Power Loss At Speed Gs 1100

[stevepoole1]

Hi Folks
I have been meaning to post this question since the season ended here (Maine), been so busy this is my first chance. Snow is on the ground and I am getting ready to dig into winter maintainance after the holidays. Here is my question:

I have a 1982 GS 1100 that I just bought last summer. I have not done much to it except new stator and regulator/rectifier. The bike really runs great, except at prolonged highway speed. I use it for everything, including a commute to work which puts me on the interstate for a while. It runs great as long as I do not exceed 70-75 MPH. Whenever I go over 75 MPH for any length of time, my acceleration just "bogs" down. The motor sounds OK, not coughing or anything, its just that all of a sudden the speed goes to crap and the bike drops down 10-15 mph. I can "force" it by twisting the throttle, but that's not right. What the heck? Anyone have any idea what might be going on?

[paco13]

sounds like a fuel problem to me.
Is the bike stock?
Petcock working ok?
Hows the air cleaner look?
Ever clean carbs?

[walt]

i agree it sounds like a fuel problem to me as well. because it happens at higher speed i would check for two things first. look at the fuel line very closely for a tight turn. not enough to stop the fuel flow but enough to slow the fuel flow. then if a fuel filter has been installed remove it and try next year without doing any changes. be sure to drain the float bowls for the winter. the reason for waiting till spring is, anything you change now you can't test.

[NelanCustoms]

my 850 does that off the start, i sealed the airbox tight, boots are good. maybe i can try what he is gonna try with the fuel system

[walt]

the kinking or tight bends are from a fuel line that is too long. the two causes are the stock line is cut and a fuel filter added that makes the line 1~2 inches longer. the other possibility is the PO replaced the fuel line and it's too long.

[NelanCustoms]

how long should my fuel line be? there is a fuel filter on it i see now

[TheCafeKid]

It should be as short as possible and as straight up and down as possible. Especially with a fuel filter in it. If the fuel filter is cocked sideways even just a bit it can slow the fuel flow down enough, especially at high speeds where the fuel is obviously being used at a quicker rate. Remember the fuel from the tank to the carbs is more or less gravity fed.

[gustovh]

One thing not mentioned that was a problem on my 1100 is vacume locking in the fuel tank. The cap does not vent properly causeing a partial vacume and fuel starvation. The next time it happens, pull over and crack the cap and continue on. if the problem dissapears for a while, you know what it is.
V

[chef1366]

As said above. Bad petcock or bad venting from fuel tank.
If that doesn't do it how is the air filter?
Clean the carbs from here

[stevepoole1]

Thanks for good advice

Thanks for all the responses, and the good advice. I will get busy with this asap and hopefully resolve the problem. Thanks again!