Gas mileage gone wrong
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Joined: Nov 2023
Posts: 74
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From: AZ
Gas mileage gone wrong
My 1998 Fat Boy almost all stock except stage 1 intake and Vance & Hines radius pipes is getting 20mpg no 💩. Runs great not to rich well how could it be to the tune of missing 20mpg no leaks except peacock when I turn it to off but I measured the amount it drips thinks full at most.
No leaks while riding so wtf is the fuel going?? This is a huge pain in the a$$ I took it to a certified Harley guy today he said maybe I need cone baffles no back pressure bikes working to hard idk bro to the tune of 50% gas milage loss hard lol I have a hard time believing that im Baffled!! Any suggestions i appreciate any help here thanks 🙏
No leaks while riding so wtf is the fuel going?? This is a huge pain in the a$$ I took it to a certified Harley guy today he said maybe I need cone baffles no back pressure bikes working to hard idk bro to the tune of 50% gas milage loss hard lol I have a hard time believing that im Baffled!! Any suggestions i appreciate any help here thanks 🙏
Seasoned HDF Member
Joined: Dec 2006
Posts: 8,216
Likes: 6,129
From: Black Hills
My built 80" + evo gets 45-50 MPG with a Wood CV40 high flow carb. There's no reason you shouldn't be able to hit 40 MPG with it. Like mentioned above check you jets. Has the carb been cleaned recently ?
I've found there are a lot of guys who don't understand the CV40 and will call it junk because they can't get it dialed in so they replace them with other makes that they do understand and can dial in. I'd check around and find someone who can fix this setup - what you have should perform much, much better.
I've found there are a lot of guys who don't understand the CV40 and will call it junk because they can't get it dialed in so they replace them with other makes that they do understand and can dial in. I'd check around and find someone who can fix this setup - what you have should perform much, much better.
Road Warrior
Joined: May 2017
Posts: 1,343
Likes: 2,057
From: Phoenix
I'm assuming you're still running the vacuum operated petcock. My bet is the diaphragm in it is torn. Fuel is getting sucked into your intake manifold from the torn diaphragm.
I think the petcocks also have a weep hole to drip through when bad.
I think the petcocks also have a weep hole to drip through when bad.
Seasoned HDF Member
Joined: Feb 2007
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From:
How do you measure mileage per gallon?
You state.
No leaks EXCEPT peacock when I turn it Off.
A tiny leak while riding and a tiny leak at shut off can easily translate to reduced miles per gallon.
You state.
No leaks EXCEPT peacock when I turn it Off.
A tiny leak while riding and a tiny leak at shut off can easily translate to reduced miles per gallon.
Road Captain
Joined: Oct 2020
Posts: 518
Likes: 593
From: Central Iowa
First, you know the petcock leaks and it is reducing fuel mileage to some degree so the very first thing I'd do is to fix the leak and completely eliminate that as a contributing factor, it needs to be repaired regardless so you have nothing to lose and everything to gain. After that's done and there are no more fuel leaks, and if you're measuring the fuel fuel consumption accurately, then it's running rich. There's tons of articles and videos online on how to read sparkplugs, and how to tune a CV carburetor.
https://cv-performance.com/instructions-guides
https://cv-performance.com/instructions-guides
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Road Master
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Joined: Nov 2023
Posts: 74
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From: AZ
Thanks everyone For the info I ordered a pingel its on the way.
The 20mpg is a huge loss like it has to be dumping somewhere Im thinking its flooding the engine perhaps the float isnt working properly either but I put a new 50$ amazon carb on there just as a control test seems a little better already
my old carb had a 170 and 50 jets the new one 170 and a 45 but the float works better more responsive on the new one perhaps the old carb was just dumping it thru the overflow due to the float being worn out. Damn floats are important lol. I am learning mucho about CV carbs and I love them so easy and great design. I do wonder how the S&S perform and if its worth it?
thanks again I love this forum!
Ride Hard,
Johnny
The 20mpg is a huge loss like it has to be dumping somewhere Im thinking its flooding the engine perhaps the float isnt working properly either but I put a new 50$ amazon carb on there just as a control test seems a little better already
my old carb had a 170 and 50 jets the new one 170 and a 45 but the float works better more responsive on the new one perhaps the old carb was just dumping it thru the overflow due to the float being worn out. Damn floats are important lol. I am learning mucho about CV carbs and I love them so easy and great design. I do wonder how the S&S perform and if its worth it?
thanks again I love this forum!
Ride Hard,
Johnny
