Project Bike: Cylinder Works/FMF/Rocky Mountain Suzuki RM-Z270

Jay Clark Enterprises gives the 2016 Suzuki RM-Z250 a displacement bump for a little more thump.

Scott Rousseau

Jay Clark Enterprises gives a 2016 Suzuki RM-Z250 a displacement bump for a little more thump.

With the help of a Cylinder Works Big Bore kit, Jay Clark Enterprises gave a stock RM-Z250 a little extra grunt. Now displacing 269cc, the RM-Z can rocket out of a corner with authority.
With the help of a Cylinder Works Big Bore kit, Jay Clark Enterprises gave a stock RM-Z250 a little extra grunt. Now displacing 269cc, the RM-Z can rocket out of a corner with authority.

Suzuki engineers made a laundry list of updates to the 2016 RM-Z250, and yet as good as the overall package is, the RM-Z’s engine performance is simply not on par with the top dogs in the 250cc class.

Sure, its 249cc, liquid-cooled, DOHC, four-valve, semi-dry-sump engine has its fine points. It offers linear power delivery with minimal vibration, and it produces decent low-end torque mid-range power, but it lacks the punch of its competition because its power tapers off too much up top. The Suzuki isn’t slow, but it sure isn’t fast either, and that forces the rider to keep the throttle pinned and pay attention to momentum conservation in order to negotiate obstacles that other 250s can clear with merely a strong blip of the throttle. And that’s frustrating because the RM-Z250 is blessed with an aluminum perimeter chassis that serves up classic Suzuki handling, and its suspension may be among the best in the class.

Boy, if only there was a way to give the RM-Z250 more thump to better utilize that sweet chassis and awesome suspension. Well, there is, as Jay Clark Enterprises showed us with their Cylinder Works/FMF/Rocky Mountain ATV-MC Suzuki RM-Z270 project bike.

Now, right off the bat, we know what you’re probably thinking: Since the Cylinder Works kit bumps the RM-Z’s displacement to 269cc, it is illegal for 250cc class competition. True enough. However, as Clark explains, adding displacement is the easiest way to make the gains that he was seeking for the RM-Z while keeping all modifications in the realm of the true bolt-on. Whether or not you want to try and sneak it past your local tech officials is up to you. Then again, if you’re a Vet who races in an age-defined class, it’s no problem at all.

In addition to the Cylinder Works Big Bore kit and Vertex piston, Clark also went with a Hot Cams Stage 2 intake cam and a complete FMF Racing exhaust system to extract even more power. Hinson clutch plates and springs are housed inside that trick-looking cover of the same name.
In addition to the Cylinder Works Big Bore kit and Vertex piston, Clark also went with a Hot Cams Stage 2 intake cam and a complete FMF Racing exhaust system to extract even more power. Hinson clutch plates and springs are housed inside that trick-looking cover of the same name.

The good news is that Clark’s game plan is an economical way to extract more power from the RM-Z250. For $679.95—and we’ve seen some outlet discount it as much as 30%—the Cylinder Works Big Bore kit comes with everything you need to bump the displacement of your stock machine. The foundation of the kit is a brand new cast-aluminum nickel silicon carbide (NSC) electroplated, 3mm oversize cylinder. NSC is a composite of a nickel and silicon carbide, and Cylinder Works claims that it offers excellent wear resistant surface with superior oil retention capabilities. All Big Bore cylinders are diamond honed to the exact bore dimension and proper surface finish to ensure the best possible ring seal. The kit also includes a forged Vertex piston. Constructed of 2618 aluminum alloy, each piston is hand-matched to fit each Cylinder Works cylinder before the kit is shipped. The kit also comes with all of the necessary gaskets to facilitate a complete top-end rebuild, including head, base and exhaust gaskets along with the necessary O-rings.

In an effort to give the engine a little more bark on top, Clark also opted to add a Hot Cams Stage 2 intake cam ($179.95) while he had the top end apart. Hot Cams Stage 2 cams are designed to provide more mid-range and top-end performance than the stock cams they replace. In this case, Clark went with the intake side only, as Suzuki redesigned the auto-decompression mechanism on the 2016 RM-Z250. Hot Cams should have a compatible Stage 2 exhaust cam available shortly. All Hot Cams are CNC-milled from 8620 billet steel and case hardened. The Stage 2 camshaft drops in to replace your stock cam for some of the easiest, most noticeable performance gains out there. The Stage 2 camshaft is a direct drop-in replacement for the RM-Z intake cam. The stock valve springs can be retained.

RMZ270-A-05112016

Other changes made in the engine department included the swap to a Suzuki RM125 two-stroke air filter cage to get rid of the backfire screen and allow more air flow into the engine and the addition of an FMF Ti Megabomb header ($349.99) and Factory 4.1 RCT Ti Muffler ($499.99). The Megabomb is designed to produce more low-end to mid-range power gains while also broadening out the mid- to top-end power gains over stock, and it’s also claimed to reduce sound output by as much as 1.5 decibels. The Factory RCT Ti Muffler incorporates FMF’s trademark Resonance Chamber Technology, which results in a shorter overall muffler length to help centralize chassis mass.

Just to be sure that the RM-Z250’s clutch was up to the task of managing the added power, Clark also installed Hinson clutch components, including new fiber plates, steel plates, springs and an outer cover kit. Once he buttoned everything back up, he also found it necessary to swap the stock Suzuki power coupler to the optional richer coupler to ensure that the now-larger engine was getting enough fuel before letting us swing a leg over the machine at Glen Helen Raceway. As most dirtbikers know, Glen Helen is home to the Southern California round of the Lucas Oil Pro Motocross Championship. It’s a fast track that is known for eating up a lot of horsepower. If the RM-Z270 kit didn’t cut the mustard, we would know soon enough.

The extra low and mid-range power was appreciated under acceleration, such as was needed for Robby Bell to clear the big uphill double at Glen Helen Raceway, but we were looking for more top-end power still.
The extra low and mid-range power was appreciated under acceleration, such as was needed for Robby Bell to clear the big uphill double at Glen Helen Raceway, but we were looking for more top-end power still.

Right off the bat, our guest tester Robby Bell proclaimed that the RM-Z had a lot more punch off the bottom and through the mid-range, no doubt thanks to the added displacement of the Cylinder Works kit. The added power down low meant that the RM-Z required fewer jabs at the clutch lever to maintain momentum, making the bike even easier to ride. And Bell seemed to have no trouble clearing the biggest jumps on the course, including a stout uphill double that was part of the track’s layout. However, he also noted that even with the Big Bore kit, cam and FMF pipe, the RM-Z didn’t produce the kind of top-end power one might expect. There was some noticeable improvement, but it was nowhere near as dramatic as the increase in the low-end and mid-range, which is not where the stock machine is lacking.

As much as we like the Cylinder Works kit, we believe that unlocking the RM-Z’s hidden power potential would definitely require cylinder head work. We would also love to try a full Hot Cams Stage 2 set when it becomes available for the 2016 RM-Z250. And, to be fair, Clark told us from the outset that he was sure that he could’ve had a lot more gains with good cylinder porting, but the original plan was to go strictly for true bolt-on mods.

Although the RM-Z270 has no trouble lofting the front wheel out of corners, we would still opt for cylinder head porting as a means to extract more top-end power from the Suzuki engine.
Although the RM-Z270 has no trouble lofting the front wheel out of corners, we would still opt for cylinder head porting as a means to extract more top-end power from the Suzuki engine.

RMZ270-D-05112016Of course, typical of a Jay Clark bike build, there was a lot more bling on the Suzuki RM-Z270 than we bargained for, but Clark always likes to go all out to showcase the products of the companies with whom he works. Function and style for the modified bike came courtesy of a host of companies, including Acerbis, which supplied a full set of its Flo Plastic bodywork along with a new rear chain block. DeCal Works custom graphics and a Moto Seat Custom Cool seat cover give the RM-Z a cool look all its own.

Up front, an Applied Racing billet triple clamp set locks down the Schmidt Performance-modified fork legs and Renthal 604 Fat handlebars complete with Renthal dual-compound grips, with the right grip covering a Motion-Pro Titan throttle tube. As is also typical of most of Clark’s builds, Works Connection supplied a host of trick bits, including Elite perches, a front brake lever, front and rear brake caps and radiator braces. Speaking of the radiators, they’re plumbed with CV4 hoses color-matched to the Suzuki’s yellow bodywork. CV4 also supplied a new high-pressure radiator cap to help keep the RM-Z from blowing its top.

The RM-Z270 rides on all-new rolling stock that includes a Tusk Off-Road wheel set that features an oversized 270mm front disc, along with a 270mm oversized rotor adapter bracket. Clark had the hubs powder coated gold to provide contrast to the wheels. A Regina MX Chain and a Renthal 48T sprocket are also used, along with Dunlop’s awesome MX32 rubber front and rear. Last, but not least, Clark fitted the bike with Pro Pegs titanium footpegs to give the rider a bit more grip.

When all is said and done, we would recommend the Cylinder Works Big-Bore kit to anyone seeking more low-end grunt and heartier mid-range performance out of their stock RM-Z250. For just under $860 plus the cost of the Hot Cams Stage 2 cam, the kit is an easy and relatively inexpensive way to make the RM-Z250 a more effective moto machine, even if the full potential of the Suzuki motor still isn’t realized.

RMZ270-L-05112016

Cylinder Works/FMF/Rocky Mountain ATV-MC Suzuki RM-Z270

Cylinder Works www.cylinder-works.com
3mm Big bore Cylinder Kit 269cc
Includes Forged Vertex Piston and Cometic Top-End gasket kit

Hot Cams www.hotcamsinc.com 515-402-8200
Stage-two intake camshaft

FMF Racing www.fmfracing.com
Factory 4.1 RCT Ti Muffler Ti Megabomb header

RMZ270-C-05112016Pro Pegs www.motostuff.com 503-830-6433
Titanium Footpegs

Acerbis www.acerbis.com 800-659-1440
Flo Plastic kit and rear chain block

Works Connection www.worksconnection.com
Elite perch
Front brake lever
Factory II stand
Front brake cap
Rear brake cap
Radiator braces

Applied Racing www.AppliedRace.com 800-853-0555
Triple clamp set

Dunlop Tire www.dunlopmotorcycle.com
MX 3S front 80/100-21
MX 3S rear 110/90-19

RMZ270-E-05112016Tusk Off-Road www.tuskoffroad.com
270mm oversized rotor/270mm adaptor bracket 270mm
Rear disc
Complete wheel set (powder-coated hubs finished separately)
Brake and sprocket bolt kits

Schmidt Performance www.schmidtperformance.webs.com
Suspension setup

Applied Racing www.AppliedRace.com 800-853-0555
Triple clamp set

Dunlop Tire www.dunlopmotorcycle.com
MX 3S front 80/100-21
MX 3S rear 110/90-19

Motion Pro www.motionpro.com
Titan throttle tube

RMZ270-F-05112016Renthal www.renthal.com
Rear sprocket, 48T
604 Fat handlebar
Dual compound grips

Hinson Clutch Components www.hinsonracing.com 909-946-2942
Fiber plates
Steel plates
Springs
Outer cover

VP Fuel www.hinsonracing.com 210.635.7744
U4.4 Fuel

CV4 www.cv4.net 800-874-1223
High pressure radiator cap
Yellow hoses

Rocky Mountain ATV/MC www.rockymountainatvmc.com
OEM Suzuki RM125 Air Filter Cage with no Back Fire screen

Uni Filter www.unifilter.com
Air filter

RMZ270-K-05112016Moto Seat www.motoseat.com 951-258-5229
Custom Cool seat cover

Regina Chain www.reginachain.net
MX chain

DeCal Works www.decalmx.com 815-784-4000
Semi-custom graphics kit
Pre printed number plates backgrounds

Just about every part listed above can be purchased from Rocky Mountain ATV/MC
Rocky Mountain ATV/MC www.rockymountainatvmc.com 800-336-5437

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