Fuel consumption: my friend his FI is much more economical

Hello VFR enthusiasts,

I gifted myself a '99 FI last fall, which was supposed to serve as a commuter bike. But he has proven himself to be so much more: I secretly fell quite in love with that charming red one. And that while I ride in all kinds of new bikes as a motorcycle journalist. I think that says enough.

Anyway: I don't get further than 1 liter on 15km (1:15), while I'm not driving abnormally or anything. The fuel light starts flashing around 250km. And yes, now I can already hear you shouting: all 98 and 99'ers do that. I know that. And also that the 2000 version is more economical. But here's the thing: I recently got in touch with a guy in the neighborhood who also owns a '99 who's already racked up nearly a ton. He easily does 1:19. So it is possible. In the beginning his also did around 1:15. But after he had tried everything like new air filter, new spark plugs, synchronization and you name it, he threw in a bottle of Eurol injection cleaner. Then he suddenly ran 1:19.

Now mine has done 44,000km and I took good care of it when I bought him: synchronization, coolant, engine oil and you name it. And also injection cleaner. I will try this again and also replace the air filter. Maybe i'll try checking the valve clearance.

My question to you guys: in which direction would you look and are there perhaps similar experiences? Thanks in advance.

 

My last 99 (owned between 76000 and 103000km) would make around 280km before the last bar started flashing. My new 99 (78000 km) happily gets to 320km, and I cannot explain that difference. Both were well-maintained, and the earlier bike had a refreshed fuel pressure regulator fitted but no difference. I don't think I'm riding any differently on the new bike.

I would suggest looking more widely, maybe dragging brakes?

 

has your temp gauge gotten to or above half-scale ? if not, you might have a bad thermostat that doesn't let the engine reach best operating temp, which wastes fuel.

it's not a quick job to change a thermostat on a FI bike..........but i can do it in about 10 minutes on my '86 VFR 700. progress ???????

 

It's not that hard and how often does it really have to happen, not very.

 

Both of my 5th gens have needed a new thermostat. I'm yet to change the thermostat on my current bike (presumably it is on a slow boat from Japan) and it runs at a temperature in accordance with airflow, a big tailwind makes it a bit hotter (up to 88C), a decent head wind makes it run cooler (72C). And yet...it is noticeably more economical that my first one, which had extremely consistent running temperatures and fast warm-up.

 

I’ve read the thread on it. It sounds pretty hard to do on this bike. I know I need one and think I’ll support my local shop for the job.

 

The issue with the thermostat is not that it is especially hard to do but it you do need to take lots of parts off. When you get under the throttle bodies the thermostat housing just has two 8mm bolts and an o-ring, but to get in there...

So if you pay a shop to do it (and I do understand that it is good to keep them in business) you will mainly be paying for the time taken to strip the side fairings and tank, to drain and refill the cooling system, and to disassemble the airbox and loosen off the throttle bodies. I'm guessing they will charge for 6 or more hours labour, plus $100 parts.

I just replaced the thermostat on my 2005 ST1300, I only had to pull off the side and lower fairings and remove the radiator on that one, still took a couple of hours though.

 

I kind of fixed this issue. I used two bottles of fuel injector cleaner (over a time of 2 months) and I can easily reach 320km on a tank now. I'm happy.

 

I had the fuel injectors cleaned by a local specialist when I replaced the thermostat. I did destroy the little injector orings while re-installing and had to order a 2nd set.