| I ran Sigma slipper clutch in 2006 and can recommend it - I will be running a Sigma clutck in my Thunderbike next year.
Mine was a 5 speed 620SS. The standard clutch has a tendency to grab when coming off the line and I know others have had problems with clutch slip (mine was OK with an extra steel plate in the pack).
The Sigma slipper clutch cured all those problems; it gave smooth take up coming off the line; never slipped (once we'd got the correct spring combinations sorted) and made the bike much more stable on the brakes into the turns - I was a sceptic but ended a convert! | 
16-Dec-2006, 08:55 
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