hmmm... only 70Miles to a tank... I think I got an issure here

joedude · July 17, 2006, 12:01:02 PM

So I rejetted a while ago, and havn't been riding around much... but yesterday I went out for my first long ride, and after only 67Miles, I had to switch to reserve!!! That's only 16.7 MPG!!!! What the @#%$&? She's got plenty of power in pretty much every range... anyone have any ideas as to what the heck is going on with my bike?

Egaeus · July 17, 2006, 12:03:01 PM

Do you have a fuel leak? Is your odometer working correctly? Did you fill the tank the same way both times?

joedude · July 17, 2006, 12:05:52 PM

Quote from: Egaeus on July 17, 2006, 12:03:01 PM
Do you have a fuel leak? Is your odometer working correctly? Did you fill the tank the same way both times?

No fuel leak, both times I had same fuel mileage (first time, with my bike sitting for a week - I thought it could be a leak too... but yesterday I fueled up and drove the whole 60 miles so it couldn't have leaked as much during a week as in an hour)

Odometer seems correct considering the drive I took.

Tank was full both times about 14Litres.

Codger · July 17, 2006, 12:48:48 PM

Pull the plugs and see if they are truly burning rich.

rangerbrown · July 17, 2006, 03:25:04 PM

thats till way rich, if it is. theres no way thats right.

did you do the math right?

un1261 · July 17, 2006, 03:48:23 PM

would it even run that rich?

joedude · July 17, 2006, 07:02:33 PM

Quote from: rangerbrown on July 17, 2006, 03:25:04 PM
thats till way rich, if it is. theres no way thats right.

did you do the math right?

well you do the math... 67 miles... on a 4 gallon tank

67 / 4 = 16.75 MPG

I think that's right eh?

But seriously now... That's less than half of what the true mileage should be... that's HUGELY way off. I find it hard to believe that the bike could be running that rich when I have the proper jets according to the rejet matrix. Furthermore... adjusting the mixture setting changes the running of the bike... so I doubt that that fuel is going into the engine (we're talking more than twice the amount of fuel over normal here - I don't think the engine would run at all like that!)

I'll pull the plugs to see what they're saying... and I'll check under the bike for puddles but I havn't seen any yet.

Thanks for the input so far! Keep the ideas coming!

Kerry · July 17, 2006, 07:29:26 PM

Hang on. You're dividing by 4 gallons, but your 4.5 gallon tank should have about 1 gallon left when you first go on REServe. In addition, you may not be starting out with a full 4.5 gallons, depending on the technique you use to fill up.

The only accurate way to do this is to fill up using the SAME method that you used just before your ride, and divide your trip miles by the ACTUAL number of gallons you pumped in.

rangerbrown · July 17, 2006, 07:52:31 PM

yea, at the most i get 230-260 miles then reserve.

at top off i get about 4.1-4.2 gal

245/4.1=59.7mpg

ukchickenlover · July 17, 2006, 11:40:35 PM

Did you get 67 miles and then go fill it with 4 gallons or have you not filled the tank yet. Sounds very very strange to me. I took a cbr around donington park and got 35mpg revving the cr#p out of it. I normally get about 50mpg.

Richmore · July 18, 2006, 01:29:25 AM

I am having more or less the same problem, i get around 77 - 80 miles per fill once switching to RES... the bike is running really really rich and will not idle i have the idle screw set to about 4500 rpm and it still slowly begins to struggle then.

I think my jets are too big, or at least th epilot jet is... have you thought about going down some jet sizes and see if that makes a difference?

How is the bike when starting from cold/warm??

lachie · July 18, 2006, 02:15:51 AM

can fuel leak from the carbs back into the air box?? then out the airbox drain plug?

Richmore · July 18, 2006, 02:29:48 AM

Yeah it can, if this happens it generally means that the float needle is failing to shut of the fuel filling into the float bowls.

Bare in mind that if it leaks back into the airbox and drains it's possibly also leaking down into the cylinders and possibly past the cylinder rings into the oil.

joedude · July 18, 2006, 06:24:13 AM

Quote from: Kerry on July 17, 2006, 07:29:26 PM
Hang on. You're dividing by 4 gallons, but your 4.5 gallon tank should have about 1 gallon left when you first go on REServe. In addition, you may not be starting out with a full 4.5 gallons, depending on the technique you use to fill up.

The only accurate way to do this is to fill up using the SAME method that you used just before your ride, and divide your trip miles by the ACTUAL number of gallons you pumped in.

I'm dividing by 4 gallons because that's what I put in the tank from last fill both times (I ended up using a bit of the reserve)

I put in 15.4 Litres the first time ( 15.4 L / 3.785 = 4.07 USG ) On that tank I ran 71 Miles ( 71 Mi / 4.07 USG = 17.44 MPG )

And 14.8 Litres the second time ( 14.8 L / 3.785 = 3.91 USG ) On that tank I ran 67 Miles ( 67 Mi / 3.91 USG = 17.13 MPG )

For me to be within .1 of a gallon both sides of 4 Gallons I think is a pretty good indication of me filling my tank EXACTLY the same way both times. I even think I went to the same pump!

Quote from: lachie on July 18, 2006, 02:15:51 AM
can fuel leak from the carbs back into the air box?? then out the airbox drain plug?

I don't have an airbox... K&N Lunchbox filter

Quote from: Richmore on July 18, 2006, 01:29:25 AM
I am having more or less the same problem, i get around 77 - 80 miles per fill once switching to RES... the bike is running really really rich and will not idle i have the idle screw set to about 4500 rpm and it still slowly begins to struggle then.

I think my jets are too big, or at least th epilot jet is... have you thought about going down some jet sizes and see if that makes a difference?

How is the bike when starting from cold/warm??

My bike seems to run better since I've rejetted the bike. It's an american bike that I've imported into Canada so I had to bring then pilot one size up just to compensate for the generally colder/denser air up here. and besides my bike doesn't Idle long enough to burn that much gas!

The bike starts with 1/4 choke on first crank with a little blip of throttle every time. Idles at about 2500-3000 RPM until I open the Choke and then it settles to a comfortable 1200-1300 RPM.

Kerry · July 18, 2006, 10:07:02 AM

Quote from: joedude on July 18, 2006, 06:24:13 AMI'm dividing by 4 gallons because that's what I put in the tank from last fill both times

[...]

For me to be within .1 of a gallon both sides of 4 Gallons I think is a pretty good indication of me filling my tank EXACTLY the same way both times. I even think I went to the same pump!

That's good enough for me! Any chance that there's a neighborhood thief who uses a consistent technique to steal gas?

Egaeus · July 18, 2006, 10:13:42 AM

I honestly can't think of anything that could cause this except for a leak either between the carb and petcock or in the carb itself. That way it would only leak when the engine's running. Try letting it sit on the centerstand with the petcock in PRI and see if it leaks then.

News:

hmmm... only 70Miles to a tank... I think I got an issure here