I'm planning to make up a couple of stainless steel extension arms for the mirrors and wonder if someone knows the exact thread size of the lug that they screw into on the bar fitting.The locknuts take a 15mm spanner so the thread would probably be somwhere between 9mm and 12mm.
I'm lead to believe that there's a slight difference in the thread profile between European and Japanese metric threads for sizes over 12mm sizes so hopefully someone would now what i'm rattling on about.
The new extension would also raise the mirror height as well as bringing them further out as at the moment i'm getting a perfect view of my jacket sleeves at the moment.If anyone else has made these perhaps some dimensions or measurements would be possible.

I have read that the threads are 10mm. Is this the measurement you need? I hear the Reflex and the Burgman 400 mirrors work on the SWing and they also have the 10mm thread. Take some pics on how you do this and post them if you have time. I'm sure we would all like to see them.

10mm. I put Burgman mirrors on mine they work outstandingly well. Click the picture for larger view.

DickO
This is "Old Dave" again!
I made two extenders for my 05 SWing. Took a piece of 3/8 in aluminum and cut them out of it with my old saw. I could have use metal as I'm going to paint them black. You do need two 10mm bolts and those are kind of hard to come by here where I live so had to order them. They are the automotive fine thread. You will see when you remove your mirror.

Dave Read

I live in Kent and researched mirror extenders for 2009 Silverwing as also fed up looking at my elbows.

I purchased the following Honda parts and they extend mirrors sufficient to give unobstructed view behin - they also do not impeed on Givi windscreen on full lock

Part No 88111mct000 - you need two and these are extender bars - £37.32 the pair
Part No 90314mb6000 - you need two and these are lock nuts - £3.80 the pair

Items ordered and supplied by Kent Motorcycles, Honda dealer

Hope this helps

Bill

FOTGOT TO SAY - Original mirrors just screw into new fittings and job done

Bill

Thanks everyone for your responses - all very helpful.I guessed they were probably 10mm threads but my ex-Moto Guzzi 10mm allen socket bolts would start a couple of turns then pinch up.The thread profile is different even they are both 10mm.
I like the Burgman mirrors as they look to have much larger heads although I'm really looking at the least expensive option and think I'll have ago at making a pair of extension arms

Just had my best ride out yesterday since getting the bike in March.Geograhically speaking it probably won't mean much to our friends across the pond when I say I started out at 7.45am from Bromley, Kent and went to Leighton Buzzard (Narrow gauge Railway),across to the Glos.& Warwick Railway and home for supper at 7.30.Super A & B roads,mostly empty,dry weather,excellent machine and 58mpg over 270miles.That might not seem to be a big mileage for a day if you're USA based but in the UK its a different scenario.To give you an idea - Googlemap the route I took starting with the A41 from London - Leighton Buzzard-Winslow-Bicester-Moreton-Stow-Toddington-Cheltenham-Swindon-Bracknell-Guildford,West Wickham.
Cheers and happy riding!