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MPG through the roof

BigGinger

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Hey guys!

I installed the full system (sounds amazing). Black widow downpipe and scorpion titanium muffler.

It was my first proper trip today and on a fresh tank of fuel. I noticed the MPG shot up quickly and at one point I was averaging 94.3. I got to work (25 miles) and I had 92 at that point. I’ve always struggled to keep it above 80 over the course of a tank and have never had those numbers.

Could it be the new exhaust? Is it wrong/faulty?
 
I think your sample size is too small. Run two or three full tanks through and report back with actual calculations. I wonder if because the bike sounds different, your are riding it differently.

Are you are using imperial gallons (larger than US gallons)? 94.3 miles per imperial gallon is easy for me to obtain on a stock NC, but your riding style and environment will vary.

 
Does the bike have an O2 sensor (from factory)?
I think the 750 does, but at this point, I honestly can't remember if my '12 700 does or not.
If yes, does the new exhaust have an O2 sensor?
It's possible that fuel consumption is linked to that, I know my car has a bad O2 sensor and that SEVERELY affects fuel consumption. If the new exhaust deletes the sensor, or even if it significantly changes the position of the sensor in the stream, it can impact fuel delivery.
Not guaranteeing this is the answer, but might be something to consider.
 
The O2 sensor is in the same position. I’m surprised as I’ve never had numbers that high, even with frugal riding. It’s either fantastic, or wrong. We’ll see.
 
Keep track over a few full tanks and report back. I've had tanks where I had 87mpg and tanks where I've had 55mpg. It tracked well with the traffic and riding style.
 
The O2 sensor is in the same position. I’m surprised as I’ve never had numbers that high, even with frugal riding. It’s either fantastic, or wrong. We’ll see.
If it turns out to be fantastic let us know. I’ll definitely do whatever you did
 
Ive been doing the same journey for 9 months. The most I got after a tank was about 79Mpg. When commuting I ride at 50mph max as that’s where the fuel economy is. I have the odd weekend blast where it can dip into the 50s but commuting has always been very reliable and always in the 70s. To get over 90 is incredible, especially when fuel prices are so high.

Ive told the Mrs that the exhaust is paying for itself
 
Ive been doing the same journey for 9 months. The most I got after a tank was about 79Mpg. When commuting I ride at 50mph max as that’s where the fuel economy is. I have the odd weekend blast where it can dip into the 50s but commuting has always been very reliable and always in the 70s. To get over 90 is incredible, especially when fuel prices are so high.

Ive told the Mrs that the exhaust is paying for itself

I’ll ask once again, do you use imperial or US gallons? Without stating which, the mpg numbers you are mentioning are rather meaningless.
 
Imperial. Not US. 4.546 litres per gallon.
Thank you for clarifying.

You didn’t state (or show in your signature) your exact motorcycle model and year, but you posted in the NC700 General Discussion forum so I’ll assume NC700X. The Fuelly website suggests an average US gallon MPG for all NC700Xs reported is around 65mpg. So just for reference, for your imperial gallons, a good average MPG among many units would be about 78 mpg. https://www.fuelly.com/motorcycle/honda/nc700x
 
Just got home. 90.1mpg so dropped a little as expected. I think I’ll get mid to high 80s over the course of the tank. That’s about 10mpg better than usual. If all works out that way, that’s about 30 miles extra per tank which is brilliant.
 
Just got home. 90.1mpg so dropped a little as expected. I think I’ll get mid to high 80s over the course of the tank. That’s about 10mpg better than usual. If all works out that way, that’s about 30 miles extra per tank which is brilliant.
Your 90.1 today is close to my stock exhaust 700’s average over 58,000 miles of riding: 90.43 miles per Imperial gallon.

As suggested, track this over several tanks and report back. It sounds like a big win for you, whether the exhaust changed the way the engine runs, or changed the way you are riding.
 
A very big win. I’m taller and heavier than the average man. About 26 stone. I am surprised the NC will give me such great results as my weight is like having a pillion on board at all times.

Fantastic bikes.
 
My thinking is perhaps the motor is running even leaner than stock because of the exhaust. On my former 700X the best I ever got (per Imperial) is a little over 80mpg. On my 750 I average around 73.

On the Imperial/US gallon subject Y'all can assume that if a member from the UK or in my case Ireland are talking MPG it will always be Imperial.
 
Not sure I like the idea of running that lean. Not much I can do I imagine? Besides having the ECU flashed and I wouldn’t know where to start with that. Or would the bike adjust as much as it can?
 
My thinking is perhaps the motor is running even leaner than stock because of the exhaust. On my former 700X the best I ever got (per Imperial) is a little over 80mpg. On my 750 I average around 73.

On the Imperial/US gallon subject Y'all can assume that if a member from the UK or in my case Ireland are talking MPG it will always be Imperial.
Not sure I like the idea of running that lean. Not much I can do I imagine? Besides having the ECU flashed and I wouldn’t know where to start with that. Or would the bike adjust as much as it can?
I don’t think you’re running overly lean. As I said earlier, you 90.1 is about what my average is over the past 58,000 miles on an all stock 670cc engine/exhaust. My personal high record for a tank of gas is 113.5 mpg Imperial.

If your oxygen sensor is still in place and the EFI is running closed loop, I would think you’ll be fine. If not in closed loop, I think the default mapping will run it even richer, based on my experience with a different model Honda.
 
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