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Post by dreamer on Feb 9, 2022 16:52:55 GMT
Some repairs to be done.
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Post by robinbanks on Feb 9, 2022 17:04:51 GMT
Looks like you have stage 3 cancer there. How will you tackle this?
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Post by duffer on Feb 9, 2022 19:59:14 GMT
Fixed a few of these now. I went for the cut it out, weld new in, then seal it. Would love to see your approach. Probably better than mine. Love this sort of work. š
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Post by dreamer on Feb 9, 2022 20:19:18 GMT
I left it with a mate to have a look at it, the Katana in my avatar was similar when I restored it was done with silver solder that was about 8 years ago and its still OK. This motor was rebuilt by the bloke that gave me the bikes this one with new pistons and rebore, I didn't like the feel of it turning over by hand so pulled the top end off this evening, you can see where the valves where just touching the pistons. Now getting fully stripped down and vapour blasted.
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Post by johnjones on Feb 10, 2022 9:01:12 GMT
Can't zoom into picture so "detail" is not visible for me.
Clearly seen are the "crescents" due to inlet valves touching the piston pockets. Not sure is exhaust valves have done the same thing.
Suspect incorrect valve timing, how was that on strip down ?
Are any valves now bent I wonder ?
Can I see a "5" or S on the left piston in the picture, not seen on right piston.
So what's caused this to happen ?
Unlikely that both cylinders inlet valves where sticky/stuck.
That leaves valve timing incorrect, head skimmed, or incorrect pistons and compression hieght/ crown protrusion at tdc ?
Check for bent valves and the possibility of broken guides.
Seen an ink stamped "3" on some piston crowns, not seen a 1 or 2.
Been hunting significance of the "3" marking, but not found answer. A factory "grading" stamp or similar ?
It's amazing the ink stamp is so clear, wish the rod grading ink stamp was as clear !!
It's always good to turn over an unknown engine by hand before a whizz over in the starter etc.. it can save you many many Ā£Ā£Ā£Ā£'s !
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Post by dreamer on Feb 10, 2022 12:07:03 GMT
The stamp on piston is actually "50" which I assume is 0.5mm oversize but I haven't measured as yet. Marks are only on inlet there is no damage done to any of the running gear, I didn't even check clearances before stripping down.
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Post by buster on Feb 10, 2022 13:47:58 GMT
looks like the cam sprocket was a tooth out?
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Post by dreamer on Feb 19, 2022 9:57:23 GMT
This engine has new rebore and pistons but the head wasn't checked.
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Post by buster on Feb 19, 2022 13:16:43 GMT
that reminds me of the cylinder head that I took off my 400a, cleaned it out with a shovel
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Post by dreamer on Jun 23, 2022 15:04:16 GMT
Off to the blasters.
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Post by buster on Jun 23, 2022 21:46:01 GMT
vapour blast? let us know who you use, all good info
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Post by dreamer on Jun 24, 2022 10:08:40 GMT
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Post by dreamer on Jul 7, 2022 20:08:46 GMT
Engine back, happy with the result.
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