Off-idle hesitation

[Anonymous]

Hi Guys,

I have a '81 gsx1100e with 65000km on the clock that has hesitates just off idle (1-2000rpm). Beyond 2000rpm is not a problem runs beautifully.

I suspect that the idle mixture is not quite right, just a little lean? I don't have a problem with the charging system, just done the valve clearances and synchronised the carbs in the last week. Newish sparkplugs (2-3 months old). However, the ht leads are the originals and could do with replacing, but whats the best way to replace them without damaging my coils?

Any suggestions or ideas?

Thanks,

Anthony
New Zealand

 

[Anonymous]

My totally stock, low miles '81 does the same thing. I've written it off as being the result of lean carbs (that'll work just fine until I have to have them off). If your hesitation only bothers you when leaving a stop, as with my bike, it's usually just a matter of consciously opening the throttle a bit more as you begin to release the clutch. If you're riding it around at less than 2000 rpm you're asking too much of the engine. Okay for HDs, but these engines are made to rev. It's actually remarkable how well they pull from 2000 rpm - a characteristic of the TSCC setup. In anything but first gear in traffic I don't usually see the tach at less than 2500 rpm, and usually more like 2800/3300 idling around town.

 

[Anonymous]

Interesting that you've noticed it to. The problem only arises with slow take offs in traffic as you state and I normally give it at least 2000rpm anyway.

Thanks

 

[Anonymous]

Interesting that you've noticed it to. The problem only arises with slow take offs in traffic as you state and I normally give it at least 2000rpm anyway.

Thanks

try lookIng at your plug color--the situation that you have is identical to my bike when i run with the megaphone open--if Your idle is ok then in all probabilitY your idle adjustment is ok--I believe this happens when you are taking off easily which means the needle is not up high enough to give a rich enough mixture when you are going from the idle jet to the mid range needle jet.I CAN CAUSE THIS TO HAPPEN WHEN I AM CRUSING SLOWLY AND THE ENGINE IS LOAFING--THIS MEANS THAT THE SLiDE IS ALMOST CLOSED.. TRY TO SEE IF IT OCCURS WHEN YOU ARE ON A LEVEL ROAD OR A SLIGHT DECLINE WITH ALMOST NO THROTTLE--WHEN YOU SLOWLY ROLL ON THE THROTTLE IT WOULD BURP A BIT BUT UPON APPLYING MORE THROTTLE IT CLEARS UP---
the solution is putting a small washer under the needle jet mounting point to raise it up a hait--but usually this symptom is a sign of a carb that iwill give the best gas mileage during normal cruising. again look at thr color of your plugs.

I do this on purpose when i pass the harley shop to give the illusion that I am running wild cams :lol:

 

[Don Lobacz]

Your hesitation is the result of a leanness in the pilot system. The carbs were set up lean from the factory, but they have undoubtably become worse with time. Regardless, there is no reason to live with it. The air/fuel screws are on the top & front of the carbs and may be hidden under the factory plug (to keep owners from messing with it). These plugs can be removed by CAREFULLY drilling them out (just barely break through), screwing in a sheet metal screw and pulling/wiggling the screw/plug out. The adjustment screws may be siezed in their threads, so if they don't move easily, put some penetrating fluid in and come back later (heat may also be necessary). Before removing them, find out their setting by gently screwing them in and counting the turns it takes to lightly seat them. When you remove the screw, keep in mind that there are still 3 things down in the hole: a spring, a washer, and an o-ring (don't let the carbs flip upside down). The tip of the air/fuel screw will probably be black with soot, and this alone may be enough to cause the hesitation. The soot may come off just by spinning the tip in your pinched fingers, or you may need to lightly spin it in a fiber pad. Spray some gumout down into the hole and replace the a/f screw, gently seating it down and then backing it out the original # of turns PLUS an additional 1/4 turn. I usually do one carb at a time.

IF the plugs are already out of the carbs, you should be able to do this without removing the carbs from the bike (or if you have a low clearance drill and a lot of patience). If you pull the carbs, you may as well clean them too, paying particular attention to the pilot jet (make sure that you can get a fine piece of copper wire to go through each one).

 

[Anonymous]

Great stuff thanks Don, sounds like a job for the weekend. I'll also checkout my plugs as well.