MKIII slightly lean

JimNH said:

Thanks gentlemen,

The bike was parked for 20+ years. Carburetors were cleaned including the idle passage. The symptoms I experience is that on high speed running it makes a little better power at slightly less than full throttle which I take as a lean condition. Now I don't remember it having that many years ago but at that time I had a GS1150 that I used for spirited riding and may not have noticed it. I did install new fuel taps and it's possible that they are more restrictive. A good test would be to try it with both taps open. It's too cold now and I'm just wondering if the general experience is that larger main jets are necessary as I will replace them while I'm making some other changes like sleeving the master cylinder.

If there's no consensus I'll leave it alone and try both taps open and a throttle chop if that's no help.

Click to expand...

acotrel said:

JimNH said:

Thanks gentlemen,

The bike was parked for 20+ years. Carburetors were cleaned including the idle passage. The symptoms I experience is that on high speed running it makes a little better power at slightly less than full throttle which I take as a lean condition. Now I don't remember it having that many years ago but at that time I had a GS1150 that I used for spirited riding and may not have noticed it. I did install new fuel taps and it's possible that they are more restrictive. A good test would be to try it with both taps open. It's too cold now and I'm just wondering if the general experience is that larger main jets are necessary as I will replace them while I'm making some other changes like sleeving the master cylinder.

If there's no consensus I'll leave it alone and try both taps open and a throttle chop if that's no help.

Click to expand...

Have you checked the breather on the fuel tank ? If the main jet is too lean you can check it with a plug chop. If the midrange (needle and needle jet) is too lean the bike would cough as you move up and down through the gears opening and closing the throttle. Both of those are useless as indicators if there is a partial vacuum created in the fuel tank as it empties.

Click to expand...