A new question on aftermarket exhaust

Started by Tfrank59, September 22, 2015, 07:59:03 AM

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Tfrank59

#5

I can't increase back pressure anymore than it already is, the thing's already half constipated :P

No wait, since I pulled the baffles out and saw that the shorter pipe was running hotter, I actually put some muffler packing in there (which is why I pulled out the baffles), so now it has more back pressure than it had, if that makes sense.  But I hate to stuff anything more in there because it really is a bit constipated now. ;D

Tom

'06 Drifter 800, '98 Valkyrie

"HD: The most efficient way to convert gasoline into noise without the pesky effects of horsepower."

Troll

no, not better...LEANER, which makes the exhaust HOTTER...That's why you need to increase back pressure a little so it doesn't OVER SCAVENGE....

Recovering H-D owner...W-650 Cafe' No excuses...Ride it or sell it to someone who will!

Tfrank59

Huh, so you're saying the short pipe (rear cylinder) is actually running better?  I didn't really ever consider that hotter could be better. ???

Tom

'06 Drifter 800, '98 Valkyrie

"HD: The most efficient way to convert gasoline into noise without the pesky effects of horsepower."

Troll

Quote from: Tfrank59 on September 22, 2015, 07:59:03 AM

So all you guys out there that want straight pipes instead of the stock exhaust – man I wish I could trade with you!  I've been trying to get my shotgun exhaust tuned, and of course there's a short and long pipe (short pipe, rear cylinder), and the short is running hotter than the long pipe.  You gurus that know all about this stuff, is this something I need to worry about?  Is that actually normal? – I'm thinking yes.  The only way I could tell was when I pulled the baffles out, I saw where the short pipe's baffle had been getting hotter than the long pipe's.  I also know that the age-old problem with V twins is that the rear cylinder runs hotter because it doesn't get as much airflow – but this is a liquid cooled motor.

In this case, it's airflow, but not cooling airflow, but rather exhaust scavenging. More back pressure in the short pipe will improve the mixture and balance the airflow. This is why I always preferred a collector system

Recovering H-D owner...W-650 Cafe' No excuses...Ride it or sell it to someone who will!

Tfrank59

So all you guys out there that want straight pipes instead of the stock exhaust – man I wish I could trade with you!  I've been trying to get my shotgun exhaust tuned, and of course there's a short and long pipe (short pipe, rear cylinder), and the short is running hotter than the long pipe.  You gurus that know all about this stuff, is this something I need to worry about?  Is that actually normal? – I'm thinking yes.  The only way I could tell was when I pulled the baffles out, I saw where the short pipe's baffle had been getting hotter than the long pipe's.  I also know that the age-old problem with V twins is that the rear cylinder runs hotter because it doesn't get as much airflow – but this is a liquid cooled motor.

Tom

'06 Drifter 800, '98 Valkyrie

"HD: The most efficient way to convert gasoline into noise without the pesky effects of horsepower."

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