SOHC.co.uk Forums > CB350/400
Barrels on but pistons won't move, what's going on. Help me !!!
billdn:
--- Quote from: Oddjob on May 21, 2022, 10:37:12 PM ---Are you sure the rings were fitted the right way up? They are normally marked with a T which goes uppermost.
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Oh yes made sure of that resorting to jewellers eyeglass to check profile of rings. Oddly not marked with a T but an R on top surface.â¹
billdn:
--- Quote from: Nurse Julie on May 21, 2022, 06:44:39 PM ---https://youtu.be/ViEjQ7B1uM8
The above will give you a good understanding of what you are measuring with the end gap and how to do it Bill.
You don't measure piston/ bore clearance with a feeler gauge, you need a bore gauge to determine the bore measurement accurately. The difference between the skirt measurement of the piston and the bore is the piston / bore clearance. This should be about 1 thou inch maximum clearance. Unless you have measuring equipment with lots of decimal points, you won't get an accurate reading. I'll just have a look in the manual to see what the ring end gap should be as I can't remember.
Edit.... It was easier for me to take a photo.
(Attachment Link)
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Useful clip Julie, explained it well. The photo from manual I gave a photocopy of to engineer shop. Hopefully he read it 🙏 😬
billdn:
--- Quote from: Bryanj on May 22, 2022, 07:02:05 AM ---Another possibility is a scraper side rail has twisted, been there
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Could well be as it was roughly around that point that things started to get difficult when fitting barrels. But all 4 ,although they are very fine and came in 3 parts. Something else to rule out.
Cheers Bryan
Bryanj:
The R is a different make, all ltters/numbers face upwards
billdn:
No. 3 piston out as oil scraper ring bent, 🤨 good shout Bryan ,sadly. Also left score in barrel, back to engineering shop tomorrow to see if salvageable 🤞.
Ring end gaps on first and second ring no greater than 0.25 ,as 0.20 went through but 0.20 +0.05 wouldn't, oil scraper gap no more than 0.40.
BTW piston without rings on slid perfectly through all bores.
Stay tuned !
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