Gas Mileage

[djscottymiami]

I've got a 1980 GS850. The last tank of fuel I had in her, even tho there was a lot of idling and testing (because of my charging problems) she did 10mpg give or take :shock:


I filled it up, went on a little 30km trip to the lake out here and came back. Did a little bit of driving around town. I've got maybe 100km on this tank now (60miles ish) and it's down to almost half a tank of fuel.


What can I check to improve the mileage? I don't think it should be this low. One thing I know for sure is that the valves have probably never been checked (with 50,000km on it) and that the carbs probably haven't been touched either.

Any tips for a bike newbie?

[DanTheMan]

Which 850 is it? A "G" or "L" model? Normally on my "L", after 60 U.S. miles I'm around 1/2 tank depending on wind and throttle conditions. If I ride sixty miles doing 75 mph I only get about 100-110 miles from my "peanut" tear drop 3.6 gal (US) tank.

[tkent02]

You guys need to learn to make things run correctly.
Valves, carbs, all the other little things left neglected cost you wasted gas.

[djscottymiami]

Which 850 is it? A "G" or "L" model? Normally on my "L", after 60 U.S. miles I'm around 1/2 tank depending on wind and throttle conditions. If I ride sixty miles doing 75 mph I only get about 100-110 miles from my "peanut" tear drop 3.6 gal (US) tank.

My registration says its a GS850GL .. and I believe we do have the same sized tank since 9L of fuel brought me from a little over a quarter tank to full. Makes me feel a wee bit better now knowing im not the only one with this problem lol. The P.O told me the tank on this one was small. I just dont think I believed him.


tkent02: Adjusting the valves is on my list of things to do later this summer... riding season up here is short so I want to get as much riding in as I can, and do maintenance at the end of the year hopefully.

[flyingace]

A good-running 850 should deliver a minimun of 35 mpg. During my last trip, fillups would indicate around 50 mpg (I'm a very sedate rider). If I push harder, it will go into mid to lower 40s. Your tank will seem a lot bigger if you pull this kind of mileage.

Is the bike stock? If different pods and/or exhausts have been put on, mileage typically drops. Check you spark plugs for over-rich mixture. Check your compression. Does the bike roll easily in neutral?

[DanTheMan]

On edit: from my last post, I meant that if I'm running 70-75 mph I only get about 100-110 miles on my tank. that equates to about 38-41 mpg, and it's quite normal for an 850. When I do my valve shims I expect better mileag, but I've way too many irons in the fire right now to do that job. It might happen in the next 5 weeks though.

[mf70]

... Does the bike roll easily in neutral?

Boy that brought memories back. After years, crud had accumulated in the brake cylinder. Since it was a slowly progressing drag, I never noticed it building up; I just thought the bike was hard to push. A front brake rebuild increased performance by 30%!

[DanTheMan]

I somehow interjected the sixty miles in that sentence....that part should have been omitted....

You guys need to learn to make things run correctly.
Valves, carbs, all the other little things left neglected cost you wasted gas.

[djscottymiami]

A good-running 850 should deliver a minimun of 35 mpg. During my last trip, fillups would indicate around 50 mpg (I'm a very sedate rider). If I push harder, it will go into mid to lower 40s. Your tank will seem a lot bigger if you pull this kind of mileage.

Is the bike stock? If different pods and/or exhausts have been put on, mileage typically drops. Check you spark plugs for over-rich mixture. Check your compression. Does the bike roll easily in neutral?

Exhaust is a contraption the P.O put onto it so that it would pass safety. It had no exhaust when he got it so he had to fab somethign up. It does have a few holes in it though.

Is there a guide for the spark plugs for the mixture? Im quite new at all this.

The bike does seem to roll easily in neutral. This is my first bike so I dont really have anything to compare it to.

[flyingace]

Exhaust is a contraption the P.O put onto it so that it would pass safety. It had no exhaust when he got it so he had to fab somethign up. It does have a few holes in it though.

Is there a guide for the spark plugs for the mixture? Im quite new at all this.

The bike does seem to roll easily in neutral. This is my first bike so I dont really have anything to compare it to.

As long as it rolls fairly easily, that should be OK. Just make sure the brakes aren't binding or wheel bearings locking up.

There is a plug guide on this site somewhere. Basically, you want a light tan to brown color on the electrodes. Whitish plugs are too lean. Heavy black soot means running too rich. Wet means no spark. Check them after running a while and shut engine down quickly.

Beg or borrow a compression tester. It may not be good news, but at least you know what the problem is.

[BassCliff]

Valves! It's what's for dinner!

Adjusting the valves is on my list of things to do later this summer... riding season up here is short so I want to get as much riding in as I can, and do maintenance at the end of the year hopefully.

HI Mr. djscottymiami,

I hate to be a stick in the mud, but ignoring your valve clearances is also a great way to shorten your riding season. If you have all the parts and tools it will take you an afternoon or less. Just do it. There's plenty of information on my website. Your bike will thank you.

Thank you for your indulgence,

BassCliff

[djscottymiami]

HI Mr. djscottymiami,

I hate to be a stick in the mud, but ignoring your valve clearances is also a great way to shorten your riding season. If you have all the parts and tools it will take you an afternoon or less. Just do it. There's plenty of information on my website. Your bike will thank you.

Thank you for your indulgence,

BassCliff

Where does one reccomend getting the shim changing tool (sorry, im not sticking zip ties in my spark plug sockets), feeler gauges and valve cover gasket? I read your tutorial and it says you changed the breather gasket. Is this a necessity?

Edit: I just went looking and found it at realgaskets. Is it any particular gasket material? I can grab a square of it from work if need be and just cut it.

As far as I can see this is all I would need to at least check the shims (ill check em then order any if i need some I guess).

As well, whereever I get this stuff from, needs to be Canadian Friendly, as I live in the northern parts of a province and cant be shipped ups. Is Z1enterprises any good? Wahts their speed for shipping.


Side note, I do have the 13L tank on my bike.. jeez that's tiny.

EDIT: Assuming that I do have the 13L tank:

6.5L -> 1.7USGal

*40MPG = 68miles = 109km

I guess my bike isn't doing too too bad? This is just ballparking it.

[djscottymiami]

Allllllllllllllllllllllllllllllllllllllrighty then. I did a little more reading on my initial welcome from Mr BassCliff. I now have on order the following from z1 enterprises:

Valve Cover Gasket
Metric Feeler Gauges
Cam End Plugs (just in case)
Valve Shim Change Tool (im already paying for shipping... so why not)

All for a grand total of 45$ \\/ a LOT cheaper then what i'd be paying locally.

All I'll have to do is go to work and cut out a breather gasket which shouldn't be too bad.

[twistedwankel]

I've got a 1980 GS850. The last tank of fuel I had in her, even tho there was a lot of idling and testing (because of my charging problems) she did 10mpg give or take :shock:
Any tips for a bike newbie?

Park the bike and drive a Hummer for better mileage:-D

[BassCliff]

Nice work. On my 850 (and a lot of other bikes) I must remove the breather before I can remove the valve cover. I figured as long as I have to remove it every time I check the valves I might as well get a reusable gasket (Real Gasket) for it too. This saves the cost of a new gasket every check and saves a LOT of time cleaning off the old gasket material.

Check the clearance on a valve, remove the shim and note the size, put the shim back. Continue until all the valves are documented. Then work out which ones you can shuffle around to bring most of your valves in spec (Mr. Steve's valve spreadsheet is very handy for this). Sometimes you can get by with ordering only one or two, depending on how many are out of spec. Do not turn the motor with any shims removed. You can damage your cams. Keep us informed.

Thank you for your indulgence,

BassCliff