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Diagnostic questions on FI bikes for Eddie

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A little history, (KX 450F 2011)I have had coolant temp. sensors issues in the past. I found that problem using the wiggle method. I replace the sensor and the connector on the harness, all was good for about 50 hours of ride time.

Yesterday the bike shut off in the air and fired back up upon touch down. When it started back up it was acting like it was missing. I started wiggling every connector I could touch to see if I could pin point the problem but there was no change. I disconnected the coolant temp sensor while it was running and still no change.

I didn't have an ohm meter at the track with me so I decided to change the plug just to see if maybe I fouled one. I have never fouled a plug in one of the four stroke bikes so I don't know how they react.

After about 10 minuets I had the spar plug in and it ran normal. Just to check I put the old plug back in and it also ran normal. Now I am freaked out because I know I didn't find the problem.

I am guessing the amount of time it cooled off corrected the problem but now how do I find it? Should I buy one of the inexpensive trouble code reader kits and see if it points me in the rite direction? I know it should show a coolant temp. code because I disconnected it.

I rode the bike for about another hour and kept the wheels on the ground and it never acted up once so now I am really freaked out.

Have you had any luck finding these type of gremlins?

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Hey Eddie maybe you can help me I also have a 2011 kx 450f and the bike won't start when it's cold but when it's hot it would start the mechanic told me it's the cdi which I find it had to believe can you be of any assistance

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Since the bike is efi I though maybe some sensor or electrical component

 

If the valve lash is in spec. my guess is you are thinking correct.  The problem is how do you find it?  Well, determination, knowledge, and some luck. 

 

The easiest way is to have a known good donor bike to borrow parts from until you find what makes the faulty bike run or the good bike not run.

 

If that is not possible then you need the manual, some testing tools, and most likely lots of time. 

 

The minor sensors will usually not keep it from running, such as the cts, iats, gear position sensor, and tps.  That's not to say that there couldn't be a intermittent short or open that may cause a hard fault that will keep it from running.

 

The major things that will keep it from running, stator, flywheel, ecu, maps, fuel pump, and so on.  Don't over look the wiring harness for shorts (rubbed through to ground).

 

Basically you need to rule out the simple stuff and move along one at a time until the problem is discovered.  Starting with most likely first.  That is where the experience comes into play.

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