disconect "in gear" sensor

I disconected the sensor wire. Now it is easy to adjust the idle for more consistent starts. :)

Are there any negatives to this? Did you notice more engine braking on the bike, or not that noticeable?



p.s. I noticed that the kxf's on dealer floors have an extra protective bracket covering that wire right by the countershaft sprocket. Mine doesn't have it and it does look pretty exposed.

Does it allow for starting in gear now??


I disconected the sensor wire. Now it is easy to adjust the idle for more consistent starts. :)

No one cares about idle once u twisting the grip. How does it start in gear? Or does it start at all in gear?

You should care about how your bike idles, its one of the most important adjustments to make your four stroke start easy! :)

I feel that the sensor just threw in another unnessesary variable to deal with. Kawasaki or Suzuki had the idea that by increasing the idle would give the sensation of less engine braking, but some of us like engine braking.

I did not notice an increase in engine braking after disconecting the wire.

My bike starts great in gear when the engine, trans and clutch are at race temp, but when cold, it has to much drag on these parts to kick freely in gear. If you want good starting make sure your idle, fuel screw and pilot jet are corect. My settings are, good pace idle 3 turns out on the fuel screw and a 45 pilot. I ride from sea level to 6000feet. Use the hot start lever when the bike is warm or hot.

One more comment,

The worst thing you can do when trying to start a four stroke is to open the throtle! In my opinion, a sensor that basically opens the throtle more while in gear will only make your bike harder to start. :)

Turning up the idle is not "opening the throttle". Opening the throttle with a pumper carb will most definately make starting harder. Turning up the idle is a well know way to get your 4 stroke to start easier. Another way is just cracking the throttle, but that's a lot harder to do consistantly without slipping. I always run our idle high for easier starting.

The sensor has nothing to do with the throttle. It merely adjusts the ignition curve..

the big reason to avoid twisting the throttle on starting is the pumper carb dumps fuel in when you twist the throttle, so it is likely you'll flood the bike.

A friend of mine rode my bike several times last year (MX), he stalled it a few times, and every time he got it started again while in gear with only 1 or 2 kicks. He liked my KXF so much he went and bought an RMZ for himself.. He's a little frustrated as it won't start for him in gear..

I've adjusted his carb to be the same as mine and we'll see if that makes any difference. Others have mentioned that the proper carb adjustment does make a big difference in being able to start while in gear.

Raising the idle most certainly opens the slide, just like opening the throtle. If you are having to crack the throtle on your kxf when starting{squirting a small amount of fuel}, your pilot and or fuel screw is to lean. I am at 45 on the pilot and thinking of going to 48, 40 is stock.

I agree that the sensor only changes the ignition timing to achieve the idle change but incorect timing makes a bike harder to start also. I believe you need to tune your carb with only one ignition timing setting to get consistent starting.

Increasing the timing will increase the idle speed. Increased timing also makes a engine run hotter, this sensor may be the reason for all of our bikes running on the warm side. I will try testing this theory, its a long shot but very possible.

not a bad theory but I also think the radiators are a little small. let us know your results with your testing

..If you are having to crack the throtle on your kxf when starting{squirting a small amount of fuel}, your pilot and or fuel screw is to lean. ...

As I mentioned, only on the first start in the morning after the bike has sat all night do I do this, open and close the throttle just once or twice, and then commence kicking, (not like you crack the throttle on a 2-stroke).

The rest of the day, I just kick, no throttle, no hot start.

If I stall during a moto, I use the hot-start when restarting.

I'm not changing my jetting a bit. It pulls hard comming out of corners, runs clean on top, and almost no popping on deceleration. I'm able to start in 1 or 2 kicks when it cold, when it warm, when it's hot, and when it's in gear.. (although not when it's cold and in gear).

The only change I did to jetting is backing the fuel screw out 1/4 turn from stock.

Also, having the idle turned up a bit does not cause the carb squirt jet to pump any more or less. The squirt occurs as the slide moves from the down position to the up position.

Have u tried measuring the ignition timing change with the sensor on and off,in@out of gear? :)

I got my engine hot and then turned it off. I disconnected the gear sensor and nothing happened. All i know is that i connected it and now i can start my bike in gear. When the bike is warm it starts in gear. When i disconnected it i could tell when i put it in gear the rpms dropped more than usual but the bike was shifting like crap. It was harder to push the shift lever into the next gear. So im keeping mine connected.

Sorry about the long post but this is not something can be easily explained in a couple of sentences.

Disconnecting the neutral switch will not necessarily improve starting in neutral or in gear, and in theory disconnecting the switch should make the bike more difficult to start when cold.

Small displacement high performance 4 stroke engines are typically tuned to run at fairly high RPMs in order to make decent power. That means that at low RPMs the engine is inherently inefficient and can be difficult to start due to the extremely slow engine speeds while kickstarting.

Most modern high performance four stroke ignitions contain multiple advance curves to guard the engine from detonation, improve power, improve starting, possibly reduce noise, improve emissions, etc., etc. The ignition map is made up of several or many advance curves and depending on input data from sensors determining crank position, RPM, throttle position, and gear position (in or out of gear in this case), the control box selects an advance and sends a signal to the coil to fire at that given advance prior to TDC. Many four strokes also have a neutral advance curve that prevents the engine from revving too high when not under a load and to assist starting at slow engine speeds. Engineers who determine the ignition advances also know that when the bike is cold mechanical losses are greater, and that the bikes are going to be stalled, crashed, and whatever during races and must be easy to restart quickly without having to put the bike in neutral.

That said, getting back to the KX250F, when the bike is in neutral and the neutral switch circuit is closed, the control box recognizes that the bike is in neutral and selects a particular advance. When the bike is placed into gear and the circuit is opened, the control box recognizes that the engine is going to be brought up to more efficient engine speeds and adjusts timing continuously to optimize performance. That is what the neutral switch is all about, just another sensor providing data to the control box to optimize ignition timing at all times, even while starting in neutral or starting at engine running temp in gear.

Once you disconnect the neutral switch, as far as the ignition knows you are effectively always starting the bike in gear. It could be that what people are experiencing has more to due with poor technique and panicking while trying to restart the bike during a race than it has with the ignition. Since the circuit is opened once the bike is put into gear or the neutral switch is disconnected, the neutral switch will also have no affect on engine braking.

very well put. Finally someone who acually knows what there talking about :)

Yea what he said, hum

I had a problem making the bike start and run right with the old ignition box. I chased the jetting all over the place when my bike was new and the real problem was the inconsistent cdi. Removing the wire back then definately helped with the inconsistent nature of the bikes starting habits.

Since the new cdi I havent had the same issues as before and am currently running with the wire hooked up, although I have tried the bike without it and it doesnt seem to make much if any difference with idle speed, starting, or run quality like it did with the old cdi.

I sure am glad Kawi stood behind the bike and fixed that cdi because I was coming up with all sorts of hair brained ideas about what was going on with the thing :)

Why did you start this post? :)

You tell every body you disconnect a wire when you don't understand what the sensor does and then you back track that you changed the black box and hooked the wire back up.

This is just the kind of thing that gives a great bike a bad reputation! :D

At the time, unhooking the wire was helping with the bad cdi. After Kawasaki fixed the cdi I hooked it back up. Is that simple enough for you to understand. :)

Not a long post, but if you set your idle while the bike is in neutral, (and who doesn't?) Then there is no reason to remove the wire.

And, if you don't use neutral when you race around the track (and who intentionally does?) Then there is no reason to remove the wire.

It's there for all the reasons mentioned in the long post, but what it boils down to is: while the bike is in neutral, it allows you to set the idle to a normal speed for adjusting the fuel screw (do it every time you ride) and it increases the idle speed around the track in order to prevent stalling and lessen the engine braking. If you are never bogging down to near-idle speeds around th track, you won't notice any difference.

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