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Buell Forum » Old School Buell » Archive through October 02, 2010 » Fuel Economy.....What the heck is going on? « Previous Next »

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Ft_bstrd
Posted on Sunday, September 12, 2010 - 06:19 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

Rode today. Stock Exhaust. Stock Intake. Have no idea what the PO did, if anything to the jetting/adjustment of the carb.

New plugs, properly gapped.
New plug wires.
Clean Filter.

Ran the tank dry at 101 miles. Rode another 6 miles to the station and put in 3.264 gallons.

So that's 107 miles at about 32MPG.

Now, in timing my odo against mile markers, my odometer is persistently 20% off (shows 8/10ths elapsed mileage at each mile marker.

So even at 20% off, it still puts the mileage just shy of 40MPG. Now I'm a big bastard with a large cross section and VERY poor throttle discipline, but even 40MPG seems low. There are folks with intake, exhaust, and jetting getting 50MPG+.

How can I tell what the current jetting of the carb is (assuming PO increased the jets for the V&H pipe that was on it when I got it)?

Clue: Discovered an exhaust leak today. front of motor heading backwards towards the rear (VR/Muffler Mount, lower portion of clutch cable, primary case, shifter lever, etc.) were covered in black soot. To me this would indicate a rich running condition.

I have had the old V&H pipe repaired and will be reinstalling it.
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Guell
Posted on Sunday, September 12, 2010 - 06:27 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

pull the carb, the jets will be stamped with what they are.

Thats terrible mileage. Im running a race intake, kooks full system, race ign and i constantly hit 6k rpm while out riding and i average 50mpg. Mines jetted rich too. Im going to drop it back to a 195 and see how it runs. The 200 is a bit much i think with my set up
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F_skinner
Posted on Sunday, September 12, 2010 - 06:30 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

FB, do you get a strong gas smell???

You should be getting better that 40. A lot has to do with the way you ride but if your going for gas mileage you should be doing a lot better than under 40. I recommend taking the carb off and rebuilding it making sure to clean it well and rejet if you need to (check the jet size and report back). Also, the stock exhaust will provide more back pressure than an open exhaust and will do great around town. On the highway an open exhaust does better MPG wise... It is a trade off.

I know my odometer is off as well... I know this is because of the speedo drive gear and I need to take if off and clean it (not sure if your M2 has one like that). I did 175 miles on a tank and had not hit reserve this weekend. I indicated well over 200... I have achieved 240 miles to a tank without hitting reserve but that was special circumstances.

Make sure you do not jet the bike too lean... Better too rich than too lean...
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Guell
Posted on Sunday, September 12, 2010 - 06:38 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

for a good starting point would be upping to a 45 slow jet, leaving the main alone if its stock and 2.5 turns out on the adjuster.
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Oldog
Posted on Sunday, September 12, 2010 - 11:20 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

Ft_ the speedo is electonic, and has a pickoff in the gear box on the case above the front pully IIRC, some have indicated that if the nose gets crapped up it can cause problems, I presume that the gearing is stock. my X1 consistantly reads about 5 mph faster than my ground speed is.
( checked against my gps ) my mpg comes in in the low 40s with the race box and high 40s with the epa box
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Littlebuggles
Posted on Monday, September 13, 2010 - 12:59 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

I get about 43 around town... with a lot of heavy throttle take offs, only 47 on the interstate.
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Ratbuell
Posted on Monday, September 13, 2010 - 01:06 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

Tire pressures?
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Ft_bstrd
Posted on Monday, September 13, 2010 - 01:16 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

Tire pressures are good.
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Blake
Posted on Monday, September 13, 2010 - 07:02 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

I've heard about some folks installing a bigger main jet. It's a bad idea. Even with 100 RWHP, my old Cyclone still uses the stock main jet and will run too rich on hot Summer days. The needle is sometimes shimmed too much too.
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Natexlh1000
Posted on Monday, September 13, 2010 - 10:07 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

It may not be a jetting issue.
If the timing is off, your combustion efficiency would be crappy.
I complained to an old timer mechanic in Oklahoma city that my bike was pinging.
He poked the timing back a bit and sure enough, my pinging was gone.
So was my performance and fuel efficiency!
No more wheelies and MPG went from 52 to 35
Pretty easy to put a timing light on it and see, right?
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Ft_bstrd
Posted on Monday, September 13, 2010 - 10:33 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

The fuel economy is crap and I can time getting to 100MPH with a calendar (and can't get past 100MPH with a hurricane at my tail).

Don't have a timing light. I'll have to find someone with one (or borrow one from O'Reilly's).
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F_skinner
Posted on Monday, September 13, 2010 - 10:40 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

Is this a sudden thing or did it get bad gas mileage before?
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Ft_bstrd
Posted on Monday, September 13, 2010 - 10:47 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

No, it's always sucked since I've had it. I've been working to macro to micro. Runs and rides great not, but needs a little tune up work.

I need to pull it apart this weekend and check to jetting. Assuming it's stock, it may be the timing.

The bike runs and rides great. Starts first time every time. Runs and idles smooth. Have no beef with it other than the fuel economy is lousy and the top end is "soft".

I don't think it's just me being a big bastard.
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Blake
Posted on Tuesday, September 14, 2010 - 12:09 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

Spark plugs should reveal if it is running way too rich. Might also check the VOES (timing advance via Vacuum Operated Electronic Switch), and I agree, verifying proper timing is a good idea too.
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Ft_bstrd
Posted on Tuesday, September 14, 2010 - 12:46 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

Checked the old ones when I put the new ones in. Looked like they should.
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Xl1200r
Posted on Tuesday, September 14, 2010 - 10:52 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

To get a good plug read if you're having trouble with the top end is to wind the bike up and hit the kill switch while the throttle is open an the revs are high. Otherwise what you're reading off the plug is what it was doing at idle in your garage just before you shut it down.

My MPG is odd as well - usually in the mid-40's on my S3T, but on the first day of my 'big trip' is consistently went up each tank and was as high as 52 mpg by the last tank.

I'm not terribly heavy on the throttle with that bike.
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Ft_bstrd
Posted on Tuesday, September 14, 2010 - 03:16 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

I'm going to check the timing on it and see if that's the issue (plus check the jetting).
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