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Big windshield's MPG cost


Sailorlite

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Sailorlite

Trip 1 (SoCal looping through No. Nevada, March 2010): 1,600 miles, Cal Sci medium windshield, 42.8 MPG.

Trip 2 (SoCal looping through So. Oregon, May 2010): 2,600 miles, stock windshield, 49.4 MPG.

 

Both trips were on my '08 RT 1-up, with similar luggage, similar weather, MIchelin PR2's w. similar pressures, similar state of engine tune. (I did have the 28L topcase mounted for the May ride). I used the trip odometer and gas station receipts for the mileage calculations.

 

My conclusion is that the entire difference in MPG is due to the difference in windshields - a much greater difference than I would have expected. I ride with a full face helmet and custom earplugs (comfortable) so noise or "buffeting" reduction are not very important or even very noticeable to me. I calculate that the "cost" of the Cal Sci is roughly $9 per 1,000 miles - not so much compared to everything else, but, for what?

 

After Trip 1 I thought I'd reinstall the Cal Sci next winter when its protective aspects would be more useful. But now I think I've experimented enough, and the Cal Sci will remain in reserve. (And I'd expect other larger windshields to yield similar results).

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Paul Mihalka

Correct. Way back in 1986 three of us took a trip from Miami area to Atlanta and back. All on Interstate, riding together. One guy short, on a K100RT with the original aerodynamic Euro windshield, other guy 6ft+ tall on a K100RT with a tall after-market windshield, I on my K75 with a Hannigan fairing. I got the best mileage, but between the two K100RT the difference was a consistent 5 mpg at every fill-up.

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Hmmmm,

I know that on my GT I get better mpg average when I have my topcase on the bike.

I always have bags, w/big touring lids, so that is canstant.

2 up I get my best mpgs due to type of riding, but topcase is always on then too.

After a trip I left the topcase on, don't usually.

REsult?

Higher mpg average than w/out it.

I think on my bike it has a positive effect on slipstream/aero drag.

Maybe the 28L helped you too.

Try riding a tank w/&w/out it just to see.

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1LIFE2LIVE
Trip 1 (SoCal looping through No. Nevada, March 2010): 1,600 miles, Cal Sci medium windshield, 42.8 MPG.

Trip 2 (SoCal looping through So. Oregon, May 2010): 2,600 miles, stock windshield, 49.4 MPG.

 

Both trips were on my '08 RT 1-up, with similar luggage, similar weather, MIchelin PR2's w. similar pressures, similar state of engine tune. (I did have the 28L topcase mounted for the May ride). I used the trip odometer and gas station receipts for the mileage calculations.

 

My conclusion is that the entire difference in MPG is due to the difference in windshields - a much greater difference than I would have expected. I ride with a full face helmet and custom earplugs (comfortable) so noise or "buffeting" reduction are not very important or even very noticeable to me. I calculate that the "cost" of the Cal Sci is roughly $9 per 1,000 miles - not so much compared to everything else, but, for what?

 

After Trip 1 I thought I'd reinstall the Cal Sci next winter when its protective aspects would be more useful. But now I think I've experimented enough, and the Cal Sci will remain in reserve. (And I'd expect other larger windshields to yield similar results).

 

I've had a large Calsci screen on for the last couple thousand miles and noticed a similar loss in mileage. The extra protection here in Michigan is much appreciated especially during the colder months and the vent on the Calsci does work in reducing back pressure and buffeting.

 

Having said that, yesterday I reinstalled the OEM screen since its getting into the 80's again and will keep it on until the fall for the added wind flow.

 

I have thought of cutting a vent in the OEM screen to replicate the Calsci.

 

Has anyone done this?

 

THANKS,

08RT

 

 

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I dropped 2 MPG when I bought the Meyer Day Long saddle. I had them add 1.5" in height. Little bit made a big difference.

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I don't get it! I have a Calsci Ex Large and have not noticed any degradation in MPG (and I am constantly traveling at high speed). If you didn't have the screen than the wind would be hitting your body which is far less aerodynamic than a nice slippery screen!

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I find about a 10% fuel penalty when using the CalSci, but in cold weather, that is a small price to pay for superior protection. YMMV

 

As far as vents, I cut off the bottom of the stock screen and added a vent (using the CalSci as a template) and it really works GREAT. I used masking tape & packing tape (liberally) to avoid scratches on the screen and to mark the layout lines. I used a scroll/saber saw with a very fine tooth, small blade and took my time...great results.

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Hank in WV
I went to a larger key fob and lost 8 miles per gallon....anyone riding without a fob?

 

 

What brand of fob are you using? I find the BMW Fobs too costly and prone to early failure.

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1LIFE2LIVE
This should give you an idea of the stocker mod a la CalSci:

 

862748306_EqAE5-L.jpg

 

Thanks for your testimony and this photo!

 

I just finished doing this mod. to my 08RT OEM screen - no cutting/trimming problems.

 

We'll be giving this shield a test run with a relatively long distant ride this Memorial Day Weekend (about 850 miles roundtrip).

 

My Large CalSci screen has proven to be Very effective in reducing back pressure and buffeting. Now with this OEM Cal Sci a fied screen we should be good to go for both the hotter and colder riding conditions.

 

Ride report and photo to follow.

 

Ride Safe & Often as Possible,

 

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I don't get it! I have a Calsci Ex Large and have not noticed any degradation in MPG (and I am constantly traveling at high speed). If you didn't have the screen than the wind would be hitting your body which is far less aerodynamic than a nice slippery screen!

 

+1 Me too.

 

Switched to CalSci. "Medium" shield (somewhat wider then oem & about 1/2" taller) with good (slightly better miles per gallon, less buffeting, improved air movement behind the screen) results.

 

Next, the day before leaving on a short trip, removed previously added GS mirrors and installed a Booster Plug (#3 on list of alternatives shown). The trip was about 1,150 miles over two days and included a combination of high-speed freeway travel, Arkansas mountain twisties & lowland back road fun.

 

Too many variables to draw specific conclusions but by itself, the addition of the CalSci windscreen did not hurt gas milage & in my case, increased it slightly.

 

Even considering the other stuff done afterward (and not forgetting a tank of ethanol-free gas along the way) I enjoyed (for me) better overall milage per tank, ranging from a low of 43.5 to one fillup @ 47+. Past trips like this ranged between 38 -42+ mpg.

 

Like I said, too many variables (for ex., adding a Booster Plug supposedly can decrease mpg by a few percentage points) to really make a case for anything specific but overall, I'm hoping this combination will hold up long-term as regards milage & air flow.

 

Time will tell; now if I could only find a way to get more then 5K miles out of a rear Avon Storm! :/

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It's just become warm enough for me to go ahead and mount my new CalSci large screen. Took it for a test ride and promptly switched back to the OEM screen. The CalSci howls at any highway speeds and doesn't provide enough noticeable difference for it to be worth all that noise. For me anyways. I think that I will just stick with the stock screen.

Now I have to see if CalSci will take this back. Sigh.

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1LIFE2LIVE
This should give you an idea of the stocker mod a la CalSci:

 

862748306_EqAE5-L.jpg

 

Thanks for your testimony and this photo!

 

I just finished doing this mod. to my 08RT OEM screen - no cutting/trimming problems.

 

We'll be giving this shield a test run with a relatively long distant ride this Memorial Day Weekend (about 850 miles roundtrip).

 

My Large CalSci screen has proven to be Very effective in reducing back pressure and buffeting. Now with this OEM Cal Sci a fied screen we should be good to go for both the hotter and colder riding conditions.

 

Ride report and photo to follow.

 

Ride Safe & Often as Possible,

 

Last night I went for a quick spin (about 70 miles) to test my new OEM CalSci a fied screen through some twisty and high speed interstate conditions and have to say that this mod for me (6' 32" inseam) with a Russell Day Long in the low position is FREAKIN PERFECT!

 

No buffeting, back pressure, NOTHING = NICE!

 

Thanks again Byron for posting your impressions and photo!

 

 

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Hi John,

 

Welcome to the Board!

 

I have (currently :/ ) a medium CalSci mounted: went and looked; seems like the bottom cut is within 1/4" of the black brackets.

 

If the hole measurements don't show up pm me & I'll go trace a template.

 

 

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1LIFE2LIVE
This should give you an idea of the stocker mod a la CalSci:

 

862748306_EqAE5-L.jpg

 

Thanks for your testimony and this photo!

 

I just finished doing this mod. to my 08RT OEM screen - no cutting/trimming problems.

 

We'll be giving this shield a test run with a relatively long distant ride this Memorial Day Weekend (about 850 miles roundtrip).

 

My Large CalSci screen has proven to be Very effective in reducing back pressure and buffeting. Now with this OEM Cal Sci a fied screen we should be good to go for both the hotter and colder riding conditions.

 

Ride report and photo to follow.

 

Ride Safe & Often as Possible,

 

Last night I went for a quick spin (about 70 miles) to test my new OEM CalSci a fied screen through some twisty and high speed interstate conditions and have to say that this mod for me (6' 32" inseam) with a Russell Day Long in the low position is FREAKIN PERFECT!

 

No buffeting, back pressure, NOTHING = NICE!

 

Thanks again Byron for posting your impressions and photo!

 

 

Well after riding over 900 miles this past Memorial Day Weekend end Two-Up I'd/We've got to say that this OEM CalSci a fied screen (tried to upload some pictures and was unable) is the BOMB!

 

She (5'6") repeatedly mentioned how much "smoother" and comfortable she felt during our entire adventure (Metro Detroit to Traverse City, Northport, Suttons Bay, Leelanau, Leland, Glen Arbor & Ludington). Get the chance ride M-22 it's Awesome!

 

Happy Bikers R US,

Silver 08RT

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  • 5 months later...

I see one of your trips was in March and the other in May. The first thing that occurred to me is the fuel mix in your area may be "adjusted" to meet regional air quality targets.

 

I'm in upstate NY and back in the mid 90s saw my very consistent 32 mpg car mileage drop to 24 mpg in November. About that time there were some local news articles about additives to the gas to help the region meet air quality standards. There was some reasoning on why they did it in the winter, vs. all year long.

 

By May my mileage would return to the 32 MPG and run that way until the first tankfull of November. And so the cycle went. The only reprieve was when I drove to some southern states and saw some hit or miss bumps in MPG.

 

Just an alternative to think about.

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Based on my experience, I'd argue that headwinds and ambient temp (more throttle to produce a given HP at high temps cause less pumping losses and greater fuel economy) cause a greater fuel economy variation than aero.

 

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