Hard Engine braking on 939

Yes, it's hard , usually with a aftermarket exhaust it will make the engine brake a bit smoother (specially removing dBkiller), but do not expect a 50% less than stock, you will get used to it really fast, you'll see.

IMO, engine brake is lower on testastretta engines than in my previous 696 (2-valves cylinders).

Give it some time before throwing money at it. The engine will break in, and you will adapt with a combination of gear selection, clutch and throttle. It will become a tool you can use. Engine braking is a function of the throttle plate design - don't see how anything short of changing that will change this characteristic.

Have you ridden a 2 cylinder bike of similar displacement before? Twins tend to have much stronger engine braking than 4 cylinders.

I highly suggest removing (or disconnecting) the exhaust flapper. IT really helped smooth out the engine braking for me. Unlike the 821, the 939 needs a servo emulator to prevent a check engine light from being thrown. An aftermarket exhaust will be next, but this is a great place to start. It is insanely easy to install and very reversible.

This is the one I used. Excellent product and Bernard has amazing customer service.

vizi-tec - Ducati exhaust valve eliminator

robbub said:

I highly suggest removing (or disconnecting) the exhaust flapper. IT really helped smooth out the engine braking for me. Unlike the 821, the 939 needs a servo emulator to prevent a check engine light from being thrown. An aftermarket exhaust will be next, but this is a great place to start. It is insanely easy to install and very reversible.

This is the one I used. Excellent product and Bernard has amazing customer service.

vizi-tec - Ducati exhaust valve eliminator

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Engine braking is purely a function of throttle plate design. I think there are a couple of factors here: engine braking and fueling.

By disabling the flapper I think you are affecting the fueling. My guess is that scavenging is affected, and power is diminished so the bike feels smoother.

Regarding engine braking: think of this: A diesel truck has a massive compression ratio, a huge engine, but no throttle plate - it has NO engine braking. The jake brake was invented to simulate this.

In the end, ducati has engineered the bike to be a certain way - coming from a Honda, I was taken aback. I learned which gear to be in for the situation, when to feather the clutch, and to be very aware of what my throttle hand was doing. It all dropped into place over time.

appliance821 said:

Engine braking is purely a function of throttle plate design. I think there are a couple of factors here: engine braking and fueling.

By disabling the flapper I think you are affecting the fueling. My guess is that scavenging is affected, and power is diminished so the bike feels smoother.

Regarding engine braking: think of this: A diesel truck has a massive compression ratio, a huge engine, but no throttle plate - it has NO engine braking. The jake brake was invented to simulate this.

In the end, ducati has engineered the bike to be a certain way - coming from a Honda, I was taken aback. I learned which gear to be in for the situation, when to feather the clutch, and to be very aware of what my throttle hand was doing. It all dropped into place over time.

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I see what you are saying about fueling being affected, but I have a hard time believing that the flapper has no effect on exhaust back-pressure. At lower revs, the flap is closed...doing almost exactly the same thing that a jake brake does on a diesel. I also get that at idle it is meant to be open, but there is certainly some crossover in the transition between throttle positions.

robbub said:

I see what you are saying about fueling being affected, but I have a hard time believing that the flapper has no effect on exhaust back-pressure. At lower revs, the flap is closed...doing almost exactly the same thing that a jake brake does on a diesel. I also get that at idle it is meant to be open, but there is certainly some crossover in the transition between throttle positions.

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Sure - but back pressure is different than engine braking.

I'm not an engineer I just play one on the internet, but I've had mufflers fall off cars and power dropped a lot.

I think what happens is that there is overlap between when the exhaust valve closes and the intake opens. At this point the decreased back pressure results in both the exhaust and initial gas charge being sucked out. The remaining charge is less - lower power, perceived smoother operation.

Machines with decreased back pressure have to be tuned to compensate for it. Just removing the flapper won't do this. Also, from what I've read, the flapper isn't just open and closed, it varies with operating conditions.

I guess I'm just saying the OP should ride and get used to the bike, and after a year or so, if he wants do modify stuff, have at it. I found that after a year, I was just riding the bike and using what it offers. A sharp throttle and engine braking - I'm set up for a curve without touching the brakes - in town I short shift to 3rd and things smooth out, bang down the gears - a touch of rear brake - and I'm ready for the next run - etc.. Don't baby it.

Ducati isn't the answer to everything, but they've engineered the dynamics of the bike pretty carefully- sharp and precise. I'd be leery of trying to turn it into something it's not, before understanding what it is. I was very happy with my Honda, and the duc was a shock - I adapted, it broke in, and excepting some mutually cantankerous moments, it's a pleasure to ride.

Stradaphil said:

Well I bought a new 939, and this is my first DUC. I have about 750km on it and I find this bike to engine brake hard when I let off??? Is this normal?? I find it really annoying. Now I've tried it 2 modes urban/touring although less in touring mode but still substantial engine braking?? Anyone else out there find this with the 939 or 821?? Or is it just me?? Lol thanks

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My 821 has the same issues, jerky throttle and very hard engine break that kicks in very suddenly. I've got another Ducati that doesn't have these issues, so it has been annoying me from day 1 (although not enough to sell the bike).

I tried some of the things that people tend to recommend. Disconnecting the exhaust valve made no noticeable difference at all, it only improves noise in idle slightly. I've also added an aftermarket exhaust (SC Project Oval, with db killers removed). Again, no noticeable difference in rideability.

Today I picked up my bike from the latest oil service and I also asked them to replace the front sprocket with a 14t one (stock has 15t). What a difference! It has become a completely different bike, acceleration is so much smoother now and the harsh engine brake has almost disappeared entirely. So much more rideable now.

I suggest you try the same, it's very inexpensive, shouldn't void your warranty (it's a common mod for Ducatis) and it's reversible if you don't like it. You don't even need to shorten the chain, just slightly increase the wheel base for the new sprocket, and that's it.

+1 on 14T front sprocket. I love the way the bike rides so much more with it. Coupled with disconnected exhaust flapper and an Akra slip-on it has truly become my favourite bike I've ever owned.