SUZUKI RM-Z450 OFF-ROAD PROJECT: BEHIND THE BUILD

BY MIKE WEBB

It wasn’t so long ago that 450 motocross bikes were the flavor of the month when it came to off-road weapons. All manner of Japanese bi-bores were toned down, re-valved, fit with larger fuel cells, and hosted a plethora of aftermarket goodies intended to make them off-road-worthy. But, this morphed species was doomed to extinction when the mighty KTM and its sister Husqvarna flooded the market with purpose-built off-road machines in every size. Now, it is indeed rare to spot a Japanese 450 MX bike in the sea of orange and white.

Ride Engineering triple clamps/Honda steering damper

I’ve been on Japanese 450 MXers for close to 15 years. I love to moto, and I love to ride off-road. Would it be possible to have a bike that was truly capable of both MX and Off-Road? With the majority of my friends and peers (including both of my brothers) dumping their volatile 450 track bikes in favor of smooth power, push-button starting and syrupy suspension, they snorted that my machine was meant for a younger, and possibly less intelligent, pilot. Still, I own my machine and didn’t want to have to make another payment to satisfy my greed for dual citizenship. I was determined to find out if I could make this happen. 

Plopping around at slow speeds on a 450 motocrosser can be a handful. We gave the Suzuki RMZ-450 some needed manners down low and some suspension versatility. The Rekluse CX clutch, FMF Q4 and RG3 were the main players.
Plopping around at slow speeds on a 450 motocrosser can be a handful. We gave the Suzuki RMZ-450 some needed manners down low and some suspension versatility. The Rekluse CX clutch, FMF Q4 and RG3 were the main players.

CHOOSING THE PARAMETERS
For my base model on this project, I went with a 2018 RM-Z450. As I mentioned earlier, I have the pink slip on it. I’m pretty familiar with the “Big Z” and had a solid understanding of which modifications would bring out its off-road capabilities without erasing its moto roots. My checklist included suspension that was adequate for MX and off-road, increased fuel capacity, engine performance that allowed rideability in the technical nasties but still had the needed boost for jumps, and the proper aftermarket bolt-ons to ensure reliability and performance. 

The Acerbis skid plate is durable, light, bolts on easily and offers good protection to the RM-Z’s belly.
The Acerbis skid plate is durable, light, bolts on easily and offers good protection to the RM-Z’s belly.

SOOTHING THE MIGHTY BEAST
It’s well-known that the Suzuki RM-Z450 is by no means the fastest or most powerful of the current 450 MXers. Working in its favor (for an open-class moto machine) is the softest, most rideable power of the lot. Still, the reality is it’s a kicker (no button). It likes to flame out quite easily in technical terrain. The power is full dragster and throbby compared to the purpose-built, four-stroke off-road machine, and it is way too loud. But, the machine starts easily for me, so my main ambition was to work on the low-rpm area, hoping for increased smoothness and a reduction in the dreaded coughs. 

 An IMS fuel tank adds 1 gallon, which is huge for the off-roader.
An IMS fuel tank adds 1 gallon, which is huge for the off-roader.

The RM-Z450 comes standard with three map plugs. I chose the mildest map as a starting point. Next came exhaust systems. The reality here is that the stock Suzuki header, mid-pipe and muffler are really quite good. They provide a really strong yet smooth bottom that doesn’t drop off in the higher rpm. But, taming ambient noise was a definite goal, and I also needed it to be spark-arrestor-legal. I went with FMF’s stainless MegaBomb header mated to the Q-muffler with the spark arrestor installed. This combo targets a strong bottom hit, creates a sound that’s pleasing to the ear and is legal for our off-road playgrounds. 

 FMF’s Q4 squelches some of the hard-edged decibels and is sparklega
FMF’s Q4 squelches some of the hard-edged decibels and is spark-arrestor legal.

My next mod was designed to address the low-rpm flame-out scenario. With no button to stab for immediate life, I wanted to be able to lug the machine in tight, rocky, slippery conditions and not fear the barf-stall and high-side-into-the-rocks scenario that haunt me. Constantly covering the clutch, running the idle way up and fraying nerves make the machine a handful here. My solution was the Rekluse Radius CX clutch system. This is a brilliant piece of engineering that allows normal clutch-actuated performance, but can also be used as an automatic clutch. My plan was to disarm the potential flame-out scenario and use the “ride like Palmer” technique of “a gear high and lug the heck out of the machine.” For moto and big hill-climbs, I did not want to lose the ability to control the power with the clutch, so having a viable clutch trigger was also crucial. 

It took us a few tries to get the Rekluse dialed in. Thankfully, their tech staff walked us through the setup.
It took us a few tries to get the Rekluse dialed in. Thankfully, their tech staff walked us through the setup.

Now, installing the Rekluse is definitely not for the faint-hearted. In fact, it’s downright scary. It’s a complicated system that requires patience and diligence to install correctly. Take your time and triple-read the instructions for this procedure. I spent the better part of three hours changing the oil, removing the stock clutch system and installing the Rekluse. And, it didn’t work! When I was finished, the clutch pull was stiffer than on a ’74 CZ, so I knew that something was amiss. Luckily, Rekluse has an outstanding customer service department that has the know-how and patience to walk you through your crises. After a 35-minute phone session, I thought I had it on point.

The FMF MegaBomb enhances bottom hit, but it really needs a heat shield.
The FMF MegaBomb enhances bottom hit, but it really needs a heat shield.

I finished off the clutch with fresh Maxima 530 racing oil and a sano Works Connection clutch perch assembly with a lighter, smoother pull than stock. Part of the Rekluse kit is a trick billet outer clutch cover that is superior to the stock case, and I added a Hinson billet ignition cover to provide more durability and up the cool factor.

Longer Ride Engineering pull rods help balance the chassis.
Longer Ride Engineering pull rods help balance the chassis.

With the exhaust decisions made, I turned my attention to fuel capacity. With the stock fuel tank, I can get just about 33 miles of hard-core off-road, which includes plenty of mega-sand hill-climbs. This covers one good loop in our off-road zone. I have been riding Suzuki 450s for over a decade, and in the carbureted days, I had to pack gas to barely finish a 25-miler. When we ride in other areas with longer loops, I’m forced to carry fuel, dripped into water bottles and stuffed in my vest pockets. Needless to say, I’m not real comfy being a potential human bomb. Thankfully, IMS has now developed a larger-capacity fuel tank that adds a gallon to the tank and does not destroy the ergonomics. This is a biggie. Now I can do the same mileage as the rest of my group and still retain the killer moto feel behind the bars. Installation takes patience, but the directions are solid and the result is clean.

Torc1 bolt-on grips are excellent, Acerbis shields offer a modicum of protection, and the Works Connection clutch perch eases the pull.
Torc1 bolt-on grips are excellent, Acerbis shields offer a modicum of protection, and the Works Connection clutch perch eases the pull.

Fresh Maxima radiator coolant and a high-pressure CV4 radiator cap were added. A DT1 air filter was installed to finish up the motor mods.

DUAL-PURPOSE CHASSIS MODS
As stated in the beginning of this piece, I love off-road and I love to ride moto. I still get a huge smile from killer berms, super-fun jumps and the rush of moto. But, to make moto safe, the suspension must hold up in the stroke to prevent the dreaded wallows, and I wanted this spec to be rideable on a rocky goat trail as well. Honestly, that’s asking a lot. A compromise had to be made, and here’s where RG3 entered the game. The RM-Z450 is no lightweight, but RG3 has been dialing in factory off-road and MX suspension settings for decades. It was their job to get me happy enough in the tight uglies and yet keep me safe in big rollers or on steep jump faces and landings. My spec was favoring the moto side, but I needed it to be at least “acceptable” in rocky, craggy junk. 

With the rest of the chassis hardware, I retained Ride Engineering for the triple-clamp sand linkage needs. I have been using their sano billet top and bottom clamp that uses the stock Suzuki offset and features a trick four-piece handlebar clamp. But, the kicker here is you can order it with a Honda steering stabilizer and mounting hardware. I love this Honda system; it’s not used in the same capacity as a typical damper, but is more of a gentle, calming influence on the semi-nervous Suzuki steering and actually helps keep the front wheel more planted. Out back, the Ride Engineering pull-rods were installed. They’re a touch longer than stock, and this gets the chassis balanced and allows the use of a reasonable sag measurement, so the machine feels less tense and is more comfortable.
   An oversized floating Braking front rotor was installed to help slow the big girl down.

FOCUSED BOLT-ON TRICKERY
With the guts of our project complete, I turned my attention to purpose-driven, bolt-on mods. There are a lot of ways to spend your money on needless aftermarket bling. My goal was to have every aftermarket item serve a purpose.
     For plastic, I chose Acerbis. The fit was spot-on, and I was stoked with the new skid plate. This plastic piece was a cinch to mount, and now offers ample protection for the vulnerable underside, plus just a tad for the clutch and ignition covers. TM Designs came through with its super-strong and proven chainguide and engine case saver. Sunstar supplied an O-ring chain and stainless steel rear sprocket. I pretty much use stock (50-tooth) rear gearing but swap to a 51 when taking on tighter terrain. Ride Engineering provided the really impressive titanium Raptor footpegs. They’re wide, super light and flat boss. Torc1 was my choice for handlebar grips. Torc1’s bolt-on grip has great feel and took seconds to install. Seat Concepts provided the Super Gripper seat cover. Decal Works came up with the graphics package that fits like its OEM, and finally Dunlop MX33s front and rear were mounted with Dunlop heavy-duty tubes. I stuck with the 19-inch rear, mainly because I’m used to it and the budget was pretty much used up, so new wheels were not part of my plan. 

There’s honestly no way to make the RM-Z450 totally civil for off-road. Giving it some suspension cush and the Rekluse CX clutch, which has an auto/and manual engagement, gets rid of the majority of the slow-speed flame-outs.
There’s honestly no way to make the RM-Z450 totally civil for off-road. Giving it some suspension cush and the Rekluse CX clutch, which has an auto/and manual engagement, gets rid of the majority of the slow-speed flame-outs.

REAL WORLD TESTING
After shooting the beauty shots in the studio, we finally got the project Z in its off-road environment for the shakedown. To be honest, the day started off quite miserably, as the Rekluse clutch wasn’t engaging. Despite being way out on the moon, I called Rekluse and was instructed to dismantle the clutch and make an adjustment that took up the slack in the clutch pack. Then, I hit the trail. 

Here’s a breakdown of the hits and misses:

—The Rekluse clutch performed wonderfully, though to be honest it took some time to get used to. For a guy who has decades of clutch feeding ingrained in his DNA, just letting loose and hanging on requires a different skill set. I found that I would miss key turning points because I wasn’t purposely attacking the terrain. That’s the beauty of the Radius CX; you can use the clutch just like a stocker, and then feed the clutch to control the machine’s power (there is no change required). But its real charm comes in the feet-out-plonk-and-bounce in a rocky stream bed, or a tight, slippery, first-gear off-camber where you stay a gear high and hang on just to get through and over the obstacle. Forget the clutch lever. Click it up a gear and roll it. It’s a game-changer in the ugly stuff. 

—The FMF MegaBomb and Q provided similar power to stock yet at a lower decibel level. We felt a slight loss of upper power and maybe a bit more hit down low. It’s a good combo, though we did have an itch with the ’Bomb, since it burned holes in our pants and really needs a heat shield.

—Love the IMS tank. It feels as slim as stock, did not hinder the ergos of the machine and totes a full gallon more petrol—wicked good. Dunlop rubber—superb. Gripper Seat Concepts cover—almost too good. It will pull certain pants right off your derrière. Looks—top marks to Acerbis and Decal Works. Sunstar drive line and TM Designworks guide—all brutally effective. And kudos to Ride Engineering for enhancing the stability and chassis feel with its clamps, stabilizer and pull rods. 

—Other bits: I modified an RMX headlight to give it an off-road feel. Acerbis handguards fend off minor slaps. Torq1 grips give excellent feel and ease of installation. RG3’s suspension still feels brutally stiff if you compare it to a WP Xplor fork, but then again, slamming into a third-gear, hard jump face, it would feel like it had fountain-pen springs trying to hold it up. I may have them valve the fork a little softer in the mid-stroke for additional compliance, but the balance is good, and it can take on two sides of the sport quite nicely.  

In the end, my kicker RM-Z450 is more versatile in the two arenas I play in—moto and off-road. It’s still a handling dream in my moto forays, with virtually no downside with the new modifications. Off-road-wise, I’m way better off. It craves the high desert. I can get in some serious loops without fear of running dry on petrol, and when the going gets nasty, it’ll plonk quite adeptly in tricky terrain with a far bigger appetite.

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