free website stats program Interesting observation. | Page 2 | Harley Davidson Forums

Interesting observation.

In order of contriution:

  1. Fuel mixture
  2. Airflow (lowers possibly designed to get air to jugs)
  3. Lubricant (slight, but maybe measureable)
  4. Displacement (slight, but maybe measureable)

Just me guessing...

Enjoy,
Rich P
 
I think one very important reason has been over looked....The age difference will usually mean more or less internal wear. Your '03 may simply be more completely broken in and therefor causing less friction and cooler temps. This is a question I don't think you'll ever get a definitive answer for. JMO
 
In order of contriution:

  1. Fuel mixture
  2. Airflow (lowers possibly designed to get air to jugs)
  3. Lubricant (slight, but maybe measureable)
  4. Displacement (slight, but maybe measureable)

Just me guessing...

Enjoy,
Rich P

Dont forget timing,look at a stage 1 download for an 03 versus a stage 1 for an 08 not only is the timing way different but the AFR difference will astound you! :newsmile082:
 
Here's what I've observed on two recent H-D's with vented lowers and H-D's oil cooler (2010 FLTRX and 2011 FLHTK). Both were 103's with either Stage I (the TK), or II (the RX). Mileage was under 2K on both, and air temps 60-80 F. The bikes were run around 2200 rpm in sixth gear for the test.

Both were lubed per H-D's recommendations with Formula+ in the primary/transmission, and 20W-50 H-D 360 mineral oil in the engine.

The oil pressure (oil viscosity) on these bikes reflects oil temp...the lower the oil pressure the higher the oil temp. I didn't directly measure the sump temp of the oil as I don't care as long as the pressure remains 28-32 psi in cruise. At idle it's around 10-12 psi after a run, plenty for ball or roller bearings.

Operated with the adjustable vents open results in lower oil pressure and more oil cooler cycling. Run with the vents at 2-3 clicks in towards the engine results in the highest oil pressure, and presumably the lowest oil temp. The oil pressure drops again when the vents are full closed at five clicks in.

On both bikes the cycling of the oil cooler valve was obvious. It'd start to open when the oil heated up...just below the middle 32 psi mark. After cooling the oil the pressure would rise 1-2 ticks above 32, stabilize, then the cycle would repeat every few minutes. The Service Manual says the oil cooler valve cycles at around 200 F. I'll take their word on that.

I assume from all this that if the bike's moving at a reasonable speed the lowers may help cool the engine (and oil) if the vents are adjusted properly. I have no idea as to differential cylinder head temps. At slow traffic or idle the lowers may make little difference, and may in fact hinder the cooling due to the relative lack of air flow. Obviously the rider may feel cooler with them removed entirely.

Gary
 
Back
Top