Solve your problems with advice from an old style Grom (MSX125) owner! Custom parts for mountain passes and racetracks!

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Many people think that Groms are for beginners or only for street riding, but everytime I hear someone say something like this, I'm compelled to say otherwise. Many people recognize the fun of sport riding on the Grom. However, it is also true that it is difficult to ride in its stock condition. In contrast to the previous article for streets and touring, this time I will introduce what kind of customization is recommended for comfortable sport riding, based on my experience as an owner of an old style Grom.

Let's start with rearsets!

The stock step on the Grom is quite low and can easily hit the bank sensor when you bank to a certain degree. If this happens, we're not just worried about performance, because it's actually dangerous, so we recommend that you replace the steps with rearsets first.

OVER RACING: Rearsets

We recommend OVER RACING's rearsets from among the many choices out there. The most notable feature is their precision! When I installed one on my Grom it was easy to install and didn't rattle at all. It feels solid and motivates the rider as it raises your position. Above all, the shiny silver color is very cool!

Common to Type 1 and Type 2
Step position: 4 patterns
115mm back / 40mm up
120mm back / 50mm up
110mm back / 50mm up
105mm back / 40mm up
Shift: Regular shift
Pillion Step: None

BABYFACE: Rearset

This is a performance rearset kit from BABYFACE, a familiar name in the All Japan Championships. The bright gold color is eye-catching and the double bearing and knurling on the footpeg are designed based on feedback from racing experience. Please note that the position of the step and shift pattern are different between the JC61 and JC75.

Type 1 (JC61)
Step position: 4 patterns
142.5mm back / 72.5mm up
142.5mm back / 85mm up
155mm back / 72.5mm up
155mm back / 85mm up
Shift: Reverse shift
Pillion Step: None

Type 2 (JC75)
Step position: 2 patterns
87.5mm back / 37.5mm up
100mm back / 37.5mm up
Shift: Regular shift
Pillion Step: None

The handle position is too high! Let's replace the handlebar!

The stock handlebars of the Grom are very high up and close to the rider, which is a comfortable position for street and touring, but many people feel that they are a pain for sport riding. By replacing the handlebars, you can free yourself from such stress and enjoy a more flexible riding position.

HURRICANE: Forward Continental Type 2 Handlebar

This HURRICANE Continental Type 2 handlebar is the choice of many Grom owners. Compared to stock, it is 60mm down and 95mm forward for the Type 1 (JC61), and 40mm down and 65mm forward for the Type 2 (JC75), giving it a much lower forward lean position. The stock position is upright to begin with, so if you have experience riding other sport bikes, you may feel like the new position is actually more what you expected. This product is specially designed for the Grom, so there is no need to drill holes to stop the switch box from turning. Another great point is that it can be installed without changing the length of the brake hose or clutch wire. In other words, it can be simply bolted-on.

SP TAKEGAWA: Aluminum Handlebar Pipe

This handlebar is produced by SP TAKEGAWA. It is made of aluminum, which makes it lightweight, and it is slightly more upright than the above HURRICANE handlebar. It is also specially designed with drilled holes to save time and effort when attaching it. You do have to make sure you've got your brake hose and clutch wire routed properly though.

If you feel like your rear suspension is not up for the challenge, replace it!

The rear suspension of the Grom is not adjustable in terms of either preload or damping, which is a problem for riders who are particular about the way their bike rides. Reflecting this dissatisfaction, rear suspension systems by various companies are available, so we will introduce some of them here.

SHIFT UP: Racing Rear Shock G-1

The SHIFT UP rear suspension is notable for its cost-effectiveness. Even though it's priced in the 30,000 JPY range, it is equipped with specifications such as seamless preload adjustment, 14-level rebound damping, and 4-level compression damping, making it suitable for all kinds of situations. Moreover, it is equipped with a separate reserve tank! The spring rate itself will be a little stiffer than stock, but the aforementioned adjustability and excellent damper will surely improve ride quality. This is our No.1 selling rear suspension product for the old Grom!

NITRON: Rear Suspension Mini Shock MINI R1

Rear suspension by NITRON, a leading suspension manufacturer that needs no introduction. The turquoise blue spring gives off a racing atmosphere. The adjustment functions are also more than sufficient with 24-levels of both rebound and compression damping, and seamless preload. It is jam packed with knowhow cultivated from racing experience.

Address the Grom's weak point by reinforcing the front suspension!

The Grom's front suspension has a very soft feeling, which is fine on the street, but when hard braking is required, the disadvantages immediately show their faces. The replacement work is difficult, so this is generally a custom job you want to take to a professional bike shop, but what you get out of it is huge, so we will introduce some parts here.

KITACO: Front Fork Springs

KITACO's front fork springs are for those who want to dedicate themselves to riding on the mini-circuit! This product is available in three different spring rates, 5.5, 6.0, and 6.5, to suit the rider's skill level, weight, and riding conditions. (*The stock spring rate is 3.8N) By installing these springs, you'll be able to avoid those pesky nose dives and bottoming out the suspension! It is recommended to use KYB #30 fork oil when replacing the springs.

SHIFT UP: Reinforced Front Fork Springs

For those who do not brake that hard, but would like to make the forks a little stiffer than stock, we recommend these reinforced front fork springs from SHIFT UP. The spring rate is 4.2N, which is about 10% higher than the stock spring, and you can expect a milder ride than the above KITACO spring.

Too slow on the straights? Time for an engine tune!

Once you're done with the suspension, you'll feel like engine power is what you're missing. With the stock engine, it often loses in a straight race to other 125cc engine models. There are a lot of engine tuning kits for the Grom out there, so here are some of our recommendations.

KITACO: S Stage Alpha Big Bore Kit 181cc

The Grom has a reputation for being slow in stock form, but if you simply want to increase power, a big bore is the quickest way to do it. The 181cc S Stage Alpha Big Bore Kit from KITACO can increase output by about 4 horsepower with the exhaust and throttle body left in stock form. If you use an aftermarket exhaust and FI setting, you can get even more power, so you can dream big. This product comes as a set with everything needed, so you don't have to buy each part separately.

SHIFT UP: High Comp Piston & Cylinder Full Kit

For those who don't want to change the displacement, SHIFT UP's high-compression piston and cylinder full kit is the answer. With an aftermarket exhaust, high camshaft, and FI setting, you can expect a power increase of about 2.5 horsepower without changing the 125cc engine. Please note that the camshaft must be replaced before installing this product.

Customize your Grom for stress-free sport riding!

If you install the above custom parts and get the settings you like, you'll have more motivation to ride! You might even be able to outrun bigger bikes on the mini-circuit! There are also many other custom parts that we did not have room to introduce here, so check them out if you are interested.