Page 1 of 1

Engine lopes at idle. Carb sync?

Posted: Mon Mar 10, 2014 3:41 pm
by erikwillke
I searched but didn't find a definitive answer. My 96 SE lopes at idle (warm or cold) from 1k to 1.k rpm at a steady rhythm. lope. 1. 2. 3. lope. 1. 2. 3.

suggestions

(this bike is new to me and I have done no maintenance on it. plan on oil change, plug and air filter change, and timing belt change.)

Re: Engine lopes at idle. Carb sync?

Posted: Mon Mar 10, 2014 4:13 pm
by virgilmobile
My uneven idle was caused by a near plugged slow speed jet on one carb...
Other things will affect it also...ANY vacuum leak....under the thermal mat,at the carbs,at the intake tubes,etc,etc..
All old hardened or deteriorated rubber vacuum lines are suspect.

A partially "on" choke....Even if the lever is off,the enricher valve can stick open a little.

Sync the carbs is the first and easiest thing to do..Add a little Sea Foam to the fuel while your working on it..Hopefully it will magically fix itself.

If these steps don't,prepare for some quality time deep in the bowels. :D

Re: Engine lopes at idle. Carb sync?

Posted: Mon Mar 10, 2014 6:47 pm
by ct1500
Surging idle would be due to a lean condition, most likely plugged carbs followed by vacuum leaks.

Re: Engine lopes at idle. Carb sync?

Posted: Tue Mar 11, 2014 7:27 am
by erikwillke
thank you both.

update:
I ran seafoam in it for my 180 mile trip. no improvement. I think i'm going to look at vacuum before I tackle the carbs. Thoughts?

Re: Engine lopes at idle. Carb sync?

Posted: Tue Mar 11, 2014 7:46 am
by dingdong
Looks like you will be pulling the carbs. There is a vacuum line under the black rubber mat under the carbs on the left side that has a 90ยบ elbow that gets a hole worn in it. It is a very common problem. Here is a link that has some info regarding this problem.

viewtopic.php?f=6&t=18626

Re: Engine lopes at idle. Carb sync?

Posted: Tue Mar 11, 2014 8:57 am
by robb
Check the rubber tubes above the middle plug on each cylinder. They crack in a 90 degree radius and create havoc on the idle.

Re: Engine lopes at idle. Carb sync?

Posted: Tue Mar 11, 2014 9:11 am
by SteveB123
erikwillke wrote:thank you both.

update:
I ran seafoam in it for my 180 mile trip. no improvement. I think i'm going to look at vacuum before I tackle the carbs. Thoughts?
Did you do your filter and plug changes yet?
Start with the easy stuff.

Re: Engine lopes at idle. Carb sync?

Posted: Tue Mar 11, 2014 11:16 am
by erikwillke
SteveB123 wrote:
erikwillke wrote:thank you both.

update:
I ran seafoam in it for my 180 mile trip. no improvement. I think i'm going to look at vacuum before I tackle the carbs. Thoughts?
Did you do your filter and plug changes yet?
Start with the easy stuff.
Not yet but i will very soon.

Re: Engine lopes at idle. Carb sync?

Posted: Tue Mar 11, 2014 4:58 pm
by Fatwing Chris
Before you tear anything apart.Open the fuel door and there will be a knob in there beside the fuel cap.This is an idle adjustment knob and sometimes just winding it in and out a few times will cure an idle surge.No guarantees,but it's worked before(actually worked on my 89 a couple of years ago).There's been threads on this cure on the forums over the years.Don't forget to reset your idle speed when done if it works.

Re: Engine lopes at idle. Carb sync?

Posted: Tue Mar 11, 2014 5:42 pm
by bellboy40
+1 on what Fatwing Chris said about the idle adjuster. Mine was surging at idle from about 1k to 2k rpm. I adjusted the idle knob up and down a few times and left it at about 800 rpm and it has been running very smoothly since (about a year now). I don't have a clue how that could help the idle but it does seem to work a lot of times.

Re: Engine lopes at idle. Carb sync?

Posted: Wed Mar 12, 2014 7:14 am
by erikwillke
That's awesome. Thanks. I'll try that.

Re: Engine lopes at idle. Carb sync?

Posted: Wed Mar 12, 2014 11:11 pm
by Bluewaterhooker0
One other thought. You ran Seafoam and took a 180 mile trip, but your problem is one at idle. I had the same problem on my '97 a year ago and ran the Seafoam, but also let it idle quite a bit, as I believe there are idle jets in the carbs that won't be active at driving speeds. You might try it again with some of the other suggestions as well, and concentrate on a lot of idle time to get the Seafoam into those jets. Also, the longer the Seafoam sits in those jets, the better it is likely to do its job. So idle a lot, let it sit stopped, idle more, etc. Worked for me.