surge at +/- mid rpm's

[leveredge]

Mid RPM +/- range the bike "surges". Any thoughts?
1981 GS450L. 18k miles.

[tkent02]

Take your carbs apart and clean them.

[Kaiser Sosei]

And don't forget new O rings from Robert Barr,

www.Cycleorings.com ? I think that's right.

[Nessism]

Assuming the bike is stock and all the various maintenance items, such as valve adjustment, are up to date, first thing I’d do is clean the carbs (like the others have already suggested) and replace the various O-rings, including the intake boot pipe O-rings, with parts from cycleorings.com. Sync the carbs after cleaning and make sure the air filter is clean and properly oiled. If the bike is still surging, I’d shim the needles; remove the plastic washer on top of the needle clip and replace with a couple of metal washers about ½ the thickness of the original spacer.

If the bike is modded with intake or exhaust changes, you will have to rejet the carbs. Good luck with that.

[Steve]

OK, I agree with all the previous posters, but we need a little more definition on "Mid RPM +/- range".

Are you talking barely holding the throttle open with it in neutral, or a little more throttle in, say, third gear, or are you talking about full throttle in top gear? It would be a different answer for each of these situations, because the different circuits that need to be adjusted depend more on throttle opening than they do on engine speed.

.

[twistedwankel]

Mid RPM +/- range the bike "surges". Any thoughts?
1981 GS450L. 18k miles.

Shortly after surging at 2/3 throttle in 5th gear my 82 GS450L with 12k miles (not ridden in quite awhile)developed a problem.

My wife swore she could smell gas at nite. Our bedroom was over the storeroom where I kept the bike. I being a man told her she was nuts.

Two days later when I got the bike out there was a puddle of gas dripping slowly out one vent tube.

One float was stuck slightly open. AND I owed my wife an apology for not believing her nose that can out sniff a blood hound.

Clean your carbs before the gas drips on your hot exhaust and catches fire!! Mine had some nasty slime in there. Be thankful there are only 2 carbs.

[49er]

If you run an inline filter, check that it's not partially clogged and flowing fuel at the correct rate. Also the petcock filter in your tank, could need cleaning.

But as others have suggested, you may need to clean the carbs too.

[leveredge]

OK, I agree with all the previous posters, but we need a little more definition on "Mid RPM +/- range".

Are you talking barely holding the throttle open with it in neutral, or a little more throttle in, say, third gear, or are you talking about full throttle in top gear? It would be a different answer for each of these situations, because the different circuits that need to be adjusted depend more on throttle opening than they do on engine speed.

.

Under motion cruising. About 1/2 throttle/ RPMs. I think mid gears. Especially cruising in 3rd /4th and 5th. Gets better after it gets warm. I think it's better when throttle more open. I'll have to check. I don't ride the bike much. It's my wifes. I was thinking carbs but really didn't want to mess with them. Best get at it I guess. Thing is it's running now! When I get done with it, it might not be!