Starter Valves Sync, Valve Clearances and Fuel Economy

[dduelin]

The starter valves richen the fuel/air mixture for cold starts and have no effect on fuel/air mixture above off-idle rpm. If you look at the tiny starter valve passages that allow air flow when the butterflies are closed compared to the intakes when the butterflies open you see why. Honda's Programmed Fuel Injection system controls fuel/air mixture in the ECU based on sensor inputs from coolant temp, O2 in the exhaust, and intake tract air pressure.

 

[Dobby]

Filling up on the side stand, means a little bit less fuel than if you were on the Center Stand, filling up to the same mark. However, if your riding is at an average speed of 85 km/hr or 51 mph and if in the 5th gear. You should get some great gas mileage. 85 km/hr is about the sweet spot for a rebel 250. That engine loves 50 mph. I had a nighthawk 250, so that is how I know. There does not seem to be anything wrong with your bike.

Here is my 0.1c. Fill up your tank the way you normally do and go on a 450 km solo trip (225 km each way), possibly on the highway (to eliminate variables of stop and go and variation in speeds) and see where the flashing bar comes on. Maintain an indicated speed of 115 km/hr. You should be able to get close to 450 km.

One of my friends live exactly 210 kms away door to door, I guess it's time for a visit. Without stop and go traffic and maintaining a constant 115 kmh, I would expect even better mileage. The Roads we typically ride have a 80 KMH speed Limit anyway, but yeah, the wife's Rebel 300 kinda likes that speed. Anything more and she complains that it gets a little too buzzy. Meanwhile, My ST is gliding in 5th and I barely know the engine is running. It's just a bit confusing since nothing has changed except for the addition of a slightly larger windshield, yet I am down a whopping 80 KMS per tank. I am not sure if this means anything but when my last bar starts flashing, I fill up with 22.5 to 23 Liters. Always around the same amount. I understand it is a 29 liter Tank, so shouldn't it take a bit more?

 

[Dobby]

The starter valves richen the fuel/air mixture for cold starts and have no effect on fuel/air mixture above off-idle rpm. If you look at the tiny starter valve passages that allow air flow when the butterflies are closed compared to the intakes when the butterflies open you see why. Honda's Programmed Fuel Injection system controls fuel/air mixture in the ECU based on sensor inputs from coolant temp, O2 in the exhaust, and intake tract air pressure.

In that case, it could be any one of those sensors causing my fuel efficiency problem. I might be misunderstanding, but since the starter valves have no effect off idle, is it still worth synching them?

 

[Dobby]

Random thought, has Canada increased any non Dino base fuel to the gas pumps?

I wasn't aware that was a thing or whether there are any plans for that. Whatever it is, we are paying way too much for it. Last night I filled up at $2.10 per liter for 93 Octane. Regular was $1.80 per Liter. Robbery!!!!