Harley Rear Cylinder temps

[Galo]

FYI.....yesterday, when I was picking up my steed from getting a new chain & sprockets, I picked up a plain paper rag (dont ask me which, okay??) that had an article about the '06 and newer Harleys and how, with the new EPA regs that went into effect in '06, rear cylinder temps are approaching and exceeding 400 degrees.

In fact, there was mention of a documented case where two identical Road Kings, one an '04 and another an '07 ran together for an hour and pyrometers were placed in both bikes cylinder heads right alongside the spark plugs, and the '04 bike registered 260 degrees on the front cylinder and 310 on the rear cylinder while the '07 registered 280 degrees on the front cylinder and 460 degrees on the rear cylinder!!

 

The article goes on to say that it appears that the much leaner mixtures required to pass '06 regulations are the cause of these much higher cylinder head temps, and it recommends that newer Harley owners find FI remapping experts/other means to enrichen their mixtures...

Please do your homework...you have been advised...

[scott-sts]

I have no doubt this is true but keep in mind, the japanese have also leaned their mixtures to pass emissions.  This has been going on for years.

[chornbe]

Yep, and yep.

Yep, the rear cylinder on the Harleys run hotter because they run very, very lean (partially because of their stupid single-pin crank and firing order, the rear cylinder is often in a state of misfire at idle, demanding a leaner mixture to pas regs). There is (FINALLY!!!) talk of either going to a dual-pin crank, modding the firing order, or (FINALLY!!!) going to the Revolution engine on the touring bikes.

Cro-Magnons everywhere are up in arms.

I've said it before... Slap that Revo in a 'Glide and I've have bought one years ago!!

[DCLXVI]

You can have the FI re-mapped at the dealer for free. What it will do is shut off fuel to the rear cylinder at idle to cool the cylinder temp. As soon as it goes of idle it starts up again. Should be almost seamless. Good Luck

[vitaminC]

Do HD's come equipped with catalytic converters?

[st ryder]

FYI.....yesterday, when I was picking up my steed from getting a new chain & sprockets, I picked up a plain paper rag (dont ask me which, okay??) that had an article about the '06 and newer Harleys and how, with the new EPA regs that went into effect in '06, rear cylinder temps are approaching and exceeding 400 degrees.

In fact, there was mention of a documented case where two identical Road Kings, one an '04 and another an '07 ran together for an hour and pyrometers were placed in both bikes cylinder heads right alongside the spark plugs, and the '04 bike registered 260 degrees on the front cylinder and 310 on the rear cylinder while the '07 registered 280 degrees on the front cylinder and 460 degrees on the rear cylinder!!

 

The article goes on to say that it appears that the much leaner mixtures required to pass '06 regulations are the cause of these much higher cylinder head temps, and it recommends that newer Harley owners find FI remapping experts/other means to enrichen their mixtures...

Please do your homework...you have been advised...

The newer bike is also a TC96, not a TC88, which has a bigger bore, (or is that a longer stroke?)  but not more proportional cooling fin area. It will always run hotter regardless of any reflash.  

[st ryder]

Do HD's come equipped with catalytic converters?

Not the air cooled BTs or Sportys.

[vitaminC]

Not the air cooled BTs or Sportys.

Seems like that would be an easy way to meet the emission regs while minimizing excessive cylinder heat  

[chornbe]

Yes and no... too much unburned fuel can toast a converter pretty quickly, and the rear cylinder is often misfiring at idle. It would make more sense to FIX THE INHERENT ENGINE DESIGN FLAWS in the single-pin crank engine with the fucked up firing order.  

[Galo]

Yep, and yep.

Yep, the rear cylinder on the Harleys run hotter because they run very, very lean (partially because of their stupid single-pin crank and firing order, the rear cylinder is often in a state of misfire at idle, demanding a leaner mixture to pas regs).

That's it exactly, Chris.....that paragraph/fact was in the same article as well.....
Cro-Magnons up in arms....LOL!!!!!!!!