Baffles in or out ?

OK - you're going to have to bear with me & accept me for the idiot that I'm going to sound.  But in my defence, I've never owned a bike with FI - my last bike was 17 years old, with a single carb between the cylinders.

I've been riding my 2015 SE for a couple of weeks now, put on about four hundred miles.  On fast, open roads, it's great, but around town it's lumpy & needs plenty of revs.  Never having ridden a Guzzi in my life, I have no idea whether this is normal.  The bike is fitted with an Agostini Megaphone slip-on, which has a nice pop on over-run.  This afternoon I realised that it has a removable baffle which I popped out to see what would happen - the bike seems to run a lot better - smoother, slightly more responsive.  However, it is noisier & pops a lot more.

As I say, I know nothing at all about modern fuel systems, FI, removable baffles, etc.  What's the advantages of changing the end-can - is it purely a weight saving exercise, does it increase performance, or do people do it to make their bike louder ?

I'm guessing that the bike has to be set to run with either baffle in or baffle out - the bikes ECU is not clever enough to detect & compensate for removing the baffle without some changes to the set-up ?   Which is best way to go - in or out ?  

Any answers in "dumb-down" mode would be greatly appreciated

Dave

I'd think you need the bike mapped to match the exhaust system.

Beetle mapping my bike has been a revelation [You must be registered and logged in to see this link.]

Cheers,

Angus.

The stock GRiSO exhaust is very heavy. About 8.5kg IIRC. Replacing it definitely saves some weight, but I think most do it because they either hate the look or simply want louder.

The ECU does trim the fuel in the sub 4000 RPM range to meet emissions. However, it's slow and it will eventually go back to the way it was. The 8V does not work well with open exhaust. I would leave the baffle in. Pull the main fuses for a few minutes to reset the fuel trims. It will run better, for a while.

While no expert I found that leaving the baffles in with a Beetle map are the best way to get GRiSO singing. While I love the sound of an open pipe, the increase in fuel economy and beefing up of the midrange are just to good to give up for the pipe note. Do yourself a favour get the map and use the money saved on fuel to buy some nice black beer!

Right - so tomorrow I'll pull the 30 amps from under the seat & pop the baffle back in & see how how it goes.

Problem for me is that whilst I can wrap my head around basic mechanics, anything complex scares the life out of me. And using a laptop to tune a bike is magic & sorcery stuff to me. Personally, I'd be happier paying someone a couple of hundred quid to sort it than screw it up myself !!

Dave - dont worry mate - its not complicated , and not hard - the Guzzidiag tools are simple and well supported and tonnes of guides available here / elsewhere. Not much arder then sending an email really, you just need to get the right cables. If you ahev a basic level with a PC and / or a logical mind, you'll be golden

Dave R wrote:

Right - so tomorrow I'll pull the 30 amps from under the seat & pop the baffle back in & see how how it goes.  

Problem for me is that whilst I can wrap my head around basic mechanics, anything complex scares the life out of me.  And using a laptop to tune a bike is magic & sorcery stuff to me.  Personally, I'd be happier paying someone a couple of hundred quid to sort it than screw it up myself !!

Dave - come over one evening and we can get the laptop out and i can show you :-)

I have sent you a PM

Dave - come over one evening and we can get the laptop out and i can show you :-)

I have sent you a PM[/quote]



Keith - massive thanks for that, got your PM, I'll throw some dates over & see what sticks.  I have the bike booked for a service tomorrow.  Couldn't get it into Twiggers till the end of August, so I'm risking the new, local Guzzi agent.  They're actually a Piaggio dealer who have just been upgraded to a Guzzi dealership.  Normally I'd steer wide clear, on the basis they'd have no idea about Guzzis, but I thought I'd pop in anyway - they're five minutes down the road - nothing ventured, nothing gained.  The lad on the service desk confirmed my initial assumption, but the he called Adam out from the back.  Turns out Adam has been spannering Guzzis for years - from what I can gather, he was running Guzzis mechanic training centre prior to coming here.  Five minutes chat to him gave me a lot more confidence than when I'd first walked in.  

Next stupid question (I have to ask) - if the bike runs better with the baffle in, why are they designed to be removed in the first place ?  Is what I've removed a baffle or a DB killer - or are they same thing ?  My understanding is that baffles are usually fitted by the manufacturer & are perforated, usually with wadding packed between them & the outer wall of the silencer.  Looking down the slip-on, it definitely has a factory fitted, full length baffle.  After doing a bit more reading, what I've taken out looks more like what people call a DB killer (about six inches long, no perforations, held in place by a circlip) which is designed to bring the volume of an illegal (or noisy) system to a more acceptable level.  Is the only reason they can be removed to give your pipes more sound ?  

What am I not understanding ?

Yes it's mainly a 'how noisy do you want to be' thing OR sounding like your going faster when you are actually going slower....... Whilst there are lots of things about baffles & exhaust length influencing gas flow 'dynamics' back to the head that may improve or worsen performance; hopefully we won't start another of those discussions here.....

Dave, it's actually a dB killer. The term 'baffle' and 'dB killer' seem to be interchangeable on these forums. I try not to be too pedantic, or I get called names.

The manufacturers generally refer to the removal of the dB killer as a 'race' configuration. So you can think of it as there for two reasons. One, is for the loud crowd who like a raucous din and a headache while riding, and, two, for those who want to use it on the track and get it remapped for said purpose. Removing the dB killer typically moves the peak power up the rev range.

Of course, it should be remapped regardless. I've seen a lot of comments from people like "I pulled the dB killer and it sounds great and goes much better". This is with an otherwise stock bike. As Paul says, it's all in their heads.

In my experience the baffles affect where the bike makes its power. With them in the bike is more robust in the mid range, with them out the mid feels a little hollow (if that makes sense). I agree with Paul that it really is a question of how loud do you want the bike to be, but in saying that with GRiSO there is a definate performance change.
I always believed that to make a big bore twin sing you had to have open pipes, every Duke I have owned over the years is a testament to that philosophy. Open the pipes and they all felt that they were spinning up better and producing more power, how much of this was wishfull thinking and how much fact I don't know.
What I have learnt since being on this forum is that I may have been mistaken (at least in GRiSO's case), it is not as simple as open pipe = more power! As has been stated here before open pipes tend to work on a race track but underperform on the road, it is why Yamaha developed the exup valve (open at revs, smaller down low).

So me thinking that it's better without the dB killers in is probably me being fooled by the fact that it sounds louder - louder is faster !!!

Getting back to the facts, removing the DB killer, changes the dynamics of the exhaust, therefore the engine tune. A map will fix that, however, having removed said DB killer, will not necessarily give better performance on the road, as the state of tune has changed. Also unwanted attraction from the noise police can also be had, as well as poor fuel consumption, poor performance.

Mark has gone to a lot of trouble to develop maps for real world conditions that match real world exhaust configurations. The 4V/cyl engine is a total different kettle of fish to a 2V/cyl engine and what works on one doesn't necessarily equate to the other (maybe the Ducati reference from a previous post fits in here?).

That's why some run better with a particular exhaust and with the DB killer in. Funnily, once set up and mapped correctly, having "sufficient" torque across the rev range, is far better than having the rush come at 5000 rpm or thereabouts. It just feels tamer, but runs better, and with better economy.

If you want to talk a real open exhaust, talk to Ron (Waterbottle), who has his GRiSO (well one of them) as a track only bike. DB killers be damned, and mapped to suit, with plenty of power up high - this runs on a racetrack, when it's not doing flips in the air (Sorry Ron - couldn't help it - been there myself many years ago, and don't plan to repeat it - it hurts).

So the message here is take take advice from those that have spent the money (I am talking serious amounts of money here) to try different exhausts and develop a map to suit each of them, for real world conditions.

The 8V is not your typical v-twin. The 2V engine responded to such things much better.

To answer your question, it depends on what your definition of performance is. For me, it's best torque that can be made without affecting tractability. On the street. In other words, best torque and power, with a smooth delivery and no rough areas.

For the small number of no-dB killer maps I've made, fuel consumption is marginally higher, but they don't guzzle. It's a moot point, anyway. If you want to use one of my maps, it will have to be with the dB killer in. I didn't make any Agostini maps for use without the dBk.

Hey guys, I expect it has been already said somewhere in these forums, but is there a reason (that does not involve a degree in engineering to comprehend) for the difference in 4v / 2v response to exhaust tuning?

Simples. The 8V has relatively prodigious* valve overlap. Incoming charge transits the combustion chamber and some of it goes straight out the open zorst valve. This is not so much an issue with the 2V. Hence, we like to slow** down the zorst gases on the 8V. Ergo, keep yer dB killer in.






* when compared to the 2V

** if any fuckwit mentions 'back pressure', please fuck off.

Thank you

Leave the killer out only if you run WOT banging off the rev limiter.

No. Don't.

But it's fun, grandad

OK - so I'm hearing dB killer out is BAD, leave it in !!! It's back in now - the bike's down the dealers for a service - mainly for my peace of mind. They're gonna check the shock linkage for ample grease (thanks for that tip Pete), as well as a general look around. Then hopefully meet up with Sidrat for a lesson in mapping

When I purchased mine it had a Termi fitted - no DBK, soon put it back in, it was way to noisy ...
And, when Mark popped one of his maps onboard the first question he asked was "has it got the DBK installed" ....
Stay warm all

I read all these discussions and often think it is all subjective with out any real evidence i.e. dyno charts.

When I was involved in a Triumph Tiger Sport forum a Brazilian guy proved using their peculiar fuel mix his bike got better top end power just by running a open exhaust he backed it up with numerous dyno runs, the evidence was pretty irrefutable.

I have seen little evidence here of people having taken their bikes to a dyno and sharing the results. Don't get me wrong dynos don't tell the whole story but are handy for a before and after comparison.


When I  bought my first CARC Guzzi in 2009 I had it dynoed just for a bit of info to start my data logging project but never went back on the basis of I had the bike running nicely and did not want to change things anymore. Relying instead on the AFR as guide.
Did the bike make more torque or bhp? I haven't a clue but it suited my needs and may have actually been down on power, who knows without the dyno charts to compare back to back.

On my present G1100 using my experienced seat of the pants dyno the bike feels 'harsher' without the db  killer and the extra noise just creates a sense of more power, but in the round the bike is a lot nicer to ride with the db killer in and that's all that matters to me.