Sudden change in gas mileage

[Delasangre]

So recently maybe 2-3 weeks ago my gas mileage suddenly plummeted. I was getting 35-36 MPG US on my commute and 40-47 highway depending on the speeds. Bike just turned 12000 miles and it's a 2016.

Now I suddenly get 32 on my commute and I just did 400 miles on the freeway at 35.

A year ago I did a road trip and averaged 47 MPG riding fairly hard for part of it. This trip I did 165 miles and pulled into a gas station with 9 miles of range. Put 4.95 gallons in. So I'm doing 33-34 MPG. Cruise control on the freeway at 70-75MPH.

The only thing I've recently changed was to put a new front tire on and a manual cam chain tensioner, neither of those seem like the sort of thing to ruin fuel mileage. In fact with the chain tensioner it's running smoother than ever.

So far it's been suggested that my air filter is plugged, my injectors are gummed up, or I need a valve adjustment. Any ideas would be helpful.

[wessie]

when was the last service? 12,000 miles is a service interval unless you have done them by the calendar.

[Delasangre]

Originally Posted by wessie

when was the last service? 12,000 miles is a service interval unless you have done them by the calendar.

I did a service at the dealer at 7000 miles roughly but then I changed the oil about 6 months ago at about 11000 miles when I resealed my oil pan at home so I'm not exactly on the exact schedule any more. But ya it has been about 5000 miles through a wet winter and spring since my last air filter.

[wessie]

Originally Posted by Delasangre

I did a service at the dealer at 7000 miles roughly but then I changed the oil about 6 months ago at about 11000 miles when I resealed my oil pan at home so I'm not exactly on the exact schedule any more. But ya it has been about 5000 miles through a wet winter and spring since my last air filter.

then you know what you should be doing...

I would invest the $$$ in a dealer service as they will be able to read any fault codes and address them accordingly. They will also apply any software patches and reset any out of spec parameters in the fuel system.

[Delasangre]

Originally Posted by wessie

then you know what you should be doing...

I would invest the $$$ in a dealer service as they will be able to read any fault codes and address them accordingly. They will also apply any software patches and reset any out of spec parameters in the fuel system.

Isn't that something I can do with the GS911 tool?

[wessie]

Originally Posted by Delasangre

Isn't that something I can do with the GS911 tool?

some of it, yes. Software patches, no.

[smithy]

Originally Posted by wessie

then you know what you should be doing...

I would invest the $$$ in a dealer service as they will be able to read any fault codes and address them accordingly. They will also apply any software patches and reset any out of spec parameters in the fuel system.

Umm...there are no software patches for a '16 Euro-3 model available that I'm aware of.

Smithy.

[Delasangre]

Originally Posted by smithy

Umm...there are no software patches for a '16 Euro-3 model available that I'm aware of.

Smithy.

I'm a US model and I don't see how a software patch would cause my to suddenly loose 10% of my fuel mileage overnight.

[smithy]

Originally Posted by Delasangre

I'm a US model and I don't see how a software patch would cause my to suddenly loose 10% of my fuel mileage overnight.

They're all pretty much the same whether US/Europe/Aussie models. A diagnostic session on a GS-911 may shed some light. 10% fuel economy loss is indeed significant. My '17 Euro-4 averages 4.8L/100km or about 49mpg (US-gal)....about 59MPG (UK Imperial-gal)....unless I'm getting up it.

Smithy.

[Salem]

I'd check simple things first. The engine is not going to run rich because of a clogged filter, the O2 sensors control that. It might run less efficiently though. But is tire pressure ok, and the chain typically is starting to go bad  at 12k mls. I just tried this: Spin the wheel in neutral, starting with a marker on top. You should be able to give it a good 180 swing, thus marker on bottom upon release.  Mine then rotates almost a full turn more. That's inside with cold engine, 20C