Author Topic: What to look out for when buying a Dragonfly  (Read 3752 times)

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Offline gsx1100s

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What to look out for when buying a Dragonfly
« on: 29 Jun 2006 at 07:43 »
I found this interesting article ( although from 1989 ) I hope some of the information might be helpful to  Dragonfly owners,
cheers Michael


It starts with............

Be wary of any machine missing larger cycle parts or any electrical components .Rear mudguards are now available in  glass fibre and a BSA B31 – type dual seat will fit a Dragonfly , but Miller electrical parts are very scarce .
This includes the rear light . There is commonly wear on the lobes of the two gear driven camshafts , with consequent damage to the flat based cam followers. Cams can be re-profiled  sub standard parts makes hardening a problem).
Carburettor wear is common and may be exacerbated by poor sealing on the inlet tract pipes. The neoprene O-rings at each end of the chromed tubes harden with age and must be replaced.
Wear on the distributor shaft bush will result in variable timing and poor running .This can be replaced. Check the timing by starting the machine on emergency ignition. If it will fire up readily , but then fluffs into an uneven beat when the throttle is tweaked , then the timing is spot on.
Oil leaks are usually the result of the crankcase being over pressurized. Look out for a dribble from the wiring grommet in the timing chest. This is perfectly normal , the cure comprising a new grommet and lots of silicone sealant behind it. But the pressure release valve – a spring-steel flap valve – may be stuck due to internal condensation and corrosion. New units are available.
Gear boxes can leak down the gear change shaft where a steel bush wears the shaft. An external felt sealing washer is standard , but machining the bearing to accept an O-ring is a permanent solution. Likewise , a sealed output shaft bearing will keep the gearbox oil where it belongs.
A little oil may get past the distributor shaft seal and drip down . most owners simply position a piece of sponge rubber to catch the drips as this cannot be seen under the metal cover above the crankcase. If oil gets past  a worn crankshaft oil seal at the rear and into the clutch housing it will, despite the presence of a drain , eventually cause the unit to slip. The cure is to fit a new garter seal. At the front of the crankshaft the condition of the top-hat bush is vital in maintaining oil pressure. If an engine has been overhauled this bush should be replaced as a matter of course .
Rapid wear on the phosphor-bronze front wheel spindle bush afflicts machines fitted with British Hub brakes . this allows the back-plate to flap around and is easy to spot.
Its also important to realize that the Girling units fitted to the Reynolds –Earles front fork are  longer than those on the rear of the machine . fitting any old units will have a bad effect on handling. Leaking units can be rebuilt. The correct tyre mix for a Dragonfly is a rib front and a block pattern rear .Tyre pressures are critical if good handling is to be maintained.
There does seem to have been some variation in front end geometry on Dragonfly chasis from new. This can be measured by slipping your hand , sideways on, between the cross tube of the front fork and the generator cover . Sometimes , only two fingers will fit into this space , but it may accommodate as many as four! If the latter is the case , asses steering and handling peculiarities during a test ride with extra care.This is no myth , for I have checked five dragonfly models for variations here and found that they were precisely as predicted . it’s relatively easy to convert a dragonfly to 12 volt electrics . Machines have also been fitted with electronic ignition using a Boyer Bransden kit.

« Last Edit: 30 Jun 2006 at 06:27 by gsx1100s »
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