FJ is running great, but my MPG has been crappy.

[E Double]

Ok folks,

As you know I have an '84 FJ1100.  74K miles, runs like a top.  But lately my gas mileage has been rubbish.  Typically I get between 36 and 38 MPG, but recently (the last three tanks of gas) I've been around 32, 33mpg.  No difference in riding style, terrain, or anything else.  The bike has a Vance and Hines Supersport exhaust with a stage two jet kit, stock airbox. MY gearing is 18/39 if it helps. I changed the plugs and filter approximately 8K miles ago, when I did a valve adjustment.  I'm kinda stumped as to what I should do.  I figured I'm about do for a new air filter, and was thinking about going to pods, but If I do so will I have to rejet the carbs, and if so will it make my gas mileage even worse?  I frequently ride to work instead of taking my truck and I'd like to get the best mileage possible.  I certainly don't need any more oomph than my bike already has, especially if it means a hit in my mileage.  Any suggestions?  Cheers in advance for any help!

Dennis

[craigo]

Dennis,

Bike been sitting in a cold garage all winter?  Was she prepped for winter, like with stable or other fuel stabilizer? Any gas smell coming from her after a ride?  Might want to buy some Seafoam and run it though a couple of tanks. Let it idle also with the Seafoam in it.  

Might want to check the air filter as well.

I think your pilot jets may have some varnish in them.  Just a theory.  Might just clean it up and save yourself some work.

Regards,

CraigO
90FJ1200

[cyclenutk75]

I'm about do for a new air filter, and was thinking about going to pods, but If I do so will I have to rejet the carbs, and if so will it make my gas mileage even worse?  I frequently ride to work instead of taking my truck and I'd like to get the best mileage possible.  I certainly don't need any more oomph than my bike already has, especially if it means a hit in my mileage.  Any suggestions?  Cheers in advance for any help!

Dennis

My experience with combustion tells me "more air in, more gas required."  Otherwise, your mixture will be lean.  More gas in means mpg will drop.

[E Double]

Dennis,

Bike been sitting in a cold garage all winter?  Was she prepped for winter, like with stable or other fuel stabilizer? Any gas smell coming from her after a ride?  Might want to buy some Seafoam and run it though a couple of tanks. Let it idle also with the Seafoam in it.  

Might want to check the air filter as well.

I think your pilot jets may have some varnish in them.  Just a theory.  Might just clean it up and save yourself some work.

Regards,

CraigO
90FJ1200

Craig,

Thanks for the reply.  I rode all winter, with the exception of three weeks in January when we had all of the snow.  Luckily for me my garage is connected to the house; The coldest I've ever seen it in there was the low 50's, and that was when it was 5 degrees outside.  Usually it's in the upper 50's to low 60's inside all winter.  I ran a few bottles of Sea Foam through it over the winter, basically whenever I thought I wasn't going to ride at least once every week to ten days. Typically I went out more than I didn't, putting about 3K miles on it since January.  I also ran a tank of sunoco 100 octane racing fuel through it immediately following the three week snow break.  I put some in every two or so months just to blow it out.  I wish I could run it more frequently, but at almost $8 a gallon I have to get it as a treat. I'll put some in next week just to tighten it up; hopefully that will help.  I'll also check the filter. Cheers

[andyb]

Sticking brakes, chain wear, other parasitic losses...

[carsick]

Float level too high or needle seats leaking a bit, ovalled emulsion tubes? Are the emulsion tubes original or were they replaced with the jet kit? Higher ethanol level in the gas you're using? What was the mileage with the 100 octane?

[E Double]

I'm drawing a blank on the status of the emulsion tubes, as I am my mileage with the 100 octane.  I'm going to be filling the tank up with it next week so I'll report the mileage then.  I want to say it was around 38-39 mpg, but I've been wrong before.  The fuel is definitely a possibility, because I've found that the way this particular bike tells me it doesn't like the gas is by the mileage.  It'll still run fine.  And I noticed this year that the bike can't sit for more than 10 or so days without some seafoam in the tank without having problems starting the first time I would fire it up.  Also my truck's ('98 F150 2wd, 4.6) mileage has been fluctuating too;  Over the winter my worst mileage was 13.5 doing mixed driving;  I typically see 16-17 mixed and 19 highway.  The gas definitely sucks, that's for sure.  If I don't see an improvement after a tank of the 100 I'm gonna take it over to my favorite local shop (Sun Cycles, Manasquan, NJ) and have them put it on the dyno.  Money's a little tight,  but I don't get on with riding/driving a vehicle around when it may need something so I'll have to do what I'll have to do.

[FJ111200]

OK this is a real long shot.
In winter fuel contracts in size so you get more for your money, then as the temps creep up the fuel expands a bit so you don't get as much for your money.
Told you it was a long shot 

[Flying Scotsman]

Unless you have a need for the 110 octane it will actually hurt performance and mpg.
If your running 12-1 comp with 5 % advanced timing then you need high octane if you have stock comp then you dont.
Get new plugs and look at the carbs,when did you last sync them.Go though them and check float heights.
I dont see 110 octane as helping mpg 

[Pat Conlon]

 Typically I get between 36 and 38 MPG, but recently (the last three tanks of gas) I've been around 32, 33mpg.  No difference in riding style, terrain, or anything else.........

OK this is a real long shot.
In winter fuel contracts in size so you get more for your money, then as the temps creep up the fuel expands a bit so you don't get as much for your money.

I think our British friend is on to something .... Here's why:
Hey Dennis, you know that the EPA requires the oil companies to sell different blends of fuel, based on the season, correct?
The cold temp. winter blend is different than the hot (warm) weather summer blend.
A 10-15% variation in gas mileage could be due to the difference between the summer/winter blends.
Before freaking out and start changing things, let the season mature until the warm weather blend hits the pumps, then check your mileage.

[andyb]

Winter fuel formulations I didn't think applied everywhere?  Another question is if ethanol was recently added to your local pump.

Sounds like a fairly big loss in a percentage basis, but if the car is doing it as well, try getting fuel elsewhere. The tanks that are changed over first will be the most popular one, probably a lo-test fuel in a convenient station.

[E Double]

I get fuel all over; This is especially the case with the bike.  Typically I fill up local and then do a 250-350 mile ride every weekend.  I'll fill up at about 150-175 typically at the middle of the ride, which is always away from Toms River.  I will say this;  I've put about 1200 miles on the bike over the last month and every time I've gotten fuel in NW NJ (Warren, Hunterdon, and Sussex Counties, About 100 miles NW of me) I've been consistently getting better mileage per tank than I do at the local stations (Shell, Sunoco, Wawa- I try to rotate where I get fuel from locally after getting a bad tank of gas in my wife's car at a station she frequents)over the past 6 or so weeks.  Its just odd because I got better mileage all winter (with the exception of one or two tanks in the dead of winter, when I was putting sea foam in and running a lot of heated gear) than the last two weeks, typically 36 or so mpg.  I saw a drop from around 37-38 mpg when October came around, which is when the crappy winter gas comes online, and then it stayed at 36 all winter until now.  Who knows? maybe they have excess winter gas to get rid of and they're dumping it locally?  As for the ethanol the stations around here have been running 10% for years;  In fact I can't recall a time when they didn't in the years I've been in the area.

I think Pat has the right idea though, with waiting a bit to see if the warmer weather brings my mileage back up.  Its running like a top (really as it always does) and there are other things on the bike which will soon need my attention, such as a new rear rotor and pads and fresh rubber for the summer.

[Kopfjaeger]

just blame gravity and friction. i do.

[wakdady]

no to threadjack but i'm having the exact same problem. only thing is, i've completely rebuilt my carbs. i went with Pat's suggestion of #40 pilot jets and adjustable needles set at the #2 clip. 2.5 turns out.
stock airbox with uni filter and V&H 4-1. but my mpg is horrible. last tank i got 100 miles to 4 gallons. that 25mpg! i did rail on it a little, but that's a bit much.

what kinds of mileage do you guys experience while giving it the beans? i tend to ride pretty fast. but even when i'm flying with my r6, i still get 150 miles to 3.5- 4 gallons

i do have the colortune and gave that a shot, but i haven't really seen a difference. it's got all new wheel bearings and front brakes are newer r1 calipers. the rear is OE, i'll check it but that doesnt seem like the problem.

WTF? any suggestions?

[racerrad8]

WTF? any suggestions?

Emulsion tubes...?

I don't think you got those when you bought all of the other parts, but I do not recall for sure. If they are ovaled out the bike will be rich.

Plus, I can tell you that I noticed my tow van I used to go racing last weekend only got about 11mpg compared the the normal 14-15. The fuel might be the cause since we live here in the "green" state of California.

I have also gone away from running "premium" pump gas in my race cars this year as I was seeing higher head temps due to the alcohol content, I have gone back to running 100 octane race gas.

Randy - RPM