My 2003 Ultra Classic is on its second oil change with Royal Purple MAX-Cycle 20W50. I live in Southeastern Oklahoma and our summer temperatures have been running at or near the 100 degree mark for the month of July and August.

During this time I have been riding my Ultra, the gauge has always indicated an oil pressure at idle.

I recently took a trip to Colorado Denver area September 13th thru September 18th during which the weather temperature there was in the low 80 degrees during the day but the engine oil pressure was 0 at idle and the engine idle dropped to 500 RPM's.

Any ideas as to what cause this change? Can altitude affect oil viscosity or pressure and what's up with the RPM drop at idle?

Other than the oil pressure and idle change the bike ran fine.

 

you may had reached the temp where the bike goes into the heat management mode to prevent overheating. at that point the bike only fires every other time or half as much. If it does not do it in normal riding that is probably what happened. high temps thinning out the oil and going into the heat protection mode could cause the condition you describe. Again, does it do it in normal riding. altitude changes should not have a dramatic affect although thinner air does cause the bike to run hotter but the injection system should compensate for that. were you idling heavily in traffic ? thats usually what happens.if this condition happens frequently have it checked out.

 

Thanks for the input MACK. The conditions that I described did not happen in stop and go heavy traffic. It happened the first time I exited from Interstate 25 in Denver. Stopped at the first red light I encountered after my last fuel fill up and approximately 150 mile nonstop riding.

As I mentioned, I had just left my home town area where I had been riding in near 100 degree weather and none of these conditions occurred.

The only three differences are the non-stop distance traveled, fuel octane lower and altitude change. Most of the trip was at 60 to 65 MPH.

 

Dane,

I had this happening to me earlier this spring. As it turned out for me it wasn't the overheat mode, but too rich a mixture at idle. I pulled the numbers down 4 all through the 0% throttle setting on the PC III and hasn't happened since. Could you be going into a rich situation at the higher altitude? -- Tom

PS --- Dane, how's the backrest holding up?

 

Hey Tom,
The backrest is doing great, especially on my Golden Colorado trip, Thanks.

You may be very well right about the lean fuel condition. I don't know anything about the PC III system. Someone will have to educate me about that. Generally I'm reluctant to add many after market things unless I know for sure it's worth the buy.

Another piece of evidence the Ultra may be running lean. I posted this on another thread but I post it again.

On my return trip from Colorado climbing a not so steep hill South on I-25 at Raton Pass, I was doing all the Ultra would do in high gear at 65 MPH when A late model Goldwing pulling a trailer also with a passenger slowed to wave as he passed me in high gear with little or no effort.

I'm pretty heavy at 280 lbs and riding solo but the Goldwing rider was 250 plus, the passenger was at least 200 lbs, and then there was their trailer. There's no telling how much weight the Wing was pulling.

How I know they were in high gear was that I caught up with them at a rest stop down the road. I ask if he was in 4th or 5th gear when he slowed to wave at me and he said the Goldwing was in high gear. I kind of thought he was in high gear but I wanted to confirm my suspicion. Having had ridden Goldwings for 29 years I know what they sound like in all of the gears even though they are quiet as they are.