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My 2008 1800t has been running slightly off, a little less power and a little less fuel economy. I regularly got 37-38 mpg now I get about 33. My bike is preformance wise mostly stock except for pair valve removal and desmog Here is a chronological, more or less, list of what I have done to track down the problem.
New air filter and cleaned the plugs
I removed the cobra fuel programmer( AT Black)
Added Sea Foam to 2 tanks of gas
Checked for vacuum leaks
Replaced the plugs with NGK IFR5L11
Ran another tank of Sea Foam
With the ngk plugs I could tell that the right rear plug is running too rich
Trimmed the plug wire and made sure it was seated well
I swapped coils front to back and the problem didnt move, still right rear plug too rich
Checked grounds and made sure the connections to the coils were tight
I ordered a new Factory plug wire assembly
The battery load test correctly and the connections are tight and the bike starts easily
today I pulled the leads off the injectors and checked the ohms, they are about the same. I am out of ideas the right rear plug is always darker than the other 3

A person on this board (I Think) once said "These bikes approaching 15 years old, there are no new problems just problems new to you(me) Any help will be appreciated
 

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Discussion Starter #2
My 2008 1800t has been running slightly off, a little less power and a little less fuel economy. I regularly got 37-38 mpg now I get about 33. My bike is preformance wise mostly stock except for pair valve removal and desmog Here is a chronological, more or less, list of what I have done to track down the problem.
New air filter and cleaned the plugs
I removed the cobra fuel programmer( AT Black)
Added Sea Foam to 2 tanks of gas
Checked for vacuum leaks
Replaced the plugs with NGK IFR5L11
Ran another tank of Sea Foam
With the ngk plugs I could tell that the right rear plug is running too rich
Trimmed the plug wire and made sure it was seated well
I swapped coils front to back and the problem didnt move, still right rear plug too rich
Checked grounds and made sure the connections to the coils were tight
I ordered a new Factory plug wire assembly
The battery load test correctly and the connections are tight and the bike starts easily
today I pulled the leads off the injectors and checked the ohms, they are about the same. I am out of ideas the right rear plug is always darker than the other 3

A person on this board (I Think) once said "These bikes approaching 15 years old, there are no new problems just problems new to you(me) Any help will be appreciated
This started as best as I can recall, shortly after I installed the Cobra fuel programmer and has been going on for about a year.
 

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Discussion Starter #3
This started as best as I can recall, shortly after I installed the Cobra fuel programmer and has been going on for about a year.
When I say it runs a little off for example at 55-60 in 5th gear when i give it gas it lugs until 70 mph
 

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When I say it runs a little off for example at 55-60 in 5th gear when i give it gas it lugs until 70 mph
That in itself isn't that unusual.
 
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Yep, getting hard on the gas at 55 it will lug until it gets up to 70 when you're in 5th.
The fuel mileage might be attributed to winter fuel mixes, depending where you live, or a sudden switch from straight gasoline to using ethanol blended fuels again, dependant on where you live.
"Checking the grounds to be sure they're tight" is not what we mean by "Doing the Ground Fix" If you do not take the ground apart and clean each of the wire grounds up, the ground bolt and the frame ground with wire brushes and put them back together, then you haven't done the ground fix. They can look fine, but until you clean the corrosion that sits between the different metals, this will continue to be a poor ground and cause poor running
 

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Discussion Starter #6
Yep, getting hard on the gas at 55 it will lug until it gets up to 70 when you're in 5th.
The fuel mileage might be attributed to winter fuel mixes, depending where you live, or a sudden switch from straight gasoline to using ethanol blended fuels again, dependant on where you live.
"Checking the grounds to be sure they're tight" is not what we mean by "Doing the Ground Fix" If you do not take the ground apart and clean each of the wire grounds up, the ground bolt and the frame ground with wire brushes and put them back together, then you haven't done the ground fix. They can look fine, but until you clean the corrosion that sits between the different metals, this will continue to be a poor ground and cause poor running
Thanks for your replies, but too be clear I dissasembled and sanded the grounds in 2012 when I got the bike and consistantly got about 37+ mpg till this past year
 

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You need to do the grounds every few years. It's not a One and Done item. Galvanic corrosion between various different metals continues to happen.
 

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You should be in 4th gear til you are going at least 60. 65 even better (smoother). RPMs float the journals, keep that thing spinning.
 

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How many miles? If you have high miles I am betting your injector seal or injector is leaking. You can switch the injectors to see if the problem moves from rear to front. The spark plug would look black and sooty. This could also be from riding to low in the RPM range if you do it a lot. I doubt that is it because you have not had the problem before. Stock plugs that came with the bike especially the later year bikes are the best plugs for the bike. If you have a fuel injection shop around you can have them test the spray pattern the Honda fuel pressure is 50 psi. Good luck
 

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Discussion Starter #10
Thanks, for the idea. Just to be sure I re-sanded the all the grounds Thursday and rode about 250 miles. Still poor fuel mileage and no acceleration. I have put about 47k miles on this bike so I know its not preforming correctly. I will swap injectors and see if the problem moves
 

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My 2008 1800t has been running slightly off, a little less power and a little less fuel economy. I regularly got 37-38 mpg now I get about 33. My bike is preformance wise mostly stock except for pair valve removal and desmog Here is a chronological, more or less, list of what I have done to track down the problem.
New air filter and cleaned the plugs
I removed the cobra fuel programmer( AT Black)
Added Sea Foam to 2 tanks of gas
Checked for vacuum leaks
Replaced the plugs with NGK IFR5L11
Ran another tank of Sea Foam
With the ngk plugs I could tell that the right rear plug is running too rich
Trimmed the plug wire and made sure it was seated well
I swapped coils front to back and the problem didnt move, still right rear plug too rich
Checked grounds and made sure the connections to the coils were tight
I ordered a new Factory plug wire assembly
The battery load test correctly and the connections are tight and the bike starts easily
today I pulled the leads off the injectors and checked the ohms, they are about the same. I am out of ideas the right rear plug is always darker than the other 3

A person on this board (I Think) once said "These bikes approaching 15 years old, there are no new problems just problems new to you(me) Any help will be appreciated
You might want to try a couple tanks with Techron injector cleaner I think its the best stuff out there. I also have the 2008 1800T and about every 10 tanks I put some Techron in. My bikes only at 20,000 miles but I ride in traffic a lot and I have had luck with Techron with other vehicles good luck
 

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I have a 2006 VTX1800C2 that had 5,000 when I bought it 12/31/18, and now has 19,100. Minx isn't running as smoothly as it used to. What grounds should be cleaned and how to adjust the valves?
 

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I have a 2006 VTX1800C2 that had 5,000 when I bought it 12/31/18, and now has 19,100. Minx isn't running as smoothly as it used to. What grounds should be cleaned and how to adjust the valves?
It would have been better to start your own thread.
Check the spark plugs, they provide info.
Are both exhaust pipes hot?? Sometimes a single cylinder drops.
Do you have a fuel manager???
What modifications have you done???
Have you checked battery connections?? Common to have loose connections.
Step by Step has the "Ground fix" in 1800 section.
Do that part at the "Common Electronics ground bolt" at the Front ignition coil.
Gen2 has a Ground cable from the starter motor mounting bolt to a bracket
between the down tubes.
One person posted about that ground cable many years. Rarely mentioned.
Clean & Lube...

Add some Techron to tank. Use the ounces per gallon...
 

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Discussion Starter #16
Tar Snake , thanks for the idea, but I just forgot to list that on my actions taken. About 1000 miles ago, Aug- Sept. I am going to try to swap injectors as Backstabber thought of as I am out of ideas. I hope to do it this weekend but the older I get the harder it is to stay bent over a bike for hours. Keep the suggestions coming , I WILL eventually get this sorted out.
 

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You should be in 4th gear til you are going at least 60. 65 even better (smoother). RPMs float the journals, keep that thing spinning.
I usually shift to 5th. around 70 to 75 , with the rpm's up in 4th . It takes off like a rocket. With the limiter not concerned over reveling. Maybe try hotter plugs , it might help.
 
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