New Intake

I've been working on a custom intake system for my Monkey 125. Originally, I had the air filter mounted directly to the Takegawa big throttle body. It worked fine, but I wanted to design a proper intake system that would accomplish three things:

1. Taper from 43 mm ID (Air Filter) down to 34 mm ID to match the throttle body.
2. Built-in crankcase breather connection.
3. A dedicated mounting point for the IAT sensor.

There was another important reason I wanted to make my own intake. The stock airbox covers the cutout for the idle circuit, and even the connecting hose supplied with the Takegawa big throttle body does the same thing. Since I had removed the airbox, I wanted my intake to replicate that setup and properly cover the idle circuit.

The photos above show the final prototype I 3D printed. As you can see from the other photos, there were quite a few iterations to get to this point.

I've now sent the final design off to PCBWay for SLS printing in PA12 + 35% GF. I've also included a cross-section so you can see how the intake tapers internally.

Over Racing Lower Legs + Brembo Hypure 4P

The front-end upgrade is also coming along nicely. I've got the Over Racing lower legs paired with the Brembo Hypure 4-piston calipers.

I most likely won't get everything installed until around mid-October, as I'm waiting on a few additional parts so I can do a complete rebuild of the front forks at the same time.

But damn... this is going to be so good when it's finally together!

💡 Tip: Use coupon code Monkey125 at Webike Japan for 5% off your order.

We’re making progress! The custom steering stop from PCBWay arrived today, and it fits perfectly. The steering lock still functions as intended, and I now have plenty of additional clearance around the Brembo master cylinder.

Next up, tackling the brake lines. Once those are sorted, this Brembo upgrade project will finally be complete!

💡 Tip: Use coupon code Monkey125 at Webike Japan for 5% off your order.

The downside of removing OEM parts is that you also lose all the factory cable mounts for things like the O2 sensor wire, spark plug lead, ABS sensor wire, etc.

Cable ties get the job done, but I've never liked how they look, and they always made the bike feel like it wasn't quite finished. Since I finally have a 3D printer, I decided to design and print my own cable clips instead. They keep everything tidy while looking more OEM.

The last photo shows just how many iterations I went through to get the spark plug lead clip right. It took a few attempts, but I'm happy with the final version.

💡 Tip: The Webike Japan summer sale is on! Ends 30/07/2026

• Use code 26SM50 for 5000 JPY off on orders over 60,000 JPY
• Use code 26SM20 for 2000 JPY off on orders over 25,000 JPY
• Use code Monkey125 for 5% off on orders over 10,000 JPY

I love my Over Racing swingarm, but it lacks any sort of cable management for the rear brake line. I picked up a 3D printer this week and decided I wanted to fix that.

I also printed a cable clip for the oil catch can hose. Originally, I was using P-clips here, but I was never really happy with how they looked.

Simple little additions, but they clean up the bike nicely.

💡 Tip: The Webike Japan summer sale is on! Ends 30/07/2026

• Use code 26SM50 for 5000 JPY off on orders over 60,000 JPY
• Use code 26SM20 for 2000 JPY off on orders over 25,000 JPY
• Use code Monkey125 for 5% off on orders over 10,000 JPY

I mentioned in my previous post that the Brembo RCS 19 Corsa Corta was hitting the inside fairing at full lock when I positioned the lever at my preferred angle.

I looked at the steering stop sold by Norton Motorsport, but it seems to completely eliminate the steering lock. Fair enough, it's designed for track use, not the street.

So, what to do? Why not design my own? The goal was simple, create a steering stop that allows the lever to angle down further while still retaining the factory steering lock. After a few design iterations, I managed to get the lever angle exactly where I wanted it, and the steering lock still functions as intended. The lever just clears the inside fairing... like 1 mm, but it works!

The design has now been sent to PCBWay to be CNC machined from aluminum. Looking forward to seeing how the finished part turns out.

💡 Tip: The Webike Japan summer sale is on! Ends 30/07/2026

• Use code 26SM50 for 5000 JPY off on orders over 60,000 JPY
• Use code 26SM20 for 2000 JPY off on orders over 25,000 JPY
• Use code Monkey125 for 5% off on orders over 10,000 JPY

Personally, I like the tyre pressure sticker, but I'm still on the fence about the chain sticker. Does it give off a nice OEM+ vibe, or does it just clutter things up? Keep it or keep it clean?

💡 Tip: The Webike Japan summer sale is on! Ends 30/07/2026

• Use code 26SM50 for 5000 JPY off on orders over 60,000 JPY
• Use code 26SM20 for 2000 JPY off on orders over 25,000 JPY
• Use code Monkey125 for 5% off on orders over 10,000 JPY

Finally got the Brembo RCS 19 Corsa Corta installed to pair with the Brembo M4 monoblocks, and all I can say is... wow.

The braking power is absolutely insane. The initial bite is strong, but there's so much more control and feel compared to stock. If my ZX-4RR didn't have ABS, I'm pretty sure the first hard stop would've sent me over the handlebars.

Installation was pretty straightforward overall. The only issue I ran into was fairing clearance at full lock with my preferred lever angle, so I had to compromise slightly on the positioning. Norton Motorsport makes a steering stop for the ZX-4RR, so that's something I'll be looking into next.

As a small bonus, the swap also shaved about 100 grams off the bike. It's not a huge weight saving, but every little bit counts.

Next on the list will probably be a set of custom HEL brake lines to finish off the setup.

💡 Tip: The Webike Japan summer sale is on! Ends 30/07/2026

• Use code 26SM50 for 5000 JPY off on orders over 60,000 JPY
• Use code 26SM20 for 2000 JPY off on orders over 25,000 JPY
• Use code Monkey125 for 5% off on orders over 10,000 JPY

Front calipers are on, and wow they stop hard! The braking power is fantastic. They do work with the stock 14 mm master cylinder, but I wouldn't recommend keeping it that way. The lever travel is noticeably longer than I'd like, even though the brakes still feel strong and inspire plenty of confidence.

The stock brakes work very well for what they are, but these Brembo's are on another level. They're slightly lighter than stock as well but it's like 60 grams total.

Next up is a Brembo 19RCS Corsa Corta master cylinder, which I'll be ordering this week to give the calipers the master cylinder they deserve.

💡 Tip: Use coupon code Monkey125 at Webike Japan for 5% off your order.

I've been playing motorcycle mechanic all weekend, but it was definitely worth it.

After months of waiting, the engine is finally back together and running again. I upgraded from the 181 4V to the 181 4V 5-Axis setup. This kit claims to have slightly more top end power.

While I had it apart, I finished off my custom oil catch can setup and swapped the oil lines for the oil cooler over to braided stainless steel.

I only got about 5 minutes of riding in today, basically just around the block, but it put a huge smile on my face. I've really been missing this bike, and it feels great to finally have it back on the road.

💡 Tip: Use coupon code Monkey125 at Webike Japan for 5% off your order.

Just finished installing the rear Brembo P34 caliper using the Over Racing mount that I purchased from Webike Japan.

The swap ended up saving 337 grams. Not a huge amount on its own, but every little bit helps, and it's a nice improvement over the stock setup. Plus, I think it looks way better than the cheap bulky 1 piston nissin caliper.

Next on the list:

• Install the front Brembo calipers
• Replace the brake lines (currently leaning towards a custom HEL lines)
• Upgrade the master cylinder to a Brembo unit

💡 Tip: Use coupon code Monkey125 at Webike Japan for 5% off your order.

Hello fellow Monkey Bike enthusiasts,

Thank you to everyone who has used my coupon code Monkey125 over the last year. Your support has been amazing, and I'm excited to share that I've become a Webike Official Partner!

What does this mean? My coupon code Monkey125 has been upgraded and now gives 5% off orders over ¥10,000 at Webike Japan.

I thought I'd share the first photo I took of my Monkey 125 when I picked it up back in 2019. It's hard to believe how much the bike has changed since then! The plan was always to modify it, but this year the build has gone to a whole new level.

Thanks again, everyone. I couldn't have done it without the Monkey community! And if you have any questions about Webike, feel free to message me.