I spent some more time on the dyno this weekend testing exhausts and fuel controllers for a big writeup I’m working on. In the process, I also had a chance to personally test my 415 chain and sprocket kit against the stock 520 chain and sprockets (well, actually the rear sprocket was a lighter Vortex sprocket, but the chain and front sprocket were stock). The results are impressive, and undeniable. The stock 520 chain is a thick, heavy, o-ring style chain designed to last probably 30,000 miles or more on the R3. However, this heavy chain adds a lot of unnecessary weight and resistance to the drive train and robs horsepower before it ever reaches the ground. Changing to a 415 non o-ring chain and sprockets removes about 2.5 lbs from the system, and removes tons of friction, increasing the amount of horsepower and torque that actually reaches the ground at the rear wheel.
These runs are done with a standard procedure, 4-5 runs each until a peak number is reached, then it drops again. The highest number is the one recorded for both. And these runs were done in the middle of the day, after lots of other testing so the bike and dyno are already hot. The 415 runs were done first as part of some other tests, then I rolled the bike off the dyno, changed the chain and sprockets as fast as I could (about 30 minutes), then rolled the bike back onto the dyno and did the 520 runs. Nothing else changed, same bike, tune, dyno, settings, everything the same to be fair. The actual time between the compared runs is about an hour and 10 minutes as shown in the time stamp under the chart.
Also note that the 520 runs were done with a 14T front sprocket and 44T rear sprocket (a ratio of .318) while the 415 runs were done with an 18T front sprocket and 56T rear sprocket (a ratio of .321). So technically, the 520 kit had the gear ratio advantage and should have revved slightly faster. However, you can clearly see (and I’ve marked it if you can’t), the 415 kit not only produced noticeably more power (+.62 hp) and torque (+.29 ft lbs), it also revs faster and reaches peak HP and torque sooner. Look at the gap between points on the run, and notice that as both runs progress, the gap gets larger and larger between the same points, displaying that the 415 run is revving through the RPMs faster, even though it had a taller gear ratio.
This is why changing from a 520 chain and sprockets to our 415 chain and sprockets is arguably the best performance improvement per dollar you can make to the Yamaha R3 and is a must have for all racers. The trade off with a running a 415 kit instead of the stock 520, is that the chain is smaller, lighter, and weaker, and will have to be replaced sooner than a 520 chain. If you are willing to monitor your chain slack to be sure to change your chain before it fails, you can gain a significant advantage with this modification.