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Hi folks,
I apologize in advance if this topic has been beaten to death, but I really did try to search the archives and did not find an answer that completely relates.

My 2002 ST4s will not idle at the correct 1100-1200 rpm without the use of the fast idle lever. Since it is not an enrichener, I assume that I am not doing any damage, but I am not sure. Unfortunately, it means riding all the time with the lever slightly cracked open.
I am running Staintune slipons and a K&N filter, and I am not sure if the previous owner did a remap or not. I assume if not, it may be running lean, but I don't have any issues except at idle. Any advice on resetting idle speed would be much appreciated.
 

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How fast is your bike idling? My 02-ST4s idled around 900-1,000 rpm (according to the tach, which I know is not highly accurate) with no problems.
 

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It is on the throttle body assembly, total pain to get to the first time. Read up on the various sites about resetting the TPS and they will explain where the setting is. You may also want to go through the TPS procedure as well, probably get it to idle a bit more nicely.
 

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Discussion Starter #4
How fast is your bike idling? My 02-ST4s idled around 900-1,000 rpm (according to the tach, which I know is not highly accurate) with no problems.
About 900 rpm, according to the tach, but the bike will sound "lumpy" (think almost Harley-like firing) and then cut off shortly thereafter.
 

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About 900 rpm, according to the tach, but the bike will sound "lumpy" (think almost Harley-like firing) and then cut off shortly thereafter.
Definitely a problem you want to correct. Does your bike have one of those after market devices installed which enables you to start the bike with the kickstand down? My 02-ST4s had one which created starting problems. The problems disappeared after the device was removed.
 

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Discussion Starter #6
Definitely a problem you want to correct. Does your bike have one of those after market devices installed which enables you to start the bike with the kickstand down? My 02-ST4s had one which created starting problems. The problems disappeared after the device was removed.
I recently removed the sidestand bypass, and the overall performance improved, and startups are quicker and more determined (fewer cranks of the starter before the engine fires up) but I still have to use the fast idle lever to do so, in all temperature ranges, both the air temp and the engine temp.
 

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Its an awkward screw to get at without raising the tank but you can spot the idle adjust screw on the horizontal throttle body linkage.Reach in there with a small spanner and turn the screw til you get it idling where you want.
The others are prob correct in saying you should check the TPS and balance at the same time.......but to simply lift the idle speed all you need do is turn that screw.

Colin 02 ST4S
 

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Its an awkward screw to get at without raising the tank but you can spot the idle adjust screw on the horizontal throttle body linkage.Reach in there with a small spanner and turn the screw til you get it idling where you want.
The others are prob correct in saying you should check the TPS and balance at the same time.......but to simply lift the idle speed all you need do is turn that screw.

Colin 02 ST4S
Thanks to you and the others that are replying. I will give that a try first, and get to the TPS later, since it looks like I will need to pick up a specialized tool for that. This is my first Duc, and also my first liquid cooled/lots o' electrics bike. I've always done my own maintainence, so this is definitely a learning process.
 

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The TPS thing sounds more complex than it actually is and can be done with a simple multimeter very effectively.
My ST was also my 1st Duc and seemed a bit overwhelming initially. I found these forums and LT Snyders manual a great way of realising that things are not really so difficult for a DIY guy.....and more than that, its hugely satisfying to find that the slightest tweak can make a huge difference on the way the bike performs.
Dive on in there!

I've had my bike back on the road a week now after winter layoff and maintenance and it's sooo good to be back riding that noise and feel.


Colin.
 

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If it was fine before, but has started to worsen over time, then you may want to be sure of some simple things are in order before you take a screw driver to any adjustments.

Look inside your throttle bodies at the interface between the butterflies and the bore. If you see a ridge of built up gunk, grab a can of carb cleaner and wet a rag with it. Clean all that gunk off. Worked for me when mine started to get "sluggish" at idle. That ridge on gunk on by bike was restricting air flow at idle. It was rich, and idled too low.

Make sure your air filter is clean and also check your plugs.
 

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Had a similar issue with bike & having to use fast idle. Turns out I overfilled the gas tank & got gas in the charcoal canister venting system. Ran brake cleaner through the canister to evaporate residual gas and also found a loose hose clamp so tightened all clamps on gas tank & canister hoses, solved my issue.

Also agree with SS' posting about cleaning up ridges and checking air filters, plugs, etc. I have also occasionally used a few ounces of acetone added to gas to clean up fuel system- it cleans the fuel system much better than any gasoline additive, but I would only use it occasionally before a ride; some people have said they believe excessive use of the acetone sitting long periods in the system can break down plastic & rubber. I've used the acetone sparingly for years and never had an issue, but wouldn't take any chances, I just do a few (4-5) ounces a couple of times a year before a long ride. Seems to work.
 
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