1980 GS850 poor gas milage and other random questions

[Kato76]

I just finished a 1980 shaft driven GS850 project, the bike was given to me by a friend that has been deployed to Iraq, with the only asking price was to see it on the road. So I was adamant the whole summer to get it running. Now that it's running, I'm getting only about 23 mpg everyone I've talked to regarding this says I should be getting at least 40 mpg. So what gives on that one.

The second thing it seems that the it doesn't have really any torque in the upper gears (4 and 5) even when down shifting from 5 - 4 it seems that it's never enough to get up that hill.

How often should I change the hypoid gear oil in the rear wheel.

and how much is the proper amount for engine oil.. I know there is a little window there but I'm curious to see if there is an actual measured amount that I should be putting in there..

thanks in advance
J-

[SPARKSS]

Your fuel consumption is high. The obvious question concerns any fuel leaks.....it wouldn't take much of a leak to cause that sort of reduction. Is the air filter dirty (especially if an oil foam element) and or the inlet to the box restricted (this alone will cause a big loss of power and rich operation). Does it run smoothly with no black smoke out of the tailpipe? Black smoke indicates overfueling (or unburned fuel). This may be a symptom of a carb problem OR of incorrect ignition operation, timing or timing advance (this will impact your power as well). If the engine is running rough, start by verifying ignition first and check to see if any or all of the plugs are being fuel fouled (black sooty deposits on one or more) - this may help to isolate the problem. Has the valve lash been checked? Valves held open or leaking usually cause fuel and/or combustion problems by themselves.......and aggravate any other problems (ignition or carb) that may be happening also.

More questions than answers - for what they're worth.

[mark]

I'd do a compression test as well to determine the general condition of the engine. Check to make sure all cylinders are firing. Check that you have good spark at all your plugs and proper voltage to the coils, also that your coils are within spec. Make sure your spark plug caps have good connections to the plug wires.

[Kato76]

Ok.. thanks for the info first off.. I was fiddling around with it to further my understanding of the problem plus changing the oil. So I started pulling plugs to see if there was any rich pistons or any other problems... PROBLEM.... the number 2 and number 3 spark plugs aren't sparking is this bad coil packs or could something else be causing this .. the number 1 and 4 plugs are on the same coil packs respectively (1 with 2 and 3 with 4).,..???/

so I'm a confused if the coil pack went bad wouldn't it stop all spark and not just half??

thanks in advance

[49er]

Ok.. thanks for the info first off.. I was fiddling around with it to further my understanding of the problem plus changing the oil. So I started pulling plugs to see if there was any rich pistons or any other problems... PROBLEM.... the number 2 and number 3 spark plugs aren't sparking is this bad coil packs or could something else be causing this .. the number 1 and 4 plugs are on the same coil packs respectively (1 with 2 and 3 with 4).,..???/

so I'm a confused if the coil pack went bad wouldn't it stop all spark and not just half??

thanks in advance

The HT leads from the left coil (when sitting on the seat) should fire 1&4 plugs, the other coil fires 2&3. You probably have a dud right coil. Check that the low tension leads are attached/making clean contact on that coil. You are lucky that the engine pulled the bike at all with two pots out. There must have been plenty of engine vibration as well. This will be the main cause of your poor performance and fuel economy.
After market replacement coils (Dyna and others) should be fitted in pairs with the correct rating for the igniter pack/CDI unit.