The 8DN weights are too light, the Dalton is an excellent choice, they have the adjustable ones now that you can tune on the hill quicker. You need the the weight of the ramps to close the primary so you can shift out the secondary. If your secondary spring is too stiff, the primary can't close up and then it slips, you can see this on your photo's, the black mark near the top of your shift out on the primary matches the black mark in the middle of your secondary. Once the clutching gets there, the weights stall out against the stiff secondary spring and then the motor is left to try and get more by slipping instead of shifting, then it builds heat and deteriorates the belt. There is a book by Olav AAen called "Clutching Made Simple" an excellent book to understand what is happening. Next to the drive chain, your clutching is the most important detail for getting power to the ground, because all the power in the world won't mend a broken chain or and blown belt.
Get some Dalton adjustable weights, about 60- 66 grams, use the primary springs you have, they are a good start, get a Cat Yellow secondary, you already have the 14.5 rollers, take your extra helixes and secondary springs too, keep your 19 tooth ( one thing at a time ). Clean your clutch surfaces with scotch brite, do not use brake clean or any other cleaners, the chemicals in the cleaners can destroy the bushings on the sliding sheaves, use warm water with a mild soap if you need to. Find a consistent hill that is a 30- 40 degree slope on some fresh snow, not too deep, that you can move across with each run and change one thing at a time, take a magic marker with you and put a thick line on the face of the sheave, mark it with a number 1, go for a run up the hill carefully watching your track speed and RPM, return to bottom and mark it down in a note book, check your belt heat as well, if you're too low in rpm, typically you would lower the ramp weight, however keep in mind that if your RPM goes up and the speed goes down, it's slipping. Put a black stripe on your primary again, mark it with a 2 and do a run again, if there is less or more of the black mark showing this will tell you which direction to go your clutching, keeping in mind to watch your track speed and your RPM, this is your "Dyno". I've spent a whole afternoon, just dialling in the clutching sometimes.
There is some great advise on here, but not all clutching works the same, different weather, snow, rider weight and riding style all play a factor into setting up your clutching, so getting your clutching to work for "you" is something really only "you" can nail down perfect, but you need the tools and understanding first, just remember to change "ONLY ONE THING AT A TIME" and get Olav's book. The Yamaha belts are the best out there, but even they can only stand so much heat.
I hope this helps.
Linc
