E85 On The 2025 BMW S1000RR?! BT Moto Review

If you're into motorcycles and performance tuning, you've probably heard the hype about E85. But what is it, how does it actually work on a high-performance bike like the 2025 BMW S1000RR, and is it worth the switch from traditional pump gas?

Well, that’s exactly what we’ve been testing, and after thousands of miles and dyno pulls, we’re breaking it all down for you.

What is E85? 

Let’s start with the basics: E85 is an ethanol-based fuel, and the “85” means it contains roughly 85% ethanol. Compared to 91 octane pump gas, the air-to-fuel ratio required for combustion (what we call stoichiometric ratio) is drastically different. Ethanol requires a lot more volume to hit the ideal burn, which means your bike needs to deliver about 40% more fuel to maintain proper combustion when using E85.   

That sounds like a big shift — and it is. But the benefits are huge. E85 has an effective octane rating of around 110, and it absolutely loves high-compression setups, high cylinder pressures, and forced induction. That's why it’s a go-to choice for racers and tuners. It also happens to be cheaper than pump gas in many areas, which only adds to its appeal.

Closed Loop, Adaptation Limits, and Why You Can’t Just Dump E85 In 

Now, one of the most common questions we get is: “If full-time closed-loop fueling is enabled on the S1000RR, why can’t I just fill up with E85 and ride off?” It’s a fair question — and the answer comes down to limits.

While closed-loop systems can adapt to changes in fuel composition, there’s only so much adjustment they can make. On the S1000RR, adaptation caps out around 30%, and E85 typically requires more than that. So no — you can’t just dump it in and expect the bike to run optimally. You need a dedicated tune for E85, just as you need one for 91. The good news? Swapping between them takes less than a minute using our handheld tuner.

Not Every Bike Can Run on E85

Not all bikes are created equal when it comes to ethanol support. For older generations like the 2010–2019 S1000RRs, you had to upgrade the fuel pump just to run E85. The 2025 model? No pump upgrades necessary — just the right software, however we do sell a fuel pump if you want it for peace of mind.

That said, we don’t offer E85 support for every motorcycle. Yamaha R1s, CBRs, and others may technically “run” on it, but they lack the hardware and full-time wideband feedback needed for safe, consistent tuning. E85 fuel content can swing anywhere between 50% and 85% ethanol, depending on the pump, which drastically affects tuning. Unless the bike can compensate in real time (like the S1000RR does with its four O2 sensors — two wideband, two narrowband), we won’t touch it. Safety first, always.

Dyno Testing and Power Gains

So, what kind of power does E85 bring to the table? We strapped the 2025 S1000RR to the dyno and ran it with both fuels. At first glance, the dyno curves look similar, but once we adjusted for the new 44-tooth rear sprocket, the gains were clear: E85 was putting down 3 to 4 more horsepower across the entire RPM range.

​And this isn’t just about peak numbers — throttle response felt snappier, torque delivery was punchier, and the engine ran cooler thanks to ethanol’s natural cooling effect during combustion. The difference was noticeable in both performance and ride feel.

Is E85 Worth It? Cold Starts, Reliability, and Long-Term Testing

We’ve been riding the S1000RR on E85 for thousands of miles, and it’s been rock-solid. Cold starts have been flawless, and the bike has shown zero signs of poor behavior. As long as your tune is done properly — and that’s the key here — E85 is perfectly safe and reliable for daily or track use.

Now, you might’ve heard horror stories about E85 “going bad” or gumming up fuel systems. Let’s clear that up. First, modern flex-fuel vehicles have been using E85 for years without issues — GM and Ford, for example, have supported it in their stock vehicles. Second, any ethanol fuel can degrade over time, but this is rarely an issue unless the fuel is poor quality or the bike sits for nine months without starting.

If you’re still concerned, a simple solution is to “pickle” your fuel system. Run the tank low, switch back to 91, swap to your pump gas tune, and run a full tank through the bike. Do this every few months if you’re not riding frequently, and you’ll avoid any potential ethanol-related issues.

How to Switch Between E85 and Pump Gas

Well, switching between E85 and 91 pump gas is as easy as it gets. All you need is our BT Moto handheld tuner. When you get low on gas, fill up with your desired fuel, load the corresponding tune, and you're good to go. The only time the transition is a little rough is during those first few starts when switching fuels — you’ll need to clear out the old gas in the lines. But once you’ve cycled a bit of the new fuel through, the bike settles in perfectly.

That said, the only real downside of E85 is the reduced range. Because it takes more fuel to make the same power, your tank won’t last as long. But if you’re not on a cross-country trip, it’s a small tradeoff for the benefits you get.

Final Thoughts

E85 isn’t just for hardcore racers anymore. On the right platform — like the 2025 BMW S1000RR — it’s a powerful, practical upgrade that gives you more horsepower, better throttle response, lower temps, and even saves you money at the pump.

And in case you're wondering what bikes support E85 tuning, we currently offer E85 support for all Gen 4 BMWs — including the 2020+ S1000RR, S1000R, S1000XR, and even the R1250 and R1300 platforms. As long as your bike has a Stage 1 tune, we can provide an E85 map to go with it. The files are delivered just like any other tune — quick, seamless, and easy to switch back and forth on the fly.