Piston identification

[Sgtbiro]

Hi
I have just found two pistons in a old box of Dragonfly parts that am going through,they are stamped on the top with the number (20647)
but in my parts book it says that the part number for Dragonfly pistons is (34193) can anyone tell me if these are the correct pistons, i also found what looks like a brand new piston but has no number stamped on it is just stamped STD on the top.

Cheers Kevin..

[eddie]

Kevin,
          As you say, Dragonfly pistons (bare) have the part number 34193. Mark 3 - 5 pistons are numbered 37537. T35 Mk1 pistons 33085. Pistons with just the size stamped on the top are probably from the batches of repro pistons the LDMCC have had made over the years. If you post photos of the pistons you have, I will attempt to identify them more precisely.

Regards,
             Eddie.

[OCTypeCanada]

Maybe like this one: http://www.vintage-motorcycle.com/index.php?language=en&site=4&pid=315&id=18347&suchtext=20647&limit=0

[Sgtbiro]

Yer just the same as the one in the link.

Cheers kevin.

[eddie]

That piston is probably for a Douglas generator engine (scarf joint piston rings) but is incorrectly listed as being 60.1mm - it should be 60.8mm.

  Eddie.

[Sgtbiro]

Cheers Eddie so no good for my dragonfly then.

[eddie]

No, I'm afraid not! The generator engine and T35 Mk1 had different shaped cylinder heads to the later models - hence the higher crown on the early pistons.

  Eddie.