idle issue

[brewmister]

I'm having a problem with the idle on my 1982 GS750 E. I have dipped the carbs and installed new o rings and the gs runs well. The problem is the idle is set to specs and sometimes when stopping at a traffic light the r
rpms drop and i have to restart the gs . It doesn't happen all the time .
I just thought someone else may have had the same problem .

 

[Big T]

Have you adjusted the valves?

 

[brewmister]

idle issue

Valves were adjusted to specs.My GS idles great until i run it and stop the the rpm's drop to approximately 750 rpm and after a few seconds returns to idle spec .
Could i have mixed up the main jets or pilots jets after chemical dip or are they the same on CV carbs on this 1982 GS750E ?

 

[DannyMotor]

Sounds like a lean issue... try turning in your air screws 1/4 turn.

If it's not that... float height may be slightly too low (high if the carbs are flipped upside-down on the bench).

 

[BassCliff]

Hi,

The '82 GS750 has CV carbs. There is no "air screw" per se. It's an "idle mixture screw". And I have also heard that having the idle circuit too rich can cause that behavior, where the idle dips. Where are the idle mixture screws set?

Yes, float height could be too low. Is the petcock and vacuum line in good shape and operating properly? Is the air filter over-oiled? Is the fuel line pinched or routed funny? Did you use aftermarket "carb kits"?

Thank you for your indulgence,

BassCliff

 

[brewmister]

idle issue

1) No aftermarket carb kits used
2) New vacumn line with no leaks
3) New OEM air filter
4) New petcock from Z-1 checked and works correctly
5) Fuel line routed correctly and not pinched
6) Float height 22.4 mm
7) idle mixture screws set as follows #1 (1 3/4)#2(2 1/8)#3(2 1/4) #4(2 1/4)
I did find a small amount of oil originating from the airbox coming out the drain tube.

 

[Nessism]

Did you vacuum sync the carbs yet? And I'd set all the mixture screws to 2.5 turns open and see if that helps.

 

[brewmister]

idle issue

I did vacumn sync and later in the morning i will set all 4 idle mixture screws 2 1/2/



Thanks for the support

 

[brewmister]

idle issue

the idle mixture screws were set a 2 1/2 from gently seated .The gs ran fine for about 30 minutes of hard riding then noticed the idle issue had resurfaced . Pulled into garage and was going to check battery charge and saw the white wire with green tracer and the adjacent red wire had melted very badly .I know the carb settings had nothing to do with the melted wires . I had recently installed new water proof connections on these wires . Any insight would be appreciated .

 

[BassCliff]

Hi,

It sounds like you may not have the stator connected directly to the r/r unit. There is a loop of wire that runs up to the handlebars going to a non-existent headlight on/off switch. That loop of wire can be bypassed, cut back, taped off. Connect the three output wires from the stator directly to the three input wires on the r/r unit. Run the ground wire from the r/r unit directly to the negative terminal of the battery. Make sure all charging system connections and grounds are clean, make sure the fuse box is clean. If you like, you can run the r/r output directly to the positive terminal of the battery through an inline 15 amp fuse assembly.

Try the "quick test" and see what it tells you about the charging system.

GS Charging System Health+Quick Test


Thank you for your indulgence,

BassCliff

 

[Nessism]

Hi,

It sounds like you may not have the stator connected directly to the r/r unit. There is a loop of wire that runs up to the handlebars going to a non-existent headlight on/off switch. That loop of wire can be bypassed, cut back, taped off. Connect the three output wires from the stator directly to the three input wires on the r/r unit. Run the ground wire from the r/r unit directly to the negative terminal of the battery. Make sure all charging system connections and grounds are clean, make sure the fuse box is clean. If you like, you can run the r/r output directly to the positive terminal of the battery through an inline 15 amp fuse assembly.

Try the "quick test" and see what it tells you about the charging system.

GS Charging System Health+Quick Test


Thank you for your indulgence,

BassCliff

Cliff is da MAN!!! Read his advice and FOLLOW IT!!!

Too bad more people don't do preventive maintenance on their charging systems before problems occur.

 

[brewmister]

idle issue

1) I had the stator connected to the rr
2)Ground wire from the rr connected directly to negative terminal of battery
3) GS Charging System Health & Quick Test was conducted prior to this meltdown with good results
4) I will run an inline 15 amp fuse assembly to the positive post of battery
5) I will look for the loop of wire that runs to a non -existing headlight on
and off switch

Since i had the output wire of the rr wired to the red wire coming out of the harness do i just tape this up ?

 

[MisterCinders]

1) I had the stator connected to the rr
2)Ground wire from the rr connected directly to negative terminal of battery
3) GS Charging System Health & Quick Test was conducted prior to this meltdown with good results
4) I will run an inline 15 amp fuse assembly to the positive post of battery
5) I will look for the loop of wire that runs to a non -existing headlight on and off switch

Since i had the output wire of the rr wired to the red wire coming out of the harness do i just tape this up ?

Sorry for the slight hijack, but this bit intrigued me.

My charging system seems to work fine, though I will do the stator/RR/ground re-wire soon just in case.

My bike actually has a headlight on/off switch. How does that affect the rewire options? Will I need to bypass that switch and convert to an "always on" light?

 

[koolaid_kid]

Sorry for the slight hijack, but this bit intrigued me.

My charging system seems to work fine, though I will do the stator/RR/ground re-wire soon just in case.

My bike actually has a headlight on/off switch. How does that affect the rewire options? Will I need to bypass that switch and convert to an "always on" light?

No, do not change it. The "Always On" was a Federal mandated change. They thought (probably incorrectly) that it would make bikes more visible to cages. Hasn't worked for me, anyway, I am still invisible when I ride.

 

[MisterCinders]

Will cutting that wire from the stator to the headlight to reroute it to the RR affect my headlight operation? I suspect not, but . . .

 

[koolaid_kid]

Will cutting that wire from the stator to the headlight to reroute it to the RR affect my headlight operation? I suspect not, but . . .

Not a bit. We always strongly suggest removing that loop and connecting all 3 stator wires directly to your R/R.

 

[AJ]

Back to the original question, an idle sag then settling up is usually an indication of too rich a mixture, as noted by BassCliff. Too lean can make the idle hang high. Since your mixture settings (post #6) appear to be on the lean side of the stock screw settings, is there any chance your pilot jets are a size larger than stock?

 

[andtheacademics]

Back to the original question, an idle sag then settling up is usually an indication of too rich a mixture, as noted by BassCliff. Too lean can make the idle hang high. Since your mixture settings (post #6) appear to be on the lean side of the stock screw settings, is there any chance your pilot jets are a size larger than stock?

When you say "hang high" are you describing the opposite problem? Say come to a stop light, RPM might drop to 1500 for a few seconds and then return to 1000-1100? Or does "hang high" mean, just idles high? Trying to get my terminology down and I've heard a lot of people use "hanging idle"

 

[AJ]

When you say "hang high" are you describing the opposite problem? Say come to a stop light, RPM might drop to 1500 for a few seconds and then return to 1000-1100? Or does "hang high" mean, just idles high? Trying to get my terminology down and I've heard a lot of people use "hanging idle"

"Sagging idle" is when the bike drops below desired idle speed momentarily say down to 500-700 rpm, and then comes up to proper 1100 idle rpm. This is usually due to too rich a mixture and leaning the mixture screws will cure it (assuming the pilot jets or air jets are stock settings).

"Hanging idle" is when the idle refuses to come down momentarily before dropping to normal idle rpm, or sometimes the idle never comes down. Hanging could also be much higher than 1500, perhaps 3-4KRPM. This is usually due to too lean a mixture caused by 1) air leak, 2) too lean mixture screw setting, 3) partially clogged pilot jet.

Of these two conditions, hanging idle can be harder to diagnose, because people start fiddling with multiple other settings to get it to idle when the pilot/low-speed circuit is not working right. For example, they might adjust the idle upward with the idle speed screw which is actually opening the butterflies, or the bike is running on the "enrichener" or "starter" circuit and they "can't get it off choke".

 

[AJ]

From post # 6

7) idle mixture screws set as follows #1 (1 3/4)#2(2 1/8)#3(2 1/4) #4(2 1/4)

One more thought, your idle mixture screw settings appear to indicate that you should be on leaner than stock settings (typically 2.5 turns), but the "idle sag" says too rich to me.

If your pilot and air jets are indeed stock sizes, then it is possible that your float level is too high and you might try adjusting the floats downward.