People always want to improve performance on their bikes. It’s simply in our nature as motorcyclists. And so we should, there’s nothing like personalising your own bike. Most commonly, people will look straight at the engine and think, ‘how can I get more power and make this thing go faster?’ Realistically, the motor is probably the last place you should be looking.
A 520 conversion kit for is an easy way to save unsprung weight and gain performance. It may sound ridiculous, but by simply changing your regular 525/530 chain and sprockets to a 520, you’ll gain roughly 1.5hp on the dyno and save nearly a kilogram. While that may sound like bugger all (and some people won’t even notice a difference TBH), it’s practically free performance and I found it to be noticeable.
As you are reducing unsprung weight, the gains have a greater effect than dropping the equivalent in sprung weight (unsprung weight is pretty much anything that isn’t held up by the springs/suspension). Your bike has less rotating mass to deal with. I have seen several articles where shops have conducted back to back dynos with the exact same bike and gained 1.5hp by simply changing the changing to a 520 kit (using the same gearing too).
People will bring up the fact that 520 chains will wear out faster than 525/530 chains. Ultimately, if you start to nitpick, yes, they will. The tensile strength of the very top chains will be slightly higher (my EK520 chains’ rating is 9400 where the top DID 530 is roughly 10400). Bear this in mind though, a stock OEM chain tensile strength is lucky to be 6500. By putting on a high quality 520 chain you will still be gaining a significant amount of tensile strength and chain life as many OEM chains are shite.
In my experience, I did not notice any difference in wear going from a 525 to a 520 on my ZX10R. And you can’t say I didn’t ride that thing. I did several track days, road to Phillip Island and back (a 4700km round trip) and commuted daily. The bike also had less drive train ‘snatch’.
The price of a 520 chain is generally less. I was able to purchase a top of the range EK520 chain for $140 where I was quoted $240 for a 525. The same can be said for sprockets.
By nature of their smaller pitch size, sprockets are generally lighter. Frequently you will find that 520 sprockets are also designed to further save weight. If you are using the bike on the street, be wary of aluminium sprockets though as they will wear much faster than steel.
So, who should consider making the switch to a 520 kit? I think anyone with a bike under 1200cc can realistically look at making the change. If you are running a 600-1000cc sports/naked bike, go for it. You are saving unsprung weight, gaining performance and improving chain and sprocket life over a cheap OEM set-up. If I was running a big bore or a touring machine, I would stick with a larger pitch. In the end, a larger chain of the same quality will last longer.
Another thing to consider is, do you actually care about that little bit more performance? Some people honestly couldn’t give two shits and that’s fine. I also wouldn’t make the change unless you are due for a new set of chain and sprockets. Why? Unless you are that person is chasing that extra little bit of performance or running a track bike, the gains aren’t worth throwing away your current set (and money). But, when it’s time to freshen up your drive train, definitely consider changing to a 520 kit.