The exhaust coming from the left pipe (rear cylinder) is much cooler than the exhaust coming from the right side on my 2004 Ultra. So, is that normal?

mike

 

Unless you have true duals on your bike you get very little exhaust from the left pipe, Yes that's normal..

 

Usually the rear cylinder runs warmer than the front or so I have read...

 

Yep, forgot about exhaust types....

 

less of an issue with modern EFI, fuel delivery to the cylinders is independent of each other.

on the old bikes, you'd tune the carb to the rear cylinder, leaving the front a little rich. or fiddle with sparkplugs

mike

 

At idle I get a lot less flow out the left pipe.
It is a 60/40 system and I have no explanation for it. Would like to hear the explanation from a Harley engineer. Or anyone.

 

Normal, my left muffler never gets too hot that I can't lay my hand on it......stock header on a 08 Ultra, with 4" Jackpot mufflers.

 

I also believed the rear cylinder runs hotter than the front as it does not have very good air flow, and what air flow it gets is most warm air passing by the front cylinder. I also have a 2004 Roadstar 1700cc, and that back cylinder runs much leaner than the front, but both pipes are equally hot (you cant lay your hand on either one)

I just changed pipes and thought something was not right..

thanks for the replies

mike

 

The rear does run hotter, but you might be surprised to find out how much, or rather how little. I have the ability to see the front and rear CHTs and my bike has an individual cylinder tune that is well balanced. My observations show that the majority of time the engine is running, the rear is 0-15 degrees hotter, max difference is 30 degrees only after about 20-30 of highway speed operation in the 3k+ RPM range, also at speeds below about 45 MPH and idle the front and rear CHTs tend to equalize.
Your factory pipes, by design routes most of the exhaust to the right side so it stands to reason that the left is a little cooler. Why are they built that way? Best guess is to get some of the performance benefit of scavenging while maintaining the widely desireable symetrical appearance.

 

Thanks fabrik8r

I think you nailed it. I was just in awe of how much difference there was in temperature between the two pipes in a completely cold engine. Like I stated I had just changed mufflers and had not noticed this until now....

Thanks for the explanation...

mike