Yamaha’s YFZ450R has currently won a couple of ours shootouts. It handles great, gets about a monitor quickly and also is fun to ride. However, as soon as you get the maker away native the track, that is restricted by its top speed. The YFZ450R and also YFZ450X have nearly the slowest peak speeds in their corresponding classes.

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We wanted to find out if we could get some an ext mph out of this an equipment with some simple bolt-on parts. Prior to we started, we installed a finish Dubach exhaust system. If you very own a YFZ450R or any type of other sport quad, opportunities are you have actually installed one aftermarket exhaust system.

The meat that our rate search will certainly be in the type of gearing changes and also trying various rear tires sizes. We provided ITP Holeshot XC tires an installed on ITP aluminum wheels and Renthal sprockets both front and rear.


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In the chart space the top speed results of every tire/gearing combo. In the notes column, we define if the quad’s engine even had sufficient power to pull the higher gearing. Or, we listed if the share rev limiter kicked in, meaning even an ext speed was obtainable if the engine control unit was modified together well.

In the end, we provided the aftermarket sprocket choices of 15/36, since bigger 보다 stock countershaft sprockets assist gain speed, and smaller would improve solution but hurt top speed numbers. On the rear end, smaller sprockets improve speed. An additional thing you want to keep in mental when setup up your quad for higher top speeds: a smaller sized rear sprocket add to a little more ground clearance, which is, because that the many part, a great thing.

We didn’t bother experimentation the 37-tooth behind sprocket because the transforms are no dramatic as soon as only going increase or down one this at the rear. A straightforward rule of thumb is that one tooth various on the former countershaft sprocket is equal to a two-tooth adjust at the rear.


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If you have actually your slide rule handy and like a math challenge, friend can number out her theoretical peak speed there is no even beginning the quad. The formula is (R x C)/(G x 5280), where R is engine rpm in ~ redline multiplied by 60, C is the one of the behind wheels to express in feet, G is the as whole gear ratio (the primary, final and also fifth-gear ratios multiply together) and also 5280 is the variety of feet in a mile. There space two reasons we actually went into the ar to measure this through our handy GPS. An initial of all, many motors won’t traction redline in top gear. Second, tires circumference actually grows at speed, successfully gearing your quad higher as the wheels spin faster.

The bottom heat is that a number of factors affect speed. Countershaft size, behind sprocket size and also wheel dimension all come into play, as well as power. Every quad is different, however here’s what we uncovered with our Yamaha.

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RUN GEARING TIRE rate NOTES NUMBER (RATIO) SIZESTOCK 14/38 20″ 74 mph Does not hit the rev limiter, it s okay to tops rate quick.RUN # 2 14/38 22″ 75.1 mph Does no hit rev limiter, goes through 1-3 well, however 4&5 nothing pull very hard.RUN # 3 14/36 22″ 74.9 mph Does not hit rev limiter, spread in between each equipment felt much longer than stock.RUN # 4 15/36 22″ 77.1 mph Does not hit rev limiter, spread between each gear felt the longest.RUN # 5 15/38 22″ 75.4 mph Does not hit rev limiter, rear finish felt skatey.RUN # 6 15/36 20″ 74.9 mph Does not hit rev limiter, strong out of the hole and felt the finest on the track.