Tested: JGRMX Suzuki Stage 2 Kits | RM-Z250 and RM-Z450 4

Using the same parts and built by the same guys as the race team, these Suzuki engine kits are just what the RM-Zs needed.

 

Do you want to have the same motor as Hill, Martin, or Peters? That is a bit of an overstatement but, as you might have seen in this introductory video, the same guys that are building JGRMX’s race machines are working on the Stage 2 Kits you can buy for your RM-Z250 and RM-Z450. 

Suzuki has taken a lot of heat for not updating either bike for 2020, but JGR has picked up the slack with their performance parts. We’ve asked Suzuki and JGR if these kits and parts are aimed at being sort of the Suzuki version of Yamaha’s GYTR parts. They said yes and no. Eventually, with more time and development, maybe JGR could branch out and make even more performance parts for the yellow bikes, but right now they are a race shop, not a parts manufacturer. 

While we only rode the bikes with the Stage 2 Kits, here is a look at the difference between Stage 1 and 2 from JGRMX.


JGRMX SUZUKI STAGE 1 KIT

2019-‘20 SUZUKI RM-Z250: $1,049.99

2018-‘20 SUZUKI RM-Z450: $1,179.99

Boost overall horsepower and improve engine tuning ability with the JGRMX Suzuki Stage 1 Kit. The kit contains JGRMX’s proprietary high-compression piston kit, along with a GET RX1 PRO ECU. The ECU comes pre-programmed by JGRMX’s engine experts, with two maps that are designed specifically for JGRMX’s performance modifications. A map switch mounts to the handlebars and allows the rider to easily toggle between maps.

  • Piston boosts engine compression (RM-Z250 - 14.25:1; RM-Z450 - 13.5:1)
  • Two-ring design provides less drag and more horsepower
  • Forged piston for increased durability
  • Machined valve pockets for additional valve clearance
  • JGR logo etched on the piston crown
  • ECU comes pre-programmed with two map options (mapped for VP Racing T4 fuel)
  • Plug-and-play with immediate performance benefits
  • Maps developed specifically for JGRMX engine modifications
  • Kit includes high-compression piston, rings, DLC coated wrist pin, clips, and GET
  • RX1 PRO ECU (with WiFi-Com, two-position map switch and installation instructions)
  • Available for the 2019-‘20 RM-Z250 and 2018-‘20 RM-Z450

JGRMX SUZUKI STAGE 2 KIT

2019-‘20 SUZUKI RM-Z250: $3,349.99

2018-‘20 SUZUKI RM-Z450: $3,549.99

For the ultimate performance advantage, the JGRMX Stage 2 Kit contains the components necessary for success on the amateur ranks and professional level. The kit contains the JGRMX ported cylinder head assembly, JGRMX-spec race camshafts installed, as well as a pre-programmed GET RX1 PRO ECU and JGRMX high-compression piston kit. The Stage 2 Kit bolsters engine horsepower throughout the entire RPM range without sacrificing durability.

  • CNC ported cylinder head
  • Developed by the JGRMX race team
  • Fully assembled by JGRMX engine techs and ready to install
  • Kit includes assembled cylinder head, JGRMX-spec camshafts installed, GET
  • RX1 PRO ECU (with WiFi-Com, two-position map switch and installation instructions), JGRMX high-compression piston kit, head gasket, base gasket and NGK spark plug
  • Uses stock valve train and cam gears (valve springs are appropriately shimmed [450] or exchanged for proper valve control [250])
  • JGR logo engraved on side of head
  • Includes head gasket, base gasket & NGK spark plug
  • Hinson clutch springs are suggested
  • Requires the use of VP Racing T4 fuel
  • Available for the 2019-‘20 RM-Z250 and 2018-‘20 RM-Z450

On The Track

We can’t speak about the installation or any of the fitment because Suzuki/JGRMX invited us out to ride already built bikes. They had both stock RM-Z250s and 450s for us to ride to remind us of the baseline, then bikes with the Stage 2 Kit installed. 

RM-Z450 Stage 2 Kit

We first rode the RM-Z450s and there was a huge difference between the stock and moded bikes. The stock RM-Z450 has a solid motor but it isn’t that exciting. There is strong bottom and mid-range power, but it is delivered in a slightly old-school, chuggy sort of way. Then it sort of runs flat on top. 

The Stage 2 kitted motor is night and day different than the stock. From the first kick, it felt and sounded different. Twisting the throttle, not only was the power instantaneous and quicker reving, it was a lot freer feeling compared to stock. Hoping on the track, each gear revved out farther and at Perris, which is a tight jumpy track, we rode mostly in second gear. But, if you wanted to be super lazy, you could leave it in third and the instant, snappy throttle response would not have you reaching for the clutch. 

We wouldn’t describe the power as explosive, and that is a good thing because it is extremely difficult to control an explosion. The power changes rpms much faster than stock, but it is also very controllable and it even seemed easier to keep traction, even with a dry track. Overall the quicker, snappier, freer-revving engine made the RM-Z450 easier to ride fast and also made the machine feel lighter because of how responsive it was. 

RM-Z250 Stage 2 Kit

With the modified RM-Z250, we had two maps to play with (on the 450, Suzuki only loaded one) but neither maps made as much as a change from stock as we noticed on the 450. First, we’ll talk about map one, which was our preferred map of the two. From the first section of the track we could tell that the power delivery was different than stock. 

Like it’s bigger brother, the stock 250 has a bit of a bottom-heavy power that lacks a bit of snap and excitement. Map one brought in some excitement by letting the motor rev a little quicker and have better response, but it still didn’t have that free revving feeling that the 450 had. What it did do was get the engine to continue making power throughout the rpm range and let us use all of each gear, which is a big deal on a 250F. It also did this without taking away any bottom end or torque characteristic. 

Map two had a power curve closer to stock, but bumped up a few notches. Meaning, its power was still focused on the bottom end of the rpm, but it had a gruntier torque hit. With this map, the RM-Z250 still preferred to be short shifted but we were rewarded more by the ample bottom-end power. 

Both maps ran cleaner and sounded better overall than the stock engine, and there is a race-engine quality that isn’t so much that there was a ton more power, just that the bike had a more aggressive, responsive motor that made it more fun to ride. 

On The Other Hand

You can’t get something without giving something. With the JGRMX Stage 2 Kits, the first thing you give is money, because as you’ve seen above they are not cheap. You also give up the use of pump gas, because these kits require the use of race fuel (VP T4 is recommended). Just keep that in mind before dropping the dough on these mods. 

Overall

We are super impressed with these kits, especially on 450. We are also super impressed that JGR is even doing this, since Suzuki Japan has is taking a breather on its 2020 models. It is a smart move on JGRMX’s part and it really helps Suzuki, and Suzuki owners - in the end it is a win, win, win. Well, that is if you can afford it. 


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