Hi! The last visit to the fuel station was to me terrify- for a 170km ride need my bike 17,5 L fuel... I ride 10km everyday to work with moderate speed , and sometimes to the nearby town to shopping...On the bike seems everything OK, the hole of exhaust pipe is grey... The air filter is a little old, but looks like clean...What can i more checking for lower consumption?

That high consumption.......and a grey outlet........makes no sense to me.
You then should have a black outlet..........or do you go verrrry high speed, Bazi?

Hole in the tank ...........or special counters at the fuel pumps in your country.

That is the double compared to what I use............but we got low speed limits in Norway.

I go +/- 20 kms on a litre of premium. This average out to about +/- 5 litres per hundred kilometres, and I give it some stick regularly. A compression test will isolate a few things like low compression due to worn rings or too-tight valve clearances, but a more detailed leakdown test will tell if it's the top end like excessively worn guides/valve issues. The ignition timing is also a good thing to verify. There are many threads about just how to go about performing that task here, too.

Was this fuel mileage loss a sudden occurrence or gradual?

Good luck and let us know how you go.

when we ride together with my friend owning a k100rt, we always put the exact same amount of fuel in our bike. The average is 7.0L/100kms. My brother consumption on its RT is exactly the same too. The RS seems to be more economical to run.

Increase of gas consumption could be related to a bad fuel pressure regulator.
The FI computer calculates the amount of fuel to be injected by assuming that the fuel pressure is at 36psi. To inject the right amount, it calculates the time that the injectors have to open. If the gas pressure increases, the amount of fuel injected will increase too.

2 days ago, I posted a cheap way to check the FPR (Check it here)

CF

Crazy Frog wrote:when we ride together with my friend owning a k100rt, we always put the exact same amount of fuel in our bike. The average is 7.0L/100kms. My brother consumption on its RT is exactly the same too. The RS seems to be more economical to run.

Increase of gas consumption could be related to a bad fuel pressure regulator.
The FI computer calculates the amount of fuel to be injected by assuming that the fuel pressure is at 36psi. To inject the right amount, it calculates the time that the injectors have to open. If the gas pressure increases, the amount of fuel injected will increase too.

2 days ago, I posted a cheap way to check the FPR (Check it here)

CF

It comes a loud buzzing sound out from my fuel tank, you gave me a good advice... Also i must lose the rubber tube and pump it with the exact pressure.. And then? What must i see/heard?

Bazsimoci wrote:
It comes a loud buzzing sound out from my fuel tank, you gave me a good advice... Also i must lose the rubber tube and pump it with the exact pressure.. And then? What must i see/heard?

If the pressure regulator is working correctly,when you get to 36psi, the FPR will open and the pressure will drop.
If it fails, you may have to apply more pressure.

CF

OK I had checked the Clymer Manual too, and i understand now! Many THX!