New MPG data

[Gearhead]

Hi,

 

Over the 3 years I've owned my 87 VR 1300, I've averaged 36-37 mpg. While this is right in the mid-range of what a bunch of y'all get, I was always perplexed by the 45 or even 50 mpg-ers. FWIW, I've checked all the usual suspects (fuel levels, new diaphragms, pressure sensor working, new plugs & tuneup, etc). I've experimented with up to four 9/16" holes in the airbox lid which did little to nothing.

 

Then I came across 5bikes (Chuck) and his recommendation to lower the carb metering needles, that it runs rich from the factory in the needle range. Hmmm... Well, after some foolin' around, I arrived at the following:

 

- Needles lowered .050".

- All extra holes in airbox taped over (didn't run well with needles lowered AND holes open).

 

It's running well and for several tanks now I've averaged 40 mpg with the same driving cycle and style I always do. I pulled one spark plug after these few tanks and found that it's very light gray on the ground electrode, light tan on one side of the insulator, the rest of the insulator is white, and just a bit of black on the end of the threaded portion. Seems about right with the detergents in today's gas.

A 10% increase with this adjustment is good, but only half the story. 5bikes gets high 40's on his 1200 but rides almost exclusively country roads and in no hurry either - steady 55-65. I commute to work which is about 1/3 Interstate, the rest mostly suburban / rural roads with a little city. On the Interstate I'm doing 75-90, and other roads I like to accelerate briskly to somewhat over the speed limit (shame, shame). Chuck asked me if I'd run a tank or two slower to see what happens. Thru a supreme effort on my part, I rode the Interstate at 65-70, kept the rural and city roads at or below speed limit and accelerated very gently - for one tank - I couldn't do it any longer :-)

 

The results for that tank? 43 mpg - best I've ever done. So now I'm trying to find a happy medium - a little more spirited so it's more fun, but not as fast as before which will also be better on my driving record. (My current tank, judging by the behavior of the gas gage, will probably end up at 41 or 42.) If I truly ran a tank on just country roads doing 55-65 I'd probably get 45. (It also seems that the 1200's get a little better mpg than 1300's.)

 

I've always heard, and it makes total sense, that driving slower produces better mpg. On one hand I knew my wrist is a wee bit "leaden", but pretty much denied to meself that I was aggresive enough to cause poor mileage. Then I'd read posts here, one says it's all in the wrist, another says their bike gets "40 no matter how they ride". Well, I took numbers, did my best to control the variables, and this is the result.

 

Jeremy

[skydoc_17]

Hey Jeremy,

What a good job on those controlled conditions! Could you please tell me where these "needles" are located you adjusted? I mus have missed the thread by 5bikes, but this sounds very interesting. Did you machine the stock washer .050 thinner or add a different washer? Any information would be very helpful. I too have the 87'VR and would like to increase my mileage and currently run in the mid 30's on my MPG'S.

Thanks for the help,

Earl

[Squeeze]

Earl, the Needles are sitting in the bottom of the Carb Sliders, behind a fairly big plastic Bolt.

Be carefull, there will a Spring, a Piece of Plastic and a Washer come out with the Needle.

 

If you want to lower the Needles, you have to undo these and move the Circlip one Notch UP when holding the Needle at the Tip. IF there are more than one Notch, that is. Not all Needles have adjusting Slots.

[5bikes]

I've done a lot of tuning on dirt bikes, cruisers, tourers and sport bikes. Harley's too!

Basically they are all the same. Lower the needles and screw in the pilot jets the carb runs leaner. Do the opposite to richen the mixture.

The hardest were bikes that sat for a long time and had aftermarket pipes (that always richen, not lean out the air to fuel ratio). Many hours of experimenting and reading.

My 2 Suzuki 1100's 46-52 mpg at 60+ degrees and 65 mph steady cruise. DRZ400 65 city-85 dirt. 1200 Venture 46 avg, 1100 Virago 48+ avg (mostly city).

Look for "Improving Gas Mileage" posts. Averages must be taken over many tank fulls. Consistancy is important in filling up to the same level in the tank, using the same gas pump, holding your throttle hand steady. Cold weather, high speeds, city driving, heavy acceleration, rough roads, inconsistant speeds, different gas pumps, and more reduce gas mileage.

I don't always drive steady now that my 3 tickets are thru the courts but while I was "holding it back" it was another excuse to experiment and get back at the gas companies.

My 2 friends 1st Gen 1300's, now get mid to low 40's but were mid 30's before we retuned them. Send me a PM if you need help.

[Sleeperhawk]

Would this work on a 2nd gen

[Gearhead]

I forgot to give a big "thanks" to 5bikes Chuck for his advice and e-conversation.

 

I just filled up again to the tune of 43 mpg. Remember, this time I was not babying it as much as last tank, but took it somewhat easier than "my old self". I did 65-80 on the Interstate, and accelerated a bit more briskly in general.

 

Skydoc, first do the usual tuneup items. Plugs, maybe valve adjustment, pilot screw adjustment, check float levels, make sure boost sensor (vacuum advance) is functioning. Other than valve adjustment, these are pretty easy. Then, after you do the needle adjustment, pay attention to how it runs. Does it have "lean hesitation"? After a few tanks, pull at least one plug (all of them would be better, and it's best if you start with new ones) and make sure it's not bone white.

 

That being said, the needles are not adjustable per se. They have white plastic spacer washers holding them up in the slides. The thickness of the washers is .100", but they sit up on a nib and counting the nib they are more like .120" (I think, don't have the numbers in front of me). I removed these washers and found a variety of washers with similar ID and similar or smaller OD to stack and obtain various thicknesses. I had to raid a couple hardware stores with calipers in hand, and also snagged a few from some open stock where I work, to get a sufficient variety of thicknesses. First I lowered them .030, so I stacked washers about .090 thick. I then went down another .020, so the washer stacks in there now are .070 thick. I verified the height change by measuring the needle protrusion thru from the slides before and after modification.

 

When I started, I had holes in the airbox lid. With the needles down .030 I might have noticed slight lean symptoms and a small increase in mileage. With them down .050 the mileage was about the same but the lean symptoms were undeniable at that point. I taped over the holes and, viola, the mileage went up 2 or 3 points and the lean symptoms went away! So the airbox is now stock except for two things which didn't affect the way the bike runs: K&N element installed, and I noticed that the top "ceiling" of this element sits a little lower than stock, so I cut about 1/4" off the top of the square "stack" in the center of the element. There was no discernable effect.

 

Jeremy

[timgray]

Does anyone know if the procedure is different for an 83? I know the 83 is a wierd animal in some aspects compared to the other 1st gens. I just might have to do this this spring at the end of my reassembly and tune up. I've been getting 32 on a good day, and 27 when I make kids on Ninjas cry.

[CrazyHorse]

Earl, the Needles are sitting in the bottom of the Carb Sliders, behind a fairly big plastic Bolt.

Be carefull, there will a Spring, a Piece of Plastic and a Washer come out with the Needle.

 

If you want to lower the Needles, you have to undo these and move the Circlip one Notch UP when holding the Needle at the Tip. IF there are more than one Notch, that is. Not all Needles have adjusting Slots.

 

 

86-93 do not have notches at least my 1990 does not I used tiny washers and removed the plastic ring and I get about the same as Gearhead with the 1990 needles. I also have a set of 1984 needels and they have alot more taper to them then the 90 does and 5 settings. I used the 84 needles set at the most out setting and had great power mileage went down 25mpg with heavy throttle, though when the weather gets better Im going to lower them to the lowest setting and see what I get. I have a hard time riding 55. If I did what my speedo said I was doing I would be doing about 47-48 mph mines off so then I could see 50 mpg.

Edited January 30, 2009 by CrazyHorse

[Rottdoglover]

Does anyone know if the procedure is different for an 83? I know the 83 is a wierd animal in some aspects compared to the other 1st gens. I just might have to do this this spring at the end of my reassembly and tune up. I've been getting 32 on a good day, and 27 when I make kids on Ninjas cry.

27 MPG is a small price to pay to watch Ninja Kids cry. I bet you could still outrun 'em with the carb mods & get better mpg

[5bikes]

If it is carbureated, has needles, with and without slides (plastic or metal), lowering the needles will lean them out and you will get better gas mileage. Opposite is sometimes true. In my opinion a leaner mixture is a hotter mixture therefore more power. (Up to too lean) Also is a cleaner mixture.

But as Gearhead (Jeremy) said make sure it is tuned up first, everything else is working correctly first.

I've done this on at least 10 bikes. It works. My 102k mile Suzuki runs better now than it did when I bought it 15 years ago. Gets 50 mpg and is very throttle responsive. Venture is also.

Hesitation under 2k rpm is pilot screws (the ones under the cap) Hesitation above 2.5k rpm is more likely needles. No power over 5k is usually too rich mixture.

Do not mess with changing the jets.

Check spark plugs often after doing any changes. Even newer formulated gasoline will cause plugs to be black if the mixture is too rich, white if too lean. Gray, tan or clean is about right. This is only a 1-2 hour job the first time, 1/2 hour the next.

[jasonm.]

5bikes , good info. Don't forget sluggish above 5k is sometime bad slide diaphragms. Wish I had a GSX1100G ...I luv those torque monsters. Modern engines like an ~ 13:1 fuel air ratio for most power. But will run @14:1 . Too lean always reduces power with hesitation. Too rich reduces power as the engine gets hotter but usually runs without hesitation symptoms. My experience >Too rich takes longer to figure out and resolve to perfection.

Edited January 31, 2009 by jasonm.

[Squeeze]

But too lean will make big Holes in small Pistons.