just in case, than whilst on stand, went through the gears again - this time engine running. No problems arose, so I did a few careful laps around, then some on rougher surface, the engine does not rattle, so I guess I might just have been lucky, and the bit is somewhere in the rubbish bin with all the other crap, that collected underneath the motor whilst doing the rebuild. I do have oil problems, as the plug is leaking - a crack, that was all the time there, but helped by the PO at bay with loads of sump silicone, rubber washer and some JB weld-ish thing, that is thrown on all the surrounding area. Probably could have taken the engine out, turn it upside down, take the lower crankcase off, look inside for the bit and fix the oil leak, whilst at it, but I did not - I really hoped, I will have a working motorbike by this past Sunday (I did not), as I was about to go on a driver's training, I have been waiting for quite a long time. Without the rubber washer under the plug, and the tons of silicone the bike is rather badly leaking oil - a drop every second with a hot engine. I could possibly just JB weld the whole shebang - plug, hole, crack, the lot in, but I don't feel like being such an amateur, and I do not know of any alu welders in the area (and the engine would have to come off). Did anybody succsfully cure a crack, that rus across the threads? I have been told to grind the crack into a v shape, fill it with JB and when just a bit set either screw in the oil plug covered in silicone grease, or remodel the missing thread with a sharp pick, or any other tool. Would something like that hold?