Super Low MPG

[Gorminrider]

It sounds to me that the bike is running pretty well. I don't have any reason to doubt your carb guy . You'd hope he'd notice irregularities from his own experience with the bikes. I've never seen huge results from any tweaking of mixture screws beyond the hope of a really smooth and clean idle. But then, I'm not so much at idle- a maximum of 6 stoplights in town and they're never all red... I've mentioned floatlevels and a stuck choke/enricher soo, I'll harp a little more on the calculation?

"As far as math - are y'all talking about the mpg math..I just put in how much I bought and my current mileage.

" Yes, mpg...Of course, and that should work fine. Need note however to confirm that the usual technique requires you to fill the tank each time... Then, with this baseline( a full tank) you can quickly check per
(A-B)/G=mpg
where A= latest odometer at fill-up
B=previous odometer at previous fill-up
G = latest gals to fillup...
(A-B) is therefore the miles travelled between fillups. Divide this by G (gas replaced to bring back to baseline= gas used per the miles it took the bike) and you get the correct result. I use the bottom of the filler neck in the tank and try to get very close to this each time.

PARTIAL fillups to no known "baseline" will give the wrong result*

...As an aside, this really is telling you about the previous fillup per quality of gasoline (I note the brand and type of gas) and terrain (mountains, or city, or prairie highway ) These will likely show up as different "averages".
Even periods where gasoline evaporates or leaks can show up in the results.

It might be convenient to add columns in your spreadsheet to note oil changes and maintenance notes too- it's handy if you're not doing it elsewhere.

* another method is an empty tank, pour in a the same quantity of gas each time and ride the bike until it stops-not practical or safe though.

 

[jimhickcox]

Because it's the easiest thing to get at and test I'm doing my fuel screws this afternoon. We'll see how that changes things.

Nessism - I haven't gone into the valves. I've always doing oil and basic maintenance but I'm still pretty new at really pulling things open, and like I (think) I said, this bike is my daily (I don't have a car). So while it's running well I'm trying not to create extra downtime. I'll get in there when I have a weekend and don't have to go anywhere though.

Steve - When I spray-clean, I pull the carbs, remove everything I know how to take off and soak all that in cleaner, spray out the inside surfaces a few times, and then reassemble. I know it's not ideal, but it's not a total waste of time and money because my needles were sticky and the bike was dribbling fuel, but now it's not. Also I'm not sure how much of the can I use, but I've done this at least three times to different bikes and I'm still on the same can. So not a ton?

I always feel like I'm mistreating the engine if I'm driving around at less than 3k - is that not lugging it a little? Maybe it's because I was riding a 550 daily for the last couple of years? That guy doesn't even start to pull until ~4k. But on that, a 550t with pods and no second gear, riding roughly the same way, I still averaged 33.41mpg over the last 5000 miles, which I feel like I ought to beat with my stock airbox and exhaust setup on this (and all of the gears).

mattd1205 - I checked for leaks and had some in the boots on both sides of my carbs, so I replaced them and they're good now.

Rob S - Where do I mail the payment check?

Gorminrider - Yeah, I asked him (my guy) about the mpg and he said everything was running well and he wouldn't know what to change. I do suspect it will benefit me to do a full teardown on the carbs when I can, and replace the gaskets and stuff. As far as the mileage, I'm pretty obsessive about how I'm filling the tank. I don't take notes on vendor/quality, but I do note when and various other things, and calculate miles per day, miles per gallon, and the day and mileage at which I do every service, so I can see what affects what and how.

 

[Steve]

I haven't gone into the valves. I've always doing oil and basic maintenance but I'm still pretty new at really pulling things open, ...

I'm sorry, but if you have not "gone into the valves", you have NOT been doing "basic maintenance".

I always feel like I'm mistreating the engine if I'm driving around at less than 3k - is that not lugging it a little? Maybe it's because I was riding a 550 daily for the last couple of years? That guy doesn't even start to pull until ~4k. But on that, a 550t with pods and no second gear, riding roughly the same way, I still averaged 33.41mpg over the last 5000 miles, which I feel like I ought to beat with my stock airbox and exhaust setup on this (and all of the gears).

Many years ago, I was taught that "lugging" an engine is when you can not accelerate while using the current gear. At lower engine speeds, you will also notice some chugging and bucking along with the lack of acceleration.

Yes, a 550 is notoriously low on power, especially below 4-5k. The fun on those is definitely above 6k.

If you averaged 33 mpg on a 550, you might want to check into calibrating the nut that holds the handlebars. :-k
A 550 should regularly return over 50 mpg. If you flog it constantly, it will dip into the 40s, but 33???

.

 

[rphillips]

Plug readings haven't been mentioned lately, unless I missed it. With the mpg. you're getting, your plugs should be black, wet & almost dripping fuel. If your plugs look OK, paper sack color, I'd look for gas getting out somewhere else, possibly overflow tubes, fuel line leak or something. When you're cleaning your carbs with aerosol cleaner, look close all inside the carbs, there are tiny holes in there. With the little straw on the spray tip, hold the straw on these little holes, sometimes ain't easy, but squirting cleaner in any hole, you should find cleaner squirting out the other end of that hole. none of the holes are dead end, every hole you squirt cleaner in, you should see the cleaner squirting out. I just don't see if your plugs look good, that much fuel can be going thru the cylinders. Just my opinion.

 

[Nessism]

Failing to adjust the valves will damage the engine; the clearance reduces with mileage and eventually the valves don't close so they burn, along with the seats. Shame on you. Hopefully the engine isn't damaged already.

 

[rphillips]

Yep, what he said about the valve adjust. It ain't hard, but it will do major damage if they are too tight, I have a CB1100 head out in the shop with 2 "burnt" valves, just cause I neglected checking them.

 

[Rob S.]

If you averaged 33 mpg on a 550, you might want to check into calibrating the nut that holds the handlebars. :-k
.

I'd appreciate if you'd call me Mister Nut.

 

[Steve]

I'd appreciate if you'd call me Mister Nut.

I have other names for you. :-\\\

That comment was addressed to the original poster, jimhickcox.

.

 

[jimhickcox]

Steve - The valves aren't due for an adjustment for another thousand miles (per the service manual and records). I'll get in there when it's time, and maybe before if I have the free time, but right now up-time is more crucial than cleaning up my MPG. And the 550 has seen some things - it's been a beater for a while, and it's jetted up to compensate for the pods someone put on it, but even Suzuki only specc'd it at 42mpg new, so mid-thirties on a guy who's had a rough life seems like an okay kind of low. Especially in the kind of traffic I ride in.

Nessism - I'll check the valves when they're due, don't worry. I'm not trying to ride this bike into the ground so soon after buying it.

Rphillips - Yeah, my insulator tips are pretty black all the way down, like you'd expect on a plug on a bike running real rich. Hopefully my misunderstanding about where the fuel screw should be at was the big issue and will get me back up where I want to be.

 

[Nessism]

How do you know when the valves were last adjusted? Do you have service records from the previous owner?

 

[GSXR7ED]

How do you know when the valves were last adjusted? Do you have service records from the previous owner?

Good point! I did my own and posted it in one of my threads.

Lots of interactions going on in this thread. Do's and Don'ts are always fun to read.

Ed

 

[jimhickcox]

How do you know when the valves were last adjusted? Do you have service records from the previous owner?

Yeah. Is there another way to know?

 

[jimhickcox]

FYI I'm at a half turn on my fuel screws right now and it's still driving the same, although it's idling slightly lower.

 

[Steve]

What's the setting on the air screws?

.

 

[jimhickcox]

What's the setting on the air screws?

One and a half.

 

[cowboyup3371]

Yeah. Is there another way to know?

Remove the valve cover and check it yourself now - will only take a few minutes to check and a few days to get shims and a gasket if you need to adjust any of them

 

[allojohn]

Yeah. Is there another way to know?

Have you considered the PO may have adjusted the valves badly? The only way to know is to check them yourself. Do it and eliminate the valves are the problem. If not, everything else you do to fix your MPG issue will be in doubt..

 

[GSXR7ED]

Have you considered the PO may have adjusted the valves badly? The only way to know is to check them yourself. Do it and eliminate the valves are the problem. If not, everything else you do to fix your MPG issue will be in doubt..

Process of elimination...good idea!

Ed

 

[Nessism]

No disrespect to Mr. jimhickcox but threads like this typically follow the following theme: the brethren here at GSR offer possible ideas for the root cause of the issue and the OP (original poster) shoots them all down. Simple matter of act is that a bone stock 1st gen GS750 should be able to fairly easily average 40+mpg if everything is up to snuff on the machine. If the bike is not able to match this it's time to dig into routine maintenance first and troubleshooting secondly. Compression, spark, fuel. Go back to basics until the problem is solved.

 

[GSXR7ED]

Totally agree with nessism on the PM (Preventative Maintenance).

As for the dialogue, well that happens. Lots of personalities on here so smart-alecs abound...lol.

Ed