Honda ST1300 Section > Fuel & Additives ST1300

Excessive Fuel Consumption, Any ideas?

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zevk:
Hi guys,

My fuel consumption is pathetic, 13 km p/litre!
I've had the 2006 ST1300, for the past 2 months.
It has 49k on the clock and had a major service at 42k. It is in magnificent condition, as new.
The bike is smooth and the plugs are fresh, dry and not fouled with rich appearance.
The bike has stock mufflers, intact and no engine, power-commander mods.
The air filter was replaced (Honda OEM) at 34k (8k ago) and appears to be pretty clean.
Regardless I will order a new air filter (hi-Flow from ebay ok? don't like reusable K+N much and dealer wants $90 for oem)

I wonder if I may have a "pair" or other vaccum leak? Problem is the screws that attach the airbox to the throttle bodies are seized, despite my purchase of a JIS impact driver.... my next otion is to drill grabbit extractors and hope I can remove those soft screws... ughh not looking foward to that job...

any further ideas would be appreciated.

thanks

Zev
 :13Candy :13Candy 

Breharna:
Zev, not an easy question to answer as there are so many factors to think about when measuring fuel consumption, traffic conditions and riding styles (hard/easy) really weigh into the equation.

So ignoring all that, the dealer would have or should also negate vacuum leaks when they did the major service at 42K's.  It would be obvious if they put vacuum gauges on your throttle bodies to check or synch them at that service.  Also a vacuum leak is USUALLY pretty obvious as it tends to give an irratic/varying idle.

Again if the dealer did the service correctly and its had this consumption issue since you had it, you may have to live with it, especially with the condition you detail about the bike and more importantly the condition of your plugs.  If the colour is good on them and they are the correct plugs, then there is  NO issues with mixtures or ECU issues.

However, there are a couple of little things to consider.  Fuel computers on bikes and cars are fairly optimistic.  There is usually a built in tolerance of up to 10%   The other main thing I would check is your speedo accuracy with a Sat Nav.  Just as a guide, I have seen bike speedo out up to 20% on some of my customers bikes.  This would only give a poor fuel consumption figure if your speedo was reading slower than the Sat Nav.  Your odometer reading is calculated along with fuel used/measured by your ECU (Fuelside) to give you the avereage fuel consumption.

If your speedo reading is okay, then the only thing I would do in the meantime is, fill your tank, reset your trip odometer and when you get low on fuel refuel it and check how many kms you did for the fuel used, just to see if the bike computer is giving shit/incorrect readings read outs.

If your actual fuel usage is OK with KMs travelled and its a wrong reading, just switch off that side of the display, same way you can change the readings from l/100kms and kms/l

I just read this over, and if I go on any more I'll confuse even me.

If your not happy with the consumption after all that, give me a call after New Year and I can have a look at it for you.

zevk:
Stewie thanks for the info and reply.... I used to be a Honda m/c mechanic many moons ago and agree completly with your analysis.

I calculated the actual kms per usage / litre (not based on the bike computor) and came up with simmiar high fuel consumption avrg 13 kms p/litre using 95 and 98 octane caltex fuel.

I may have to drill and e-z-out / grabbit the siezed screws that secure the air box housing to throttle body and hunt for air leaks, but I would be surprised, as the engine starts/idles/revs smoothly through the powerband at all temps and conditions.

will try replacing the air filter as a start as not looking foward to removing siezed screws, I HATE broken studs with a passion...

thanks again

Zev
   

Brock:
Before any drilling takes place, or any alterations are done, Go for a ride out of town to some place you can ride at a constant 110 Ks per Hour. Top up the tank, and go for a long ride out for 200 or so Ks, tun around and go back and fill up again. this will give you a good base line fuel consumption.

Just to give you an example, my worst consumption is 14.5 Ks per L to and from work, with a bit of wrist twisting. Its a mix of country and town riding. Best consumption this year is 19.0 Ks per l on a 322K ride om majorish roads at around 110Ks.

What conditions are the major use of your bike used in, city stop start or open road. What fuel are you using??

saaz:
ST13 does not have any pair system.  Are any codes being thrown on the dash?  If it was a car I would suspect something to do with the oxygen sensors, or a connection to them. Has the bike always had this problem since you bought it?  If you are only getting 13 km/lt usually you would be in jail by now as it would take a really heavy throttle hand to get that.  I might also suspect that the idle circuit is staying on, causing rich running.  A malfunctioning temperature sensor might also cause it to run rich all the time.

As the ST13 is an EFI engine, the basics of oxygen sensor/engine temperature sensor/air sensor (MAP/MAF) are the main items to look for.   Blocked exhausts/cat converters would be a rare thing.

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