Thought this may be of use. Have found the goods and service from Electrex to be very good.
No commercial/family/friends link to the outfit.
http://www.electrexworld.co.uk/acatalog/STK-502.html
All the best
Steve
yes vast differance i fitted one to the spada - as it was not getting used a lot i found every 3 weeks the battery would loose its edge and needed charging (was not reving it enough)
fitted one of these and never charged again as the actual power comes in a lot earlier (2000revs)