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Discussion Starter #1
Summary for those who want a quick fix conclusion:

I installed a Akropovic full titanium exhaust system, a BMC re-usable high-flow air filter, and DynoJet's Power Commander (PCV) and Autotune products on my 2012 R1200GS and went to the dyno room. The results:

1) I did three stock runs and the best was 104 rear wheel HP ("rwhp") and 82 ft-lbs of torque (the other two were 103 and change rwhp). The best post-mod run was 111 rwhp and 86 ft-lbs of torque (with a number of 110's). There was one run that actually hit 112 rwhp but it was spikey above 7,000 rpm (unlike the other runs which were more or less smooth), so we eliminated it as an anomaly. These readings, and all the readings below, are "corrected" to a reference external temperature and humidity baseline for consistency.

2) Of the 7 rwhp gain, about half was due to the Akropovic exhaust and the other half due to the Power Commander.

3) The high-flow BMC air filter provided no performance gains to the subject motorcycle. In fact, of the 20+ runs we did, only two were with the stock filter and it was one of these runs where the bike achieved 111 rwhp. If you're buying the filter for its reusability and wet weather utility improvements over the OEM paper filter, then you're buying it for the right reasons. If you've drank the Kool-Aid and are buying it to give you increased power, you've been suckered.

4) The airbox snorkel appears to be an integral part of the air intake design. Out of curiosity, we removed the snorkel, thinking it may restrict air flow through the already quite small air filter. We did two runs and both were in the 105 rwhp range, down 5-6 rwhp from our high run.

5) Removing the db-killer (baffle) from the Akrapovic slip-on had no discernible impact on performance.

6) 95% of GS/GSA owners - and I put myself in this category - would be satisfied going with just the Booster Plug or a similar ECU "fooling" mechanism. Only those that want that post-6000 rpm "turbo boost" effect need bother with the PC-V. That being said, a PCV without the Autotune can be gotten for $300 street price, and this is really all you need providing you can find a map that matches your motorcycle configuration.

7) The boxer engine was very temperature sensitive - the best readings we achieved in the "high four bar" temperature range. Runs in the three and five bar temperature ranges consistently turned in sub-par results.

The Long Story

Two things bothered me about the mechanical performance of my new R1200GS - the low speed lurching and decel popping, and the inherent vibration that kicks in at at 4200 rpm. "Bother" might be a strong term because both issues were more minor irritants rather than game breakers, but they were two issues I wanted to address. I had no urge to make this bike a track demon, so high-rpm horsepower gains weren't overly influential in my decision.

I previously had a Moto Guzzi Stelvio that had similar engine performance issues caused by leaning fueling, and people raved about how the PC-V gave the bike a completely new character, so I knew that was a (expensive) solution to the first problem of low-RPM performance. However, through this forum I also because of the Booster Plug, which at $150 was a much more cost effective solution to the same problem, but did not address the 4200 rpm vibration issue. I had no urge to make this bike a track demon, so high-rpm horsepower gains weren't overly influential in my decision. Having time on my hands,

I decided to splurge for the Power Commander in the hopes of adding additional power in the mid-range to hopefully drop the rpms below 4200 at my highway cruising speed of 120 kmh. I paid $520 for the R1200GS PC-V and AT-300 dual-channel Autotune device from Revzilla after a price match. The AT-300 has two O2 sensors so I could tune each cylinder independent of the other. The other advantage of the Power COmmander is that it enables you to have two maps, so I can set one map for every-day use (towards the power side in the non-cruise range) and second, leaner map to improve fuel economy on longer highway journeys. Creating the second map would be a snap with the Autotune.

I will also add that I swapped the stock header and slip-on for Akropovic's full titanium exhaust system and added a BMC re-usable high-flow air filter. The logic behind the air filter mod was that if I was opening up the back end, I don't want the engine to be choked by the filter. The Akropovic exhaust was $1,150 from Revzilla and the BMC air filter was something like $40 from a Texas sportsbike shop. The Akro titanium exhaust system is amazingly light and eliminates the catalytic converter. Based on my crude kitchen scale measuring methodology, the 13 lb titanium system cut about 9 lbs off the stock exhaust system. As an added benefit, the catalytic converter will no longer be boiling my gear box oil.

Total performance improvement outlay rings in at $1,700 (ouch!).

Given I couldn't find any before-and-after comparisons on the 'net, I decided to suck it up and spend money for the extra dyno time to dyno the bike before I did my mods. I was also determined to quantify the impact of the BMC high-flow air filter. It cost me an extra $200 in dyno time, so donations are welcome (haha - just joking - but feel free to make donations to the running of this forum).

Motorcycle: 2012 R1200GS
Mileage: 5,000 kms (3,000 miles)
Engine oil: Some cheap value brand 5W-30, topped up with about a litre of Castrol GTX 10-W30 (all dino oil)
Gearbox and final drive oil: Redline 75W-90 synthetic
Dyno manufacturer: Mustang
Dyno owner: Lentech Automotive Performance (changing name to be Richmond Motorsports)

I went to Lentech Automotive Performance on August 31 with my stock R1200GS and did three initial dyno runs for the sole purpose of benchmarking the performance attributes of the mods I was going to make, namely the upgrade to the Akropovic titanium full exhaust and a high-flow after market air filter (I went with BMC, but actually had both to choose from). Lentech typically does sportbike dynoing because that is where the demand is, although they have done a few cruisers. My bike was the first dual sport to show up at the doorstep, and upon my return trip, it as the first bike caked in mud that showed up at their doorstep.

We did three pulls and all three were fairly consistent - 103, 104, and 103 rwhp, respectively, with all runs generating over 80 ft-lbs of torque. The two dyno operators were shocked at the level of torque the motor put out. They see very few bikes hit that mark, the last one being a souped up litre bike that put out 194 rwhp and just cracked the 80 mark.

Off I rode home to add my mods. The titanium full Akro system is pretty sweet. Installation was quite simple and I love the sound. It isn't much louder than stock, but has a lower grumble to it. I then installed the Power Commander and Autotune. This was a little more challenging as the there are six wires from each of the Bosch oxygen sensors to connect, as well as the Autotune/map switch. To compound matters, I have my Adventure Designs tool kit and FuzeBlock under the seat, so I had to innovatively jam the PCV/Autotune against the throttle linkage box under the tank. This entail taking body parts off and the big bolt on the left hand side that secures the tank to the bike. Note to readers: if you have to take this bolt out, make sure you don't have a full tank of gas!

The PCV comes with a map for the stock GS. Fortunately DynoJet had a map on its website for a US bike with a full Akro system and stock air filter, so I grabbed that. Turns out it was almost a perfect map for my bike.

After the installation of the mods was complete, I took the bike for a spin. My Fat Ass dyno certainly noticed the power pick-up as soon as it hit 6,000 rpm. The first time I cracked it wide open throttle, the bike nearly ripped the handlebars from my grip. It is literally like somebody threw the nitro switch at the engine crested 6,000 rpm. What an amazing feeling!

I went back to the dyno today, September 12. I was intending to do the following runs to determine the performance attribution of each mod:

1) Akro exhaust with BMC filter, PCV disconnected
2) Akro exhaust with BMC filter, PCV engaged and custom map
3) Setup as in 2) but with the OEM air filter

We did two runs for setup #1 and hit 107 rwhp, up about 3 from stock. I forgot to get the graph so I don't have the exact number or the torque number.

With setup #2 we did two at 107, two or three runs at 110 and another at 112 rwp. The 112 run was quite spikey from 6,000 to redline, looking like a Bart Simpson haircut. Because of this we decided to disregard the results. The dyno operators again expressed admiration at the amount of torque the engine put out.

This is about when we first noticed that the performance of the boxer engine was highly temperature dependent. The best runs came when the engine was in the "high four bar" range, meaning just before the oil temperature gauge moved to five bars. Runs at three bars were consistently about 10-12 rwhp low (i.e. in the high 90's). Runs at five bars were typically around 4-5 rwhp low of the highs. The optimum readings all came during runs when the engine had been in the four bar range for a bit, and typically in the second or third run (we typically did three runs whenever we made a change to ensure we eliminated any abnormalities.)

At this point we determined that the max HP was 110. We then spend some time attempting to modify the torque curve in the mid-range from 4600 rpm to 6200 rpm (see the dyno chart below). We tweaked the fueling a few times but could only manage to slightly reduce dip. We then surmised that the the dip was caused by one of two factors, or a combination of the two:

1) ignition timing; and/or
2) actuation of the flapper valve by the ECU.

Dynojet has a module you can buy to tinker with the timing, but I didn't want to go there. With respect to the flapper valve, it could have been replaced by a straight pipe (Wunderlich makes one) or we could have disabled it in the "open" position.

I was a bit curious as to the impact of the high-flow BMC re-usable air filter over stock. I had read in a number of forums that there was no meaningful impact, but never saw any facts supporting this position. So we decided to pull the BMC and put in the OEM filter and did three runs. We did 108 and 109 rwhp runs, and followed these up with a 111 rwhp run, which became the new high of the day! One caveat here - when we did the runs after the filter swap, we didn't replace the fairing. This allowed the cooling fans to blow directly up the snorkel, possibly providing a "ram air" effect.

I found this pretty conclusive evidence that "high-flow" air filters from K&N and BMC have little to no performance impact, but may still be worth buying as the re-usability factor will save you big bucks in the longterm. They are also beneficial as they allegedly continue to function when wet whereas paper filters break down. On the other hand, there are many posts in forums indicating that these high-flow filters are not recommended if you're doing significant dusty off-road riding because they tend to pass a lot of dust compared to the OEM paper filters

We then began discussing the size of the filter and the narrow snorkel. The dyno operators noted that the GS air filter was the smallest they've ever seen, and also found that the long, narrow-entrance snorkel may compound the problem of the engine being air-starved. So we removed the snorkel completely, and just had the BMC filter sitting in the airbox (again, with the fans blowing into the air filter). We did two runs, both hitting 105 rwhp. We then surmised that snorkel design was an integral part of the engine design and not to be messed with!

And with that my dyno session ended. I got my charts and rode home $350 broker.

Here's the dyno chart of my best stock run contrasting against the best run with the mods (the one with the stock air filter).


2,923 Posts
Great write up. Thanks for spending the time (and money!) on this. I know where I'm going to send people the next time the "air filter change for better performance" issue is raised.

6 Posts
I did the same to mine (since sold) and it will remain the smoothest running motor I've ever owned. If a buy another GS in the future I will do the same to it.

2 Posts
A K&N filter should give you some hp boost.

I kinda did the same on my 2008 R1200GS, only with a K&N air filter and a full front to back open BOS exhaust sytem, and i used a Rapid Bike instead of a power commander.

I got to 117 Hp, but i'm not sure thats on the rear wheel (prob not).

3 Posts
Im not an expert, but from what ive read it would be harder to get two dynos to read within 5hp with the same bike, than it would be to get two bikes within 5hp on the same dyno!
What im trying to say is dont get hung up on figures from someone else. Dynoing bikes all over the world (or even in different towns) is not consistant
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