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Ducati Monster Forum

Moto Board => Tech => Topic started by: stopintime on October 30, 2008, 01:20:21 PM

Title: One cold, one warm exhaust?
Post by: stopintime on October 30, 2008, 01:20:21 PM
During a cold start (fast idle 2,000 revs) I noticed the exhaust from the upper can was cold while the lower was warm(-ish).
10 minutes later it was still the same difference, although both were a little bit warmer.

Freezing temperature tonight, but the engine behaved perfectly.

I also noticed the exhaust pressure was stronger from the lower/warmer can.

"That's normal" or something I need to have my dealer look into? 
Title: Re: One cold, one warm exhaust?
Post by: EEL on October 30, 2008, 01:30:05 PM
Thats because there's a heat shield on the top can. The bottom doesnt have a shield. Stick your hand under the shied and they'll be the same.
Title: Re: One cold, one warm exhaust?
Post by: stopintime on October 30, 2008, 02:15:48 PM
No, not the can itself - the exhaust coming out of it  [thumbsup]
Title: Re: One cold, one warm exhaust?
Post by: Ducnial on October 30, 2008, 05:58:07 PM
Its the path of least resistance.   Figure the total volumetric flow through the exhaust at an idle is 1/4000 or less at normal engine operating rpms.  At idle rpms the back pressure in the exhaust is nil so the effects aerodynamics within the exhaust pipe, exhaust gas density  even the buoyancy of the exhaust gas can effect flow between cans.

Don't worry about it..
Title: Re: One cold, one warm exhaust?
Post by: Norm on October 31, 2008, 07:31:10 AM
To "feel" the combustion temperatures, touch the exhaust pipe about 6-12" back from the head........be careful. Each cylinder should feel about the same.
Title: Re: One cold, one warm exhaust?
Post by: Ducnial on October 31, 2008, 11:32:18 AM
Quote from: Norm on October 31, 2008, 07:31:10 AM
To "feel" the combustion temperatures, touch the exhaust pipe about 6-12" back from the head........be careful. Each cylinder should feel about the same.

Ouch!  shit that's  F#%&@!$ hot..
Title: Re: One cold, one warm exhaust?
Post by: stopintime on October 31, 2008, 01:47:03 PM
Quote from: Ducnial on October 31, 2008, 11:32:18 AM
Ouch!  shit that's  F#%&@!$ hot..

mine too  [bang]
Title: Re: One cold, one warm exhaust?
Post by: clubhousemotorsports on October 31, 2008, 05:36:45 PM
Now that was some funny stuff ...lol

here hold this spark plug while I try and start the bike ....................... ZAP!!!!


Its almost like he knew you would have to try it. [clap]
Title: Re: One cold, one warm exhaust?
Post by: stopintime on October 31, 2008, 06:32:50 PM
Quote from: ducvet on October 31, 2008, 05:36:45 PM
Now that was some funny stuff ...lol

here hold this spark plug while I try and start the bike ....................... ZAP!!!!


Its almost like he knew you would have to try it. [clap]

I've done that too - to check if I could see the spark - I could at least tell that the voltage was high enough  :o [cheeky]
Title: Re: One cold, one warm exhaust?
Post by: redxblack on November 01, 2008, 04:44:33 PM
that's like telling someone to hold alt and hit f4 to achieve moderator status on a message board/chat room
Title: Re: One cold, one warm exhaust?
Post by: stopintime on November 01, 2008, 05:19:49 PM
Quote from: redxblack on November 01, 2008, 04:44:33 PM
that's like telling someone to hold alt and hit f4 to achieve moderator status on a message board/chat room

Give me just a second........ I'll be back shortly ;)
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