Douglas - For Sale Items

Douglas 1913 Model P motorcycle

Douglas - Wanted Items

Douglas 1915 3 Spd-Gearbox and Clutch

Support & How to Join

Side Panel Notices

Quick Comments

Reminders, links to interesting topics, bump your own topic, quick comments or any short message of interest to members. Try it out!
Please note - 500 character current limit


Dave

Today at 01:04:34
Welcome to the new site!

Recommended viewing for a fast start...
 - Quick Tour of the Front Page
 - Quick Tour of the new Attachments

Please see the bottom post in this topic for more info.

will Dragonfly pistons fit Mk engines

Started by Ray Dodds, 23 Oct 2012 at 07:16

Previous topic - Next topic

0 Members and 1 Guest are viewing this topic.

Ray Dodds

Will Dragonfly pistons fit Mk series engines or is there an alternative piston available ,ie japanese

eddie

Ray,
        Dragonfly pistons will physically fit in the Mark series engines, but I wouldn't reccommend it. The Dragonfly pistons are of the split skirt type and are prone to collapsing if worked hard. The favourite mod is to go the other way and fit Mark pistons in the Dragonfly. A more common mod on the 'Fly is to use Honda CB250N pistons - these are 62mm dia, so work out at +48 thou on standard size. The Honda piston has an odd crown shape but works well. The only other modification needed is to replace the small end bushes with ones with a 15mm bore.
  Hope this helps,
               Regards,
                            Eddie.

Ray Dodds