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interesting observation (servo/exhaust valve)

22K views 38 replies 16 participants last post by  lucasjmatthews 
#1 ·
Two interesting observations,
Let me preface this by saying I’m still getting used to the bike only have 250 miles on her.
I had the bike out for a hour long ride last night and noticed every time I rolled on the gas the bike would hesitate for a split second.
And you could hear the exhaust muffled.
I thought to myself it maybe the servo/exhaust valve, so today before my trip to work I just disconnected the cable to the valve.
Wow what a difference. Not only is that hesitation gone but the bike sounds so much better cruzing around (part throttle).

Oh yeah, without that big rear fender on the back everything you run over ends up on your back…
 
#2 ·
So did you just ride around with the CEL on ?
 
#8 ·
With only 250 miles on the bike, the computer still hasn't fully "learned" your setup.
In fact, you can't truly judge the bike until the computer really learns the setup which is after the break in period, when you can run through the entire rpm range at full throttle.

When I changed out my pipes and air filter, the bike didn't really come alive until after about a hundred miles of blasting around country roads.
 
#9 ·
Thanks Tony, that is why I said I only have 250 miles. Agreed.
No CEL, and I just put another 20 on her at lunch today.

The range of motion is the same I checked it last night.
I can take a picture if you would like to see.

I will let you know if I get a CEL, I have a 23 mile ride home tonight.
 
#11 ·
Just to clarify, . . . are you disconnecting it at the motor, or at the mid-pipe ? Or does it not matter ?
 
#14 · (Edited)
Wow what a difference. Not only is that hesitation gone but the bike sounds so much better cruzing around (part throttle).
I noticed the same thing after I removed my valve; the bike seemed to sound much better at low RPM with the stock exhaust. Then I was informed by other members here (or on the DMF) that the exhaust valve is only closed when the bike is first started and at idle in neutral, and after that it remains open, so I figured I must have been imagining the improved sound.

**EDIT: I can't say I noticed any change in hesitation (or lack thereof), but I wasn't really looking for one
 
#15 ·
Hello Guys

Just a quick couple of questions.

Can someone explain to me the purpose of the In Line Exhaust Valve?
And what does CEL stand for? What is it? Something displayed on your dash?

I have this high pitched sound coming from my bike at 5000RPM, like a vibration or harmonics of the bike. At 5000RPM the valve would be 100% open right? Im thinking of detaching the cable to the valve as part of trouble shooting. Are there any long term issues with having this cable detached? Bike run leaner?

I think that might have been more than a couple of questions.
Sorry guys, new to ducati and all these extra moving parts.

Thanks in advance guys :)
 
#16 ·
Well the exhaust valve is for sound and emissions I believe, don't really need it. I recommend either getting your ECU reflashed or get a ducEE http://www.vizi-tec.com/duc-ee/

By doing this you can remove the cable and servo motor all together plus bike runs better. Oh and CEL is just an acronym for Check Engine Light
 
#18 ·
These bikes come very lean from the factory to meet emissions requirements. Although you don't "need" to reflash your ECU with slipons it will make it run MUCH better. http://motowheels.com/i-7185267-mw-tuning-rexxer-ecu-remap.html

Disconnecting the exhaust valve will give you the EXVL error code and then its a pain in the butt to get it to clear... at least it was for me. sensitive setup

The exhaust valve stays in the open position when the cable is disconnected. So no problems, better airflow... actually if you can get your hands on a 696 midpipe that would be ideal (no exhaust valve) but those are hard to find used/cheap
 
#19 ·
Thanks mate.

This is all getting confusing now :p

Other forums talk about the valve being closed at start to assist with cold starts and noise levels. Waiting for a response I decided to roll the bike out and observe the valve. On start it would check the valve, open - close or close - open. So I wanted to see what it would do if I disconnected the cable from the valve, the cable just moved up and down as expected and the CEL went off as per normal. So I started the bike and all worked as expected.
No EXVL errors or CEL errors. I am riding a Monster 796 2012, so I don't know if anything has changed.

I might take it for a quick run to see how she performs.

Question tho, if the valve is open to start with, why would it close it to restricted air flow above 4000RPM?

Cheers :)
 
#24 ·
I disconnected the cable at the flapper and rode for about 4 hours today. I honestly couldn't tell much of a difference, just very slightly. Either way, I'm glad it's open all the time now.
 
#25 ·
I removed the cable from the valve and when I turn the key on I hear the servo turn, albeit slower and longer it seems.
I did get a CEL pretty much straight away and it didn't go away until I reconnected the cable.
It did sound a little louder due to the valve being open and the bottom end did smoothen out slightly but not really that noticable.
My bike is a M795 btw with the 696 chassis and 796 engine.
 
#27 ·
I did not get a CEL either. Here is a picture of what I disconnected . . . You just have to take that cover plate off by removing the one allen screw. Then just rotate the flapper by hand to release the tension on the cable, and it will come right off.

 
#28 ·
I ended up disconnecting the cable at the valve as described by scottydoesnt. Didnt even take 5 minutes. Ive commuted all week on the bike and have gone on a couple of longer rides (today was about 130 miles) and have had no issues/CEL. Bike seems to be quite a bit smoother around the 4-5k range, the exhaust note is more consistent, and I dont get that weird hesitation from the valve closing.
 
#32 ·
It worked! Man! save even the cost of the Duc EE, simply disconnecting that cable made great improvements. Ok, so they may be minor, but they're huge to me bc I've only had it a week. And no Check Engine Light

Results:

Before: Throttle response was very twitchy. On my half hour ride to work, I felt like I had to get to the sweet spot in 3rd which was 4k rpm and around 45mph. First and second were gears to get through, not gears to ride in. Very twitchy up to the 4k mark.

After: First, I couldn't hear my music as well, so it must be louder :) Secondly, 1st was easier to more smoothly (still not perfect, but improved) roll off of at a stop and get to second gear. Second gear is smoothed out fairly tremendously really. I was able to cruise and roll on throttle fairly smoothly from about 2500 rpm through 4k. I specifically noted that this made 2nd gear usable in the 25 and 35 zones.

Great mod and didn't even require buying the Duc EE. Thanks guys!!
 
#34 ·
I am so glad I didn't spend $90 to have that kinked cable replaced. Mine is coming off too!
 
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