i have been building exhausts for the older type guzzis for a while now. this is my first attempt at an injected guzzi.i find the standard muffler ugly and restrictive so this is what i came up with... this has no restriction inside both outlets are 49mm inside. has perforated tube and packed with fiberglass wool. seems to idle fine add rev i have not been for a test ride yet.... i am new to the GRiSO i have only had it a few weeks.
who is the wizard at tuning Grisos if i have dramas i am in central Queensland??
Pete Roper GRiSO Capo
Posts : 10704 Join date : 2013-05-29 Age : 67
Subject: Re: custom Muffler Sat Jul 01, 2017 6:39 pm
I think I may of said elsewhere that it looks like the Lavizzari system I had on my 1100.
As has been stated ad nauseam a totally open pipe is actually counter productive with the 8V motor due to charge transition issues. It may get you a couple of extra HP at the top end but it will damage and hinder cylinder fill and consequent torque at other places in the rev range and throttle opening.
As for mapping help? Ask Mark. But you will need Guzzidiag and 'Reader' and 'writer' to tune and upload/download maps.
Pete
beetle GRiSO Capo
Posts : 10198 Join date : 2013-09-30
Subject: Re: custom Muffler Sat Jul 01, 2017 6:56 pm
The good news is that you've kept the pretzel. That plus the union of the double muffler will help slow the exhaust down. To keep the bottom and mid torque curve healthy, I would recommend a bit more advance in the ignition map if you don't wish to add reducers in the outlet ports.
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Ratty GRiSO Capo
Posts : 14 Join date : 2017-05-31 Age : 43
Subject: Re: custom Muffler Sun Jul 02, 2017 12:21 am
Went for a ride runs fine, i am surprised at how well it goes after reading comments on here.possibility has less bottom end power. would need to dyno to check. does backfire on engine brakes sometimes,but it did with standard muffler.
i dont know what map its running. has standard headers & mid pipe. and air box looks untouched. i got it from a dealer with 11,000kms on it.
chergo Squinternotto
Posts : 1 Join date : 2021-08-02
Subject: Re: custom Muffler Mon Oct 04, 2021 11:55 am
has anyone removed the stock 8V muffler endcap and drilled out the metal blocking visible in each of the exhaust tubes?
Pete Roper GRiSO Capo
Posts : 10704 Join date : 2013-05-29 Age : 67
Subject: Re: custom Muffler Mon Oct 04, 2021 4:28 pm
Why would you want to do that?
Bill Dee Tanabuso
Posts : 82 Join date : 2020-08-26
Subject: Re: custom Muffler Sun Oct 24, 2021 9:17 pm
Folks believe the muffler will flow better if that is drilled out. Will it ??
I had the cat element removed by a welder. Can't tell any difference.
Pete Roper GRiSO Capo
Posts : 10704 Join date : 2013-05-29 Age : 67
Subject: Re: custom Muffler Sun Oct 24, 2021 9:41 pm
It's performance will not be improved by 'Drilling anything out' or removing the Catalyser.
lcjohnny GRiSO Capo
Posts : 1470 Join date : 2016-01-25 Age : 69
Subject: Re: custom Muffler Mon Oct 25, 2021 4:25 am
It is strange how this myth of "back pressure" and the need to reduce it still hangs around Assuming you have not got an exhaust header like a lawn mower there will be some lengthy large and gently curving tubes - not a resistance to flow from the cylinder head.
Unless "back pressure" means pressure waves ? If it does then as pressure waves coming back up the tubes are negative and positive "reducing" their amplitude would reduce the power of any IC engine that i have heard of.
Drilling holes in a pipe may make more noise - if that is what you want then go ahead
beetle GRiSO Capo
Posts : 10198 Join date : 2013-09-30
Subject: Re: custom Muffler Mon Oct 25, 2021 1:50 pm
Subject: custom Muffler 
Sat Jul 01, 2017 6:15 pm
