Ok so how did the Malossi Derbi Senda 50 Reinforced Clutch Spring do?
After my 136 mile jolly to the Welsh border the spring looked and felt much the same as before. The belt was held in what seemed to be adequate tension to wrap itself around all three pulleys and the FS tensioner could be compressed down then released so that it returned to its previous position. When pushing my XB around it nearly felt like ‘no belt was attached’, like the blue spring, but not quite as taught as the red spring l had tried before.
Typically l forgot to actually measure the Malossi spring length before my Sunday run.
And when you come to measure something, it’s never quite what you expect! After my ride out the 32mm spring has been compressed by the adjustment nut to a mere 18.27mm, or 10.5mm approx of the way alongside the adjuster thread. When l pull the belt upwards the spring can compress to a mere 16.78mm.
So the actual maximum spring compression movement as set is only 1.5mm.
But the actual belt at mid point was displaced upwards by 14mm in the above exercise due to the effective length of the FS lever arm. The eye can deceive as the spring seems to be moving far more than only 1.5mm. Whatever, it seems to work.
Most FS equipped XB owners would swear that my belt is far too slack, but is it? I felt no ill effects on Sunday. Although being a tiny bit too lose around the pulley teeth where maximum load is applied may result in increased wear? I will have to read up on this. Although on my last ride in cooler late summer air at 1020mb, the effect of my exhaust Venturi when winding the throttle on at 3800rpm felt like a supercharger, and things can go a bit ballistic for the next 1500 rpm. At one point the front end went very light, next the rear broke traction crossing a line on overtake, and it seemed to go from 50 to 90 more like an XB11 than a 9!
Or maybe l just get excited more easily in my advancing years.
I doubt if it would drive so well if the belt was dangerously slack!
Next stop the double spring experiment!