Yamaha R9 M4 Exhaust Install

Yamaha R9 M4 Exhaust Install

The Yamaha R9 Gets an M4 Exhaust… and It Sounds INSANE!

You guys know I've been waiting to get my hands on the Yamaha R9, and today we finally had one in the shop for an exhaust install.

This customer wanted to get rid of the factory system and replace it with a full M4 exhaust. I was excited because I hadn't installed one on an R9 yet, and I wanted to see how Yamaha designed everything underneath the bike.

Plus, I knew that big M4 muffler was going to sound good.

And man, I was not disappointed.

One Last Listen to the Stock Exhaust

Before taking anything apart, we started the R9 and let it warm up for a moment.

The factory exhaust is pretty quiet. You can hear it, obviously, but it doesn't have the kind of sound that makes you turn around and go, "Holy crap, what is that?"

The customer wanted something with a little more personality, and I completely understand that.

We gave it one last listen, shut it down, and got ready to remove the factory system.

Why I Like M4

I've been using M4 exhausts for a long time.

They're right down the street from us, I do a lot of business with them, and they're good people who make good exhausts.

For the money, I think they offer excellent value.

I've got several exhaust comparisons planned for my own motorcycles, including M4, Spark, and Akrapovič systems for the R9. Once my dang R9 finally shows up, we're going to have a lot of fun testing those.

But today was about getting this customer's motorcycle done.

I Opened the Wrong Exhaust

So, we started unboxing the M4.

Everything was packed beautifully, just like I've come to expect. The components were wrapped, the hardware was protected, and the tubing and welds looked great.

I pulled out the headers and started looking at the numbers.

One. Two.

Wait a minute.

There are only two header pipes.

The R9 is a three-cylinder.

I looked at the box and realized I had opened the M4 exhaust for my R7.

Whoopsie.

I had completely forgotten that I left it over there with the other exhausts.

So, we packed that one back up, grabbed the correct R9 system, and started again.

That's what happens when you've got too many motorcycle projects going on at once.

Unboxing the Correct R9 System

Once we opened the right box, everything made a lot more sense.

Three header pipes.

A collector that brings the three pipes into one.

The muffler.

Mounting brackets, springs, and hardware.

And that muffler was a big old sucker.

I pulled it out and immediately thought, "Oh my God, that is going to sound good."

The tubing looked substantial, the welds were clean, and the overall construction was exactly what I expected from M4.

The header pipes were numbered, which makes installation easier. On this motorcycle, cylinder one is on the left when you're sitting on the bike, followed by two and three.

It's a simple detail, but it helps you keep everything organized.

The R9 Is Surprisingly Easy to Work On

One of the first things I noticed was how Yamaha designed the lower fairing.

I really like it.

Instead of having to take apart a bunch of separate panels, the lower comes off as one piece.

There were three fasteners on each side, and once I figured out how the panel released from its mounting points, it came right off.

I was like, "Oh man, this is going to be easy."

I hadn't done an R9 exhaust before, so I was taking my time and figuring it out as I went. I didn't want to force anything or break a customer's fairing.

Once the lower was removed, we had access to the exhaust mounts, oxygen sensor, and header nuts.

Removing the Factory Exhaust

The factory system has two main mounting points underneath the motorcycle, along with the header connections.

Before dropping the exhaust, I removed the oxygen sensor so we wouldn't pull on the wiring.

That's an important step. You don't want the weight of the exhaust hanging from an O2 sensor or its harness.

The bike was still a little warm from the sound test, so I had to be careful around the metal. If you're doing this at home, let the exhaust cool completely before working on it.

After removing the mounts and loosening the header nuts, I expected the factory exhaust to drop straight down.

Of course, it didn't quite work that way.

The Middle Flange Was Stuck

The exhaust was hanging up near the front of the engine.

I couldn't immediately see why, so I had to stop and assess what was going on.

It turned out the middle header flange was catching in a tight area. Once I worked that flange down and cleared the obstruction, the entire system released.

And holy crap, that thing felt heavy.

The important thing is that I didn't just yank on it. When something doesn't come apart the way you expect, take a look and figure out what's holding it.

That's how you avoid turning a simple exhaust install into a much bigger problem.

How Much Weight Did We Save?

I wanted to weigh both systems so you guys could see the difference.

The factory exhaust came in at approximately 7.3 pounds on our scale.

After assembling the M4 components for the comparison, the aftermarket system weighed approximately 4.45 pounds.

That's a savings of about 2.85 pounds, or roughly three pounds.

Not bad at all.

The weight savings are nice, but for this customer, the sound and appearance were probably going to be the biggest differences.

A Little Trick for Exhaust Gaskets

Before installing the new headers, I checked the exhaust gaskets.

You want to make sure all three are accounted for and that you don't accidentally leave an old gasket in place and install another one on top of it.

Sometimes the gaskets don't want to stay in the exhaust ports while you're trying to position the headers.

One little trick I use is a tiny dab of suitable assembly lubricant to help hold the gasket in place.

You don't need a ton.

Just enough to keep it from falling out while you get the header started.

Always follow the exhaust manufacturer's instructions and use the correct gaskets and approved products for the application.

Install the Headers, but Leave Them Loose

This is probably the biggest installation tip I can give you.

When you're installing a multi-piece exhaust, don't tighten everything down immediately.

I started with header number one, got the gasket seated, and installed the nuts just enough to hold the pipe in place.

Then I did number two.

Then number three.

I left all of them loose so the pipes could move slightly while I fitted the collector.

If you tighten the headers first, you can make it much harder to line up the rest of the system.

Get everything assembled and positioned correctly, then follow the manufacturer's tightening sequence and torque specifications.

Getting the Collector to Fit

The collector takes the three header pipes and brings them together into one outlet.

Pretty simple.

But getting all three pipes lined up at the same time can take a little patience.

Number two was giving me the most trouble.

I worked the pipes into position, pushed the collector on a little at a time, and used a rubber mallet for a few gentle taps.

You don't want to beat on the tubing. You can dent it or damage the joints.

Just a little bit of persuasion.

Once everything was seated, the collector lined up nicely with the mounting point.

And when I held the muffler up to see how it was going to look, I was like, "Ho ho ho. Merry Christmas."

That thing looked awesome.

Mounting the Muffler

With the collector positioned, we fitted the muffler and its mounting bracket.

I've installed a lot of M4 systems, so I had a pretty good idea of how the bracket was supposed to sit, but I still checked the alignment and clearance before tightening everything down.

Once the muffler was in place, we installed the springs.

One on the top.

One on the bottom.

And there it was.

Man, I liked it.

The muffler is big, the tubing looks aggressive, and the whole system gives the R9 a completely different appearance.

I could almost stick my fist in the outlet.

Except I don't have baby hands.

The First Start Was Worth the Wait

Now for the fun part.

We started the R9 with the new M4 system.

And immediately, I was like, "Holy crap."

The sound was completely different from stock.

It had that aggressive three-cylinder character that makes the R9 so interesting, and the M4 really brought it to life.

I was grinning like an idiot.

We didn't want to keep running the motorcycle inside the shop, so we shut it down and got ready to finish the final checks.

Exhaust fumes are no joke, and any engine-running test should be done with proper ventilation or outside.

Final Checks and Reassembly

Before putting the lower fairing back on, I wanted to go through everything one more time.

Check the header connections.

Check the collector.

Check the mounting hardware and springs.

Make sure the O2 sensor and wiring are properly routed.

Verify that the exhaust has the correct clearance from the fairings and surrounding components.

Then reinstall the lower and make sure everything is secure.

That's the part of the job you don't want to rush.

The exhaust might look finished, but the final inspection is what makes sure it's actually ready to ride.

More R9 Exhaust Testing Is Coming

This was a customer's motorcycle, so I didn't want to strip the entire bike apart just to make filming easier.

When my own R9 arrives, we're going to do a much more detailed series.

I've got multiple exhausts lined up, and I want to show you guys the installations, the differences in construction, the sound, and the dyno results.

I also mentioned in the video that M4 was working on an updated R9 exhaust. I'm looking forward to getting that version and showing you the differences compared with this earlier system.

The goal is to give you real information so you can decide what you want for your own motorcycle.

What Do You Think of the M4?

I'm really happy with how this one turned out.

The installation was straightforward once we got past that middle flange and lined up the collector, the weight savings were a nice bonus, and the sound was awesome.

But I want to hear what you guys think.

Do you like the big M4 muffler on the R9? Would you go with this system, or would you rather have something smaller and more tucked away?

Let me know in the comments.

Thank you guys so much for watching and supporting MotoBros. We've got more bikes coming, more builds, and a whole lot of exhaust testing ahead.

Please ride safe, grow your skill, and I'll see you guys in the next one.

Craig, MotoBros