alot of that has to do with how good your bearings are and the alignment on the carrier if its eve nslightly crooked it will really rob power and be hard to push ,for the money the RK chains are really nice and made in japan and cost half of a renthal with high tensil strength rjatv.com sells these for reallygood prices
I agree 100% bearings mean allot, I have seen some bearings that though smooth they were real tight and caused too much drag. Also if the brakes aren't adjusted properly the pads will drag on the disc.
RK is a good chain no doubt. I have one on my stock blaster. It's a good quality light weight chain. One thing to watch out for with the RK chains is there is RK and there is RK-M stay away from the RK-M because even tho they are the same exact parts, the M is assembled in Malaysia
RK Japan = good
RK-M Malaysia = ok
One other thing to be aware of when buying chains is some of them are dual shot peened and some are quad shot peened. That means how the end of each pin is hammered to lock it into place. The dual peened kind are good but the quad peened is the best for ATV and heavy duty use.
Something else I like to do is at least once a year, I like to remove the chain and soak it in kerosene over night, and then I use a small soft wire brush to clean the whole chain one link at a time then I oil it up real good with some light oil and put it back on the quad with a NEW master link, ride it for a couple minutes then go over it real good with the chain oil. It's a good idea to inspect your sprocket teeth often aswell.
Trust me you don't want your chain to bust or come apart on the quad because it will damage your case at the very least. Lately when I go to look at a quad to buy, they have all had the cases cracked in front of the sprocket from the chain smashing it. Some try to fix it with JB weld and if your lucky you can get away with that, but the only real fix is a new case.
Most professionals will tell you to spend $100 on a chain but really if you are going to take care of it you can get away with a $25 RK chain and live worry free.