MPG with an old Evo
Road Warrior
Joined: Apr 2016
Posts: 1,529
Likes: 933
From: Long Island
Yeah , but now you have a hot rod motor.lol
Road Captain
Joined: Apr 2009
Posts: 501
Likes: 150
From: Jersey
Tuning
Greetings.
I ride an '88 Electra Glide (FLHTC) with a 1337 cc Evolution and a 42mm (I think) Mikuni carburetor.
The odometer reads greater than 90K.
It starts promptly, idles well, and runs smoothly.
The plugs are clean.
It's tuned... seemingly well.
It's a pleasure to ride.
While running well, at best it delivers about 29.5 MPG.
When I keep the tach at or above 3000, the MPG goes down... but the engine purrs.
With no complaints or concerns, I'm curious what kind of mileage other vintage Evo riders are getting.
Will changing the carburetor jets improve the mileage per gallon?
Comments?
I ride an '88 Electra Glide (FLHTC) with a 1337 cc Evolution and a 42mm (I think) Mikuni carburetor.
The odometer reads greater than 90K.
It starts promptly, idles well, and runs smoothly.
The plugs are clean.
It's tuned... seemingly well.
It's a pleasure to ride.
While running well, at best it delivers about 29.5 MPG.
When I keep the tach at or above 3000, the MPG goes down... but the engine purrs.
With no complaints or concerns, I'm curious what kind of mileage other vintage Evo riders are getting.
Will changing the carburetor jets improve the mileage per gallon?
Comments?
Seasoned HDF Member
Joined: Aug 2008
Posts: 5,081
Likes: 2,159
From: Ohio
Beg to differ, been running Mikuni's on various Harley's for 30 years and PROPERLY tuned they are Great carbs and can certainly improve rideability, power and milage. The key is to tune it correctly using the Manual provided by Mikuni. Don't have one? Go to their website. BTW: Built 88 FLHS, big cam, high compression and lots of other goodies, 90/90 and over 40 MPG.
Joe Minton wrote the Mikuni Tuning manual your using for reference, read my attachment and compare to your book, with 30 years of tuning experience you should know Joe Minton's contribution to Harley's. The mileage kit is a very good starting format based on Joe's experience, it does work based on first hand experience tuning with a Wego.
Last edited by 1997bagger; Mar 26, 2019 at 10:19 PM.
Road Captain
Joined: Apr 2009
Posts: 501
Likes: 150
From: Jersey
What are you debating in my comment? Are you questioning the mileage kit? Questioning my input on being rich out of the box? I said they were good carbs? Help me out here.
Joe Minton wrote the Mikuni Tuning manual your using for reference, read my attachment and compare to your book, with 30 years of tuning experience you should know Joe Minton's contribution to Harley's. The mileage kit is a very good starting format based on Joe's experience, it does work based on first hand experience tuning with a Wego.
Joe Minton wrote the Mikuni Tuning manual your using for reference, read my attachment and compare to your book, with 30 years of tuning experience you should know Joe Minton's contribution to Harley's. The mileage kit is a very good starting format based on Joe's experience, it does work based on first hand experience tuning with a Wego.
Cruiser
Joined: Jul 2015
Posts: 166
Likes: 13
From: Beaufort, NC
My 94 road king wore out the needle and jet holder on a dynajet drop in kit and slowly started getting worse and worse mileage as the miles racked up, as I guess it was hanging up the slide. I'd consider grabbing a new needle and needle jet and see if things pop back up into the forties on your machine.
My setup now is a 42 slow speed, 88 sportster needle, and a 175 main jet. Doesn't have any bad habits and does around 38-44 mpg depending on speed and wind. I wouldn't mind having a touch leaner mid-rpm needle, as running down the road at 70-75 (more the 38 side of that mpg range...) I get a bit of brown/tan deposit in the tail pipes. Might try the velocity version that has a touch longer straight section than the harley part 88 needle. Ev27 cam, stock late model exhaust (tow a camper and grabbing a fist full with the true duals that were on it sounded like a P51 mustang chasing me...) and a screaming eagle air cleaner.
My setup now is a 42 slow speed, 88 sportster needle, and a 175 main jet. Doesn't have any bad habits and does around 38-44 mpg depending on speed and wind. I wouldn't mind having a touch leaner mid-rpm needle, as running down the road at 70-75 (more the 38 side of that mpg range...) I get a bit of brown/tan deposit in the tail pipes. Might try the velocity version that has a touch longer straight section than the harley part 88 needle. Ev27 cam, stock late model exhaust (tow a camper and grabbing a fist full with the true duals that were on it sounded like a P51 mustang chasing me...) and a screaming eagle air cleaner.
Seasoned HDF Member
Joined: Aug 2008
Posts: 5,081
Likes: 2,159
From: Ohio
It's all good, a fan of Mikuni carbs like your are.
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Advanced
Joined: Sep 2016
Posts: 67
Likes: 21
From: SoCal
I track my mileage pretty closely:
I averaged 32MPG over 2300 miles on my 1991 Heritage Softail w/S&S carb and likely some engine work (bought used with no records, ran really strong). It was definitely running rich but I never made the time to buy replacement jets to play with it. Started great, ran great. The only complaint was I needed to start looking for gas at around 110 miles as my range was probably only about 125 miles.
My current 1998 Heritage Springer Softail is stock with the CV carb, no engine work. Over the 600 miles I've had it, I'm averaging right at 42MPG. I played with different CV jets and needle as well as the mixture screw and have the bike running pretty good. I figure I can get to around 150 before needing reserve and expect an overall range of about 175 miles. I'd LOVE to get 50+MPG but, 42 is good enough for now.
If you're only getting ~30MPG, you need to tune your carb (likely different cab needles). I've read that Mikuni's are excellent carbs but can be a bit tough to fine tune. I'm cheap and would try to tune it myself but, that failing, I would find an old-timer mechanic, pay for a tune, and consider it money well spent.
I averaged 32MPG over 2300 miles on my 1991 Heritage Softail w/S&S carb and likely some engine work (bought used with no records, ran really strong). It was definitely running rich but I never made the time to buy replacement jets to play with it. Started great, ran great. The only complaint was I needed to start looking for gas at around 110 miles as my range was probably only about 125 miles.
My current 1998 Heritage Springer Softail is stock with the CV carb, no engine work. Over the 600 miles I've had it, I'm averaging right at 42MPG. I played with different CV jets and needle as well as the mixture screw and have the bike running pretty good. I figure I can get to around 150 before needing reserve and expect an overall range of about 175 miles. I'd LOVE to get 50+MPG but, 42 is good enough for now.
If you're only getting ~30MPG, you need to tune your carb (likely different cab needles). I've read that Mikuni's are excellent carbs but can be a bit tough to fine tune. I'm cheap and would try to tune it myself but, that failing, I would find an old-timer mechanic, pay for a tune, and consider it money well spent.
Stellar HDF Member
Joined: Nov 2010
Posts: 3,117
Likes: 1,145
From: Directly above the center of the Earth
I consistantly get 45 mpg on my '98 with an EV13 cam and Super E carb. If I get on the interstate and do 75+ mph, it goes down to around 39 or 40 mpg. This is with the 90 octane non-ethanol gas I use most often in my bike.
If I fill up the tank and it has more than 50% of the other gas (the 92 octane corn ****), then my bike *consistantly* gets 4 mpg less at the same speeds.
I had a CV carb on it when I first got it and I couldn't get the bike to run right or give good gas mileage for the life of me. I tried for almost 2 years. Finally gave up and as I was wondering what to do my brother gets me the S&S carb for kisstmuhass or my birthday...can't remember. Popped it on the bike and once I got the jetting set correctly and the other adjustments on it, it's been that way since and running perfectly.
Hopefully with your bike and carb it just needs a simple tune-up and/or cleaning to get to better gas mileage and you don't have to troubles I had with the stock CV.
If I fill up the tank and it has more than 50% of the other gas (the 92 octane corn ****), then my bike *consistantly* gets 4 mpg less at the same speeds.
I had a CV carb on it when I first got it and I couldn't get the bike to run right or give good gas mileage for the life of me. I tried for almost 2 years. Finally gave up and as I was wondering what to do my brother gets me the S&S carb for kisstmuhass or my birthday...can't remember. Popped it on the bike and once I got the jetting set correctly and the other adjustments on it, it's been that way since and running perfectly.
Hopefully with your bike and carb it just needs a simple tune-up and/or cleaning to get to better gas mileage and you don't have to troubles I had with the stock CV.