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Royal Enfield Motorcycles => Bullet with the UCE engine => Topic started by: emskee on October 20, 2009, 05:09:26 pm

Title: MPG versus temperature for a C5 question
Post by: emskee on October 20, 2009, 05:09:26 pm
Fine People,

I have a C5.

I'm losing MPG and wonder if the temperature is a factor.

I have a 33 mile drive each way to work.

156      to 448.8 miles 70.00 mpg  no freeway, 90 minute ride each way
448.8   to 595.5          70.26 mpg  ditto
595.5   to 732.9          74.11 mpg  ditto
732.9   to 897.7          74.80 mpg  ditto
897.7   to 1022.8        78.71 mpg  ditto
1022.8 to 1169.4        79.41 mpg  ditto
1169.4 to 1304.9        73.56 mpg  freeway, morning temps 50s, afternoon 60-70s
1304.9 to 1456.7        70.16 mpg  freeway, morning temps 40s, afternoon 50-60s
1456.7 to 1606.7        63.70 mpg  freeway, morning temps 30s, afternoon 40-50s

Anyone see similar results?  I will also query my dealer but wonder what the group has experienced.

Thanks,

Mike
Title: Re: MPG versus temperature for a C5 question
Post by: ace.cafe on October 20, 2009, 05:42:12 pm
In colder weather, the air is denser.
The ECU regulates the fuel mixture to meet the increased air mass, to maintain proper fuel ratio.

Those of us with carburetors need to richen our jetting or mixture settings in cold weather for the same reasons.

Also, some locations may already be switching to winter-formulations of gasoline, with more ethanol, which will knock about 10% off your fuel economy right there.
Title: Re: MPG versus temperature for a C5 question
Post by: emskee on October 20, 2009, 07:44:50 pm
Ace.cafe,

Thanks, but 20%!?!?

I mean, this is my third fuel injected bike and I ride all year long, which means I took/take my bikes out in single digit weather when the roads are no worse than wet.  Also, I've had two carbureted bikes and sure, an air mixture tweak, maybe a jet jet change twice a year.

I'll say this, the two fuel injected bikes I had before this went from 36 summer to 34 in the winter and 46 summer to 43 in the winter.  The carbureted Harley never skipped a beat with about 50 mpg always.  I can say the same for my Ural Gear Up which gets 38-40 no matter what is going on to include the jet and mixture tweaks and trips to work at 8 degrees and at 80 degrees.

Just don't seem right.....

Mike

Title: Re: MPG versus temperature for a C5 question
Post by: ace.cafe on October 20, 2009, 09:21:28 pm
Well, I guess it's best to check with the dealer then.
Perhaps one of the sensors that provide input to the ECU has been affected by something.
Title: Re: MPG versus temperature for a C5 question
Post by: The Garbone on October 20, 2009, 10:41:52 pm
Quote from: emskee on October 20, 2009, 07:44:50 pm
Ace.cafe,

Thanks, but 20%!?!?

I mean, this is my third fuel injected bike and I ride all year long, which means I took/take my bikes out in single digit weather when the roads are no worse than wet.  Also, I've had two carbureted bikes and sure, an air mixture tweak, maybe a jet jet change twice a year.

I'll say this, the two fuel injected bikes I had before this went from 36 summer to 34 in the winter and 46 summer to 43 in the winter.  The carbureted Harley never skipped a beat with about 50 mpg always.  I can say the same for my Ural Gear Up which gets 38-40 no matter what is going on to include the jet and mixture tweaks and trips to work at 8 degrees and at 80 degrees.

Just don't seem right.....

Mike



Well,  I think displacement also is telling in the effect temp has on the mpg.   I imagine the bigger bikes see less effect.  

A buddy of mine has a powerstroke diesel.  He gets 15mpg empty or or 15mpg pulling a 20ft trailer.      Changes in temp/ air density probably can be thought of the same way,   The V-twin and opposing twins just chug along because they are operating well inside their performance envelope,  but the relatively low power single  breathing in large gulps of the stuff has a tougher time since it is closer to the edge of its performance envelope to start with..

Just my opinion,  your mileage may vary...   ;D
Title: Re: MPG versus temperature for a C5 question
Post by: PhilJ on October 21, 2009, 12:19:36 pm
According to your chart at the time you started loosing mileage you started using the freeway.
I'll bet you're riding faster = less mileage.
Title: Re: MPG versus temperature for a C5 question
Post by: emskee on October 21, 2009, 02:19:47 pm
Dig it.

But my original question stands:  What are you other guys seeing now that the weather is colder and, I will add, when you are doing highway riding?  For that matter, when the weather is/was warm, what do/did you highway riders see?

Thanks,

Mike
Title: Re: MPG versus temperature for a C5 question
Post by: PhilJ on October 21, 2009, 04:14:05 pm
Mine is not a C5 or G5, it's an AVL. Last winter I didn't really notice any real difference from summer riding. We have now gone from 100* + to 60s to upper 70s, still no significant difference. My last fillup yesterday was 85 mpg probably averaging 40 ~ 45 w/ some top speeds hitting 55-60 mph.