Subject: Lack of power/Discolored muffler Sun Apr 11, 2021 4:32 pm
Hello all! 2015 1200 SE with 3800 miles. Beetle map. Stock muffler.
Started my GRiSO today in 80deg Fahrenheit outside temp. Started easy enough, gunned it a little, it died, it didn't want to start again (turned over, but kinda like a flooded car, not catching). Got it started again, but it was low on power. Rode it around about 10 city miles to see if it would snap out of it. It did not come back to normal power. I started smelling an unfamiliar odor like something getting hot. Pretty sure it was the exhaust/muffler getting hot for some reason. The muffler has turned from its normal brushed silver to a light golden brown (this is scary).
I boogered up one of the plug caps when I did a valve adjust last fall, wrapped it in tape and it seemed alright. Hooked up GuzziDiag today and there are no codes.
Besides telling me to replace the caps (on order), anything else to keep me from damaging my engine? Golden muffler a telltale sign of something in particular?
Subject: Re: Lack of power/Discolored muffler Sun Apr 11, 2021 5:04 pm
Classic sign of the spark earthing to the head/rocker cover. The heat is due to the fuel that isn't burning in the combustion chamber igniting in the catalytic converter, hence the pipe discolouration. Time to swap the plug caps for SB05E or F depending which electrode top you have on your plugs.
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drburt Montanarolo
Posts : 18 Join date : 2020-08-23
Subject: Re: Lack of power/Discolored muffler Sun Apr 11, 2021 7:36 pm
Thanks Pete! I'll report back after replacing plug caps. Need to change the oil in case it got fuel in it? I smelled the dipstick and it just smelled like oil. Anything else to address because of the fuel not burning in the combustion chamber? Thanks!
Pete Roper GRiSO Capo
Posts : 10626 Join date : 2013-05-29 Age : 67
Subject: Re: Lack of power/Discolored muffler Sun Apr 11, 2021 8:05 pm
The biggest risk is that the cat has become clogged/melted. You'll soon notice because it will turn into a horrible, gutless piece of shit. I doubt whether the oil will of suffered in such a short period of running.
drburt Montanarolo
Posts : 18 Join date : 2020-08-23
Subject: Re: Lack of power/Discolored muffler Sat Apr 17, 2021 5:51 pm
Yay! New plug boots and plugs got it running nicely again. It passed the catalytic "horrible, gutless piece of" test today. LOL Is there a more sophisticated way to make sure the exhaust system is fine from a shadetree mechanic's garage? Thanks!
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beetle GRiSO Capo
Posts : 10142 Join date : 2013-09-30
Subject: Re: Lack of power/Discolored muffler Sat Apr 17, 2021 6:06 pm
Not really, unless you forensically examine the cat.
. [You must be registered and logged in to see this image.] . In GRiSO we trust! .
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Gaucho GRiSO Capo
Posts : 17 Join date : 2018-05-02
Subject: Re: Lack of power/Discolored muffler Mon Apr 19, 2021 8:53 am
If you want to get really fancy, you'll need one of this: [You must be registered and logged in to see this image.] It's an exhaust back pressure gauge. You remove the O2 sensor and install it. At idle pressure shouldn't exceed 1 1/4 psi. At 2000 rpm not to exceed 3 psi. If the exhaust didn't get red hot you are probably are fine. The cat will glow with unburned fuel if the situation is extreme. You'll feel a noticeable drop in power when a cat melts. It basically becomes like somebody stuck a potato on your tail pipe. Good excuse to get a slip on. Gaucho
Steak Godfather
Posts : 3154 Join date : 2013-05-28 Age : 59
Subject: Re: Lack of power/Discolored muffler Mon Apr 19, 2021 11:00 am
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2012 MOTO GUZZI GRiSO 1200SE
2013 MOTO GUZZI STELVIO 1200NTX - Orange Blossom Special