Suzuki RMX450Z

Suzuki instead went the four-stroke route with the DR-Z 250 and 400. Both were solid trail bikes, but were too heavy and old fashioned to be competitive without spending a fortune on modifications. Serious off-road customers ignored them and continued modifying RM 125s and 250s for off-road racing. The release of the all-new RMX450 raised a ton of questions. Would it be a fat trail bike like a DRZ400? Would it be a ‘soft’ motocross bike, more suited to GNCC racing than fun weekend trail rides? Despite high demand for the new machine Suzuki dragged its feet getting the RMX to dealerships. We were glad to finally receive our test bike and answer those questions once and for all!

The RMX is indeed pretty much an RM-Z450. The fuel injected 450 engine is based on the motocross version, albeit with milder cams, some EPA mandated intake and exhaust neutering, and the prerequisite electric starter. The transmission ratios are wider than the RM-Z, but still reasonable for singletrack and moto use. The frame is based on the 2009 RM-Z frame, which Suzuki factory test riders preferred over the 2010 RM-Z frame for its flex characteristics.

The suspension components are the same as the RM-Z, just with more off-road appropriate valving and spring rates. Compared to the typical Japanese ‘enduro’ bike the RMX is a very serious offering. Going by specs alone you can tell Suzuki was targeting serious weekend trail riders who like to mix up their woods rides with some motocross and cross-country seat time. Sounds good so far!

Everything on the bike is tucked in well – it has a skid plate, radiator overflow tank, a back up kickstarter, a quick access airbox, minimal lighting and a kickstand. It’s even got a digital trip meter with a low fuel light. The bike shares the same small alloy fuel tank as the RM-Z. The Internet is full of people crying about the bike’s short range. That depends on how you use the bike. On the East Coast, and with the proliferation of ‘new school’ enduros with gas stops closely spaced together, the gas tank size might be a non-issue. We loved the slim ergos and think they are well worth the trade-off in trail riding range…sort of. We got around 30 miles to a tank of fuel, riding hard. Thankfully the aftermarket is working on bigger tanks for the cross-country and trail-riding crowd.

Anyway, all the enduro gear added a lot of weight to the RMX. It’s about the same weight as other bloated enduro four-strokes, 272.3 pounds. That’s about 25 pounds heavier than the RM-Z motocrosser. Some of that weight can be carved off quite easily for racing, and the battery and electric starter can be even removed without affecting the operation of the engine or fuel injection system. The RMX kick starts pretty easily too, so maybe that isn’t as silly an idea as it sounds.

What’s it like to ride? Our shorter test riders loved the general feel of the RMX. It also turns well, with the tradeoff being questionable high-speed stability. That’s a Suzuki trait that drives some riders crazy, but it’s one that we can live with. The fork is awesome, generating zero complaints. The shock was a little confused, feeling like it needed stiffer overall valving. Our 160-pound intermediate ended up stiffening the rebound and compression to get the back end to quit wallowing.

Like most EFI dirt bikes dead engine electric starts take a few revolutions. We found it much faster off the line just to kick start it. In choked-off EPA form the bike is also slow. It won’t wheelie in third without using the clutch, it won’t rev out, it flames out and runs really hot. With the EPA stuff in place the flywheel feels too light and the bike feels like it’s geared too tall. It drove us nuts! Our bike didn’t have the half-throttle stop the U.S bikes use to meet EPA specs, but it did have the pencil sized exhaust tip and sealed up airbox. We brought it home, read reports online saying the bike won’t run right without that EPA stuff, and then we took it off anyway.

Results? Instant transformation! The bike did unfortunately become about as loud as the motocross version, which isn’t exactly obnoxious but is still too loud to be politically correct. Despite what we’d read our bike didn’t run noticeably lean in our humid 85-degree weather with the exhaust and intake unplugged. There are aftermarket gizmos to add to the wiring harness which richen the EFI settings if you find the need. We didn’t.

The uncorked, ‘closed course only’ RMX now ran like a real 450 should. A torquey, powerful and very smooth 450! The gearing and flywheel weight suddenly felt just right, throttle response was crisp and power wheelies in any gear were possible. It never stalled or boiled after we uncorked it, and we actually preferred the smooth power delivery of the milder RMX to that of the motocross version.

We didn’t have time to unbolt the other stuff that weighed it down, but the potential of the RMX to become a winning off-road race bike is very real. You can feel the weight of the highly placed battery, but the bike is light on its feet for a 270-pound enduro machine.

Stuff we didn’t like? The airbox is quick to access but it is very difficult to get the filter element itself in and out. We took off the seat and peeked in with a flashlight just to be confident the filter was seated properly. The bike is too slow when corked up and too loud when it’s uncorked. We’d love to try it with an Akrapovic or FMF-Q silencer, guessing it would be a great compromise.

So what do we think? When uncorked the RMX jumped up to the position of our favorite 450 of the year, solely for its ability to do just about anything well. It turns great, it’s fun to play on and will run pretty hard on a MX track without being too unruly for the forest. But if we were casual trail riders used to typically fluffy Japanese trail bikes, or long distance adventure trail riders, the RMX wouldn’t rate so highly. This is an all-around fun, competent motorcycle with a ton of untapped potential.