Dragonfly of dispair Smoking barrel

[AndyMorgan]

Any advice please
My rebuilt Dragonfly engine is very smoky on the left hand pot and I get an oily plug running for 10-15 minutes the smoke doesn't clear, much more and the shed becomes a health hazard.
It has been rebored to 63mm with oversize honda 250N pistons on both bores to clean off a significant amount of corrosion, this engine was a basket case, Both ring gaps are good at 0.01" and only the left hand is smoky. New gaskets and  the head doesn't seem warped or cracked.
Any clues, things to try or experience of treating similar cases.

Cheers

Andy

[oily bloke]

Its possible that one of the rings is upside down or oil is getting past the guides. Probably the former.

[eddie]

Andy,
           Do you know what pistons are fitted to your engine? Are they genuine Honda or pattern pistons? I have used both types in the past, and genuine pistons are much better quality. Also, carefully check the ring widths - some pattern rings are of a slightly different width, so could be pumping oil.

  Regards, Eddie.

[AndyMorgan]

Thanks,
I got Hepolite pistons so guessing they're not genuine Honda parts.
I will swap the pistons over and see what happens but pretty sure the rings are right and the right way up, will do a side by side comparison to check.

Cheers

Andy

[AndyMorgan]

On side by comparison the smoky barrel piston top ring appears much more rounded slightly shiny just in the middle compared to the others non smoky barrel flat surface. Seems I have an odd ring. So good to get to the bottom of a problem, now where to get AE piston rings for 62.5 (I made a mistake earlier as the rebore was to 62.5 not 63.0)

Photos
1) smoky barrel top ring profile (rounded)
2) non smoky barrel top ring profile (flat / beveled edge)
3) both rings top surface AE ring non smoky, N50 ring smoky.








[Attachments converted to linked images. 25Nov21 -Doug, Admin]

[dalgrae]

Hi try Cox and Turner in Somerset

Regards. Colin

[Vermont-Ian]

Another possibility - oil gets in via worn valve guides or valve stems.  (From personal experience).

[oily bloke]

Personally I would have bought genuine Honda if I could find them. Start with Dave Silver Spares.
Good luck

[AndyMorgan]

Problem appears to be solved. Many thanks

Andy

[Jonathan Hewitt]

Good morning, so what did solve the problem ?
  Jonathan

[otaio26]

Agreed,I would like to know your solution to the problem,as I had similar problem.

[AndyMorgan]

New rings