External fork springs

Since the rubber fork gaiters on my Norvin have perished, I thought I might replace the existing external springs with chrome ones which could be left exposed and look much better. I bought a set from RGM but found they had 23 coils as opposed to the 20 of my existing ones also they were about 15 mm. longer. When I tried to fit them they became almost coilbound and I could not get the damper rod up far enough to attach to the top nut. Although I have used the bike with the existing (external springs) for a long time, it has always been difficult to install the forks as they have to be compressed substantially to force the damper rod up far enough to get a spanner on them to screw into the top nuts. This translates to probably about 5 cm. preload on the springs when the top nut is fully screwed onto the damper rod. I have been told recently that there should be very little or no preload as it can put undue stress on the damper mechanism. Have I been using springs which were too long? (one is 225mm long the other is 228.5mm long-another reason to replace them) or is my damper rod too short (were different lengths available?) I have owned the bike for over 40 years and its not worried me till now.

Commando forks are longer than featherbed forks, so I'd guess you've got Commando springs?

Try calling or emailing Roger at RGM as he knows the 'ins and outs' of all the differences I'm sure.

However, if you've got your forks apart, you could also try Dresda, they sell springs and seal holder kits, their seal holders take double seals too.