79 850 getting poor fuel mileage

[Guest]

My friend's 79 GS850N only gets low 20s for fuel mileage. I checked on the forum, and it appears that he should be getting mid to high 30s.
What should I look at? He bought it last year and has only put around 500 miles on it since then. I rode it when he picked it up, and it seemed to run O.K. But he is a no-maintenance kind of guy, so he has not changed points, plugs, checked timing, nothing.
At first, I thought it was the carbs, but now I am not so certain.
Since I will be the one doing the work, I would kind of like to know which area to attack first.

[GSstiny]

Tire pressure, an air filter and plugs would prolly help alot. If the wires are old and crappy they may need replacing too. A word to the wise, test the coils first, you dont want to put new wires on a coil thats about to crap out. Points and condensers should have the gap checked, replaced if they are questionable. Once its firing like it should be (fat blue spark=good) take it for a ride and see if the clutch is slipping, if so, adjust accordingly. If the carbs are the root of the trouble it can get a little more tricky, but keep it simple and youll have it running like new in no time.

[mark]

Tire pressure, an air filter and plugs would prolly help alot. If the wires are old and crappy they may need replacing too. A word to the wise, test the coils first, you dont want to put new wires on a coil thats about to crap out. Points and condensers should have the gap checked, replaced if they are questionable. Once its firing like it should be (fat blue spark=good) take it for a ride and see if the clutch is slipping, if so, adjust accordingly. If the carbs are the root of the trouble it can get a little more tricky, but keep it simple and youll have it running like new in no time.

Right. You need to go through the bike and do the routine maintenance and checks. Valve adjustment, timing, point gap, condensers, cleaning electrical connections, plugs, carb cleaning etc., air filter, making sure your airbox is sealed good, battery in good condition. On an bike as old as yours without a lot of maintenance it probably needs some good TLC.

Get a good manual and go though the routine maintenance procedures.

[koolaid_kid]

Get a good manual and go though the routine maintenance procedures.

Is a Clymer's good enough to do all this? I don't have the bike or the manual, so I don't currently know. Personally, I have never been impressed with Clymers. I always buy the factory service manual for mine, but this guy did not take my advice to buy one.

[GSstiny]

Is a Clymer's good enough to do all this? I don't have the bike or the manual, so I don't currently know. Personally, I have never been impressed with Clymers. I always buy the factory service manual for mine, but this guy did not take my advice to buy one.

A clymer will suffice for general maintenance. Ive been pretty pleased with the clymer's Ive had, but if I was going to be diving into crankcases, transmissions, etc, Id prolly spring for a factory one.

[koolaid_kid]

Good point, GSstiny. I prefer the level of detail of the factory manuals, but the Clymers is aimed at the weekend mechanic who just wants to keep it running well.
Seems to me that a basic tuneup (points, plugs, condensers, air filter) is an excellent first step. There was something about the bike (its been over a year) which suggested to me that the PO had not maintained it in the manner that a true GSer would have done.
Should be interesting.

[GSstiny]

Should be interesting.

Thats the one part of GS ownership/maintenance that never fails...ever. Good luck reviving it