SOHC.co.uk Forums > CB500/550

running on unleaded !!

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florence:
I had exactly this on a 550 years ago.  My friend bought a bike that had been standing for a year or so.  Unfortunatley, the seller had taken the bike for a blast to make sure all working OK.  My friend bought the bike but soon complained that it wasn't running properly and was smoking.  When I investigated I discovered that there were broken rings on all four cylinders.  Luckily, they had stayed in place and not scored the bore and a new set was all that was needed.

Johnwebley:

--- Quote from: Bryanj on July 16, 2013, 07:40:33 AM ---Thats not detanation as the cause, what happens is some idiot PO reved the nuts off it when cold and the rings expand to quickly so the top one shatters into pieces, this widens the ring groove then flame passage and heat finish it off.

Used to happen quite a bit on 250K4 and CB175's

--- End quote ---

--- Quote from: florence on July 17, 2013, 10:31:20 AM ---I had exactly this on a 550 years ago.  My friend bought a bike that had been standing for a year or so.  Unfortunatley, the seller had taken the bike for a blast to make sure all working OK.  My friend bought the bike but soon complained that it wasn't running properly and was smoking.  When I investigated I discovered that there were broken rings on all four cylinders.  Luckily, they had stayed in place and not scored the bore and a new set was all that was needed.

--- End quote ---


 thanks for the hints !!

I can't remember racing it when cold,

BUT,from now on will keep it below about 5k for a couple of miles at least,

thanks

John

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