Fuel consumption?

[Big T]

Strange... so you're saying that the spark advancers that can be bought do nothing?

I'll install mine when I have the chance, and report on any percieved changes.

Daniel,

That's pretty much the case for spark advancers, minimal power improvement. Especially with an older design like yours (ours).

Even a new bike, like an R!, only picks up 2-3HP with one. Race bikes, that's different.

[dardoonk]

Junkie, you say you've noticed the problem over the past few tanks of fuel.. Is that because you had never checked it, or had you checked it before and it used to be better? I assume you've been making this 80mph run for awhile, but maybe try a couple tanks at 60mph and see how much difference it makes.

If you know you used to get better mpg, and this is a recent occurance, then my next point might be moot, but... are you sure your jetting is correct? Your main jet & pilot might be spot on, but how far open is the throttle during much of your run? Say, for example, your holding it 1/2 open for much of the run, but your needle e-clip had been lowered (richening the mixture) at some point, then it could be your pouring more gas in than you need to be.

Let us know what you jetting is, including the clip position if you know it. The carb guru's here will take over... and BAM... you have a bunch of work to do!!

[Junkie]

I haven't had the bike for all that long, I got it at the beginning of January. I hadn't been paying attention to gas mileage before, but I think it was about the same.


I also haven't checked the jetting or anything, the only things I've done are an oil change and valve adjustment.

[82Shafty]

Does anyone have a motorcycle article they could scan showing that advancing timing and using premium is pretty much a waste of money?

Again, I can't necessarily speak for the inline four world, but it's has been dyno proven time and time again that on a 5L ford with base timing set at 10 set from Ford; by advancing to 14-16 base usually picks up an honest 5 rwhp for a total of 34 degrees advance.

I suppose it may be relative, but on a 205 bhp engine, it netted a 3.5% gain so I suppose figure a 3% gain from your starting point.

I.E an 1100G with 98 hp, figure about 2-3 hp. Base and total are two different measurements and then you get into advance curves.

I would certainly believe that at 85 it may be a bit hard to achieve the mpg that you're looking for; maybe you should look into an 08 250 sport bike that gets 70mpg; but I doubt it's 70 mpg at 85 mpg... probably measured at 55 mph.

[Kcwiro]

any smell of fuel when the bike sits all night? on cold start up is there a white fuel cloud when it first fires up? leaking float needle into the engine symptom. they don't always leave a puddle.
does the engine oil smell like fuel?

air filter type? is it clean? ignition timing at proper setting?

I had vm26 that got the worst mileage 26 mpg and switched to rs 34 cv carbs and my mileage jumped to 45mpg. all problems went away with the old carbs..

yep after a 75 mile tank full of fuel and we ran out on an old country road I changed those carbs.

Umm the white smoke thing...if the bike sits overnight wouldn't that usually be just condensation that settles in the pipes? I'm no carb genious but I always dismiss the cloud since it generally goes away once I warm the bike up...would like to know certainly if I am possibly doing damage unknowingly. Gas mileage for me on 750 is about 44

[twistedwankel]

I've been getting pretty horrible gas mileage on my '85 GS700 (very similar to the GSX750 everywhere but the US) recently. The past couple tanks have been right around 30mpg even.Ideas?

thanks

Up the hill I get 25 mpg and down the hill I get 25mpg. Around the corner I get 100mpg going in and 20mpg going out. I get 50 mpg on the very center of my tyres at 60mph and 50mpg on the sides of my tires at 60mph. Therefore: If you stay on either the center or the sides of your tyres you will get 50mpg but if you go up and down hills you will only get 30mpg as you are going 60mph up the hill and 100mph down the hill. This is known as the "Suzuki Effect":-D

My properly tuned 750 is getting 48+mpg while riding in a normal fashion and trying to keep up with an 1150 that is 22 years newer

[Greg O.]

According to what my 750 does, you probably are not too far off. Cruising at 70 to 75 I get 33mpg. If I slow down to 60mph it goes up to 45mpg. MPG really drops off as I approach 70mph.

Greg O