2 questions

[Kratzer]

1981 GS 850 GLX

Why am I only getting about 25 MPG?

What should my RPM's be while cruising along at about 55 on the highway in 5th? Becaue yeah, I am at like 5000 apprx.

Normal things, or do I have a stuck brake or something?

[Dogma]

Well, something is wrong. I got about 43 mpg on mine last year, with only moderate goofing off. I can't wait to see what I get this year after sealing the intake system up. Unfortunately, I can't remember what revs you should have at 55. I can't give a good answer anyway, because my speedo is wrong by at least 10 at that speed.

Is it running well, or is there a chance it's super rich or some other problem?
When you goose it, does it feel like the clutch is slipping?
Have the brakes ever been rebuilt?

[Kratzer]

Im not exactly sure on the MPG, but it seems low.

As far as it running right, its not. But I am chalking it up to the cold cold air being denser than summer air- making the mix funny.

My brother has a 2002 bandit, and he said his is doing like 4400 at 55 mph. I know its kind of an apples to oranges deal, but just curious whats up.

I haven't rebuilt the cailipers. Is that hard?

[seuadr]

nah most of the regular mantinence items on gs's are pretty simple. the most important thing is, when you replace the cup, make sure to tighten it in evenly, i like to use a "C" clamp placed right in the middle of the cup.

[Kratzer]

Ok-

It doesn't seem like the clutch is slipping, but any tests I can try other than "feel" of it.

[Nessism]

Is the bike stock or modified?

[BassCliff]

Hi Mr. Kratzer,

Normally, your 850 should get 14 mph per 1000 rpm in top gear. For example, 5000 rpm should get you 70 mph, 6000 rpm should get you 84 mph. Your speedo might be off. They usually read a little low, but 15 mph low?

As for mileage, I've gotten anywhere between 31.5 mpg and 39.5 mpg depending on how long, how hard, etc.

Thank you for your indulgence,

BassCliff

[Clone]

That is low MPG, even for an 850. I would start with the air cleaner, then work my way towards the motor, air cleaner-petcock-carbs-plugs-valves.
Apparently you have changed something or modified something, or something has modified itself. You should be getting better milage than that. In the high 30s to low 50s. There is about a 15MPG range in there that your bike should operate in grannying it along or floggin' it down the road.

[chef1366]

Spin your rims to see if they are hanging up.
My bet is carb related. Do your plugs read rich?

[Kratzer]

The plugs read pretty good.

As far as the carbs, there is some problem there. Basically when the bike is cold, and its cold outside- under 40 F- the bike hangs up at like 3500 RPM, then it shoots like an arrow. My guess on that is my main jets are fine, but my secondaries are a little plugged. So my remedy is seafoam- I loaded the tank with some seafoam, and every time I have taken the bike out, it gets better. I think the seafoam is doing its magic. By the time the bike warms up, its about 90% smooth on the acceleration.

But as far as the plan of action, I think I will be doing the following:
1A. Strap GPS on to handlebars- check speedo.
1. Sealing my airbox
2. spinning my rims to see if there is a hangup
3A If a hangup, rebuilding my calipers
3B. changing plugs

[Steve]

But as far as the plan of action, I think I will be doing the following:
1A. Strap GPS on to handlebars- check speedo.
1. Sealing my airbox
2. spinning my rims to see if there is a hangup
3A If a hangup, rebuilding my calipers
3B. changing plugs

All good items.
1A. I think you will find that BassCliff had the right idea, but went in the wrong direction.
Most speedos read a bit high, that is, when the speedo reads 60 mph, your GPS will likely read about 57 or so, depending on the front tire size. If you are running the stock 90/90-19, that will be true. If you have a 100/90-19, it will be so close to right that it might scare you.
1. Always a good idea. BassCliff has a nice tutorial on his website that deals with that.
2. Be aware that spinning the rear wheel is going to have some drag, even if the caliper is removed, due to the shaft drive. You should still be able to move it easily, but it will stop within about half a revolution if you try to spin it.
3A. 'Rebuild' with new seals (they're relataively cheap) if you want, but the calipers might just need cleaning. To clean them, remove the caliper from its mount, slowly operate the brake to force the pistons toward each other. Watch them to make sure they are both moving, not just one. One piston will pop out with hydraulic pressure, you can remove the other one carefully with channel-lock pliers. Clean the outer surfaces with Scotch-brite pads to remove built-up dirt and corrosion. Carefully pick the seals out of the piston bores. There is a narrow dust seal and a wider fluid seal in each bore. Wipe the seals with a clean rag. Use a pick to clean the grooves very well, and wipe out the rest of the bore, inspecting for roughness. Lubricate the seals with fresh brake fluid and re-install them. Put everything back together with new pads, and be sure to flush the fluid throughh to have fresh fluid throughout the entire system, too.
3B. Not a bad idea, but check the color on the plugs you have in there, too. If they are a nice tan color, that's good, so check the wear.

.

[Nessism]

I'd still be interested in knowing if the bike is stock or does it have a modified exhaust/intake where someone installed larger than stock jets.

[tkent02]

Sounds like you are too lean while on the needle, perhaps the fuel levels are a little bit low?

Check also the ignition timing, people set them incorrectly quite often.

Both will effect fuel mileage.

[Kratzer]

Nessism- I have a V and H 4-1 that was installed by a bike shop. All I know is that they charged the PO was charged 600 for the job- I have the reciept, so I assume, but do not know they were rejetted.

How do I check my timing or even adjust it?

[tkent02]

Nessism- I have a V and H 4-1 that was installed by a bike shop. All I know is that they charged the PO was charged 600 for the job- I have the reciept, so I assume, but do not know they were rejetted.

How do I check my timing or even adjust it?

Pull a float bowl off and see what main jets are in it. Then you will know.

Timing, download a free manual from Basscliff's site.