KX450 Problem

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6/19/2018 7:05 AM

So just as soon as i got this thing fixed, i rode it in the mud and washed it, and now its hard to start. Ruled out valve clearance as its the same as last weekend when it started and ran fine. Also i can hook the bike up to a battery and it starts just fine. If i run it off the capacitor it takes 50+ kicks to start. The bike kept the battery voltage at 13.5 or so so im assuming the stator is fine. While testing the capacitor resistence, i noticed my meter would show OL as the resistence climbed up. The resistence does go above the 5k ohms the manual specs, but the OL reading that flashes concerns me. Im not sure if thats normal or if its indeed shorting out.

As of now the bike does get fuel, spark(even with the capacitor hooked up), and air. I noticed the voltage on the capacitor wont go above 3 when kicking. It just drops back to zero. Stator ohms out within spec. capacitor doesnt seem to hold a charge. If i connect the capacitor in series with the battery, the bike will not run. Any insight or experience with this?

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6/20/2018 5:29 PM

if you unplug the fuel line from the tank, does fuel leak out?

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6/21/2018 1:36 AM

Yes

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6/21/2018 2:05 AM

Fuel pump is the problem.

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6/21/2018 4:22 AM

Its a brand new pump with 2 hours on it...to clarify, fuel comes out of the line, not the pump itself. bike runs with a battery and doesnt run without one. Thats the problem, not that its not getting gas.

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6/21/2018 5:06 AM

How old is the battery?
Have you load tested the battery?

Paw Paw

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6/21/2018 5:08 AM

Battery is brand new & seems okay since the bike runs off it

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6/21/2018 7:55 AM

Could still be faulty, load test to the battery would be a good place to start

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RPM Performance
CT
783

6/21/2018 8:04 AM
Edited Date/Time: 6/21/2018 8:06 AM

The bike is supposed to run off the capacitor on the bike, not the battery. The problem with the bike is it will NOT run with the capacitor but WILL run with the battery. What i am trying to figure out is, is my capacitor bad or is the stator bad. Theres an apparent power shortage somewhere.

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6/21/2018 1:06 PM

I think you will find that the battery actually completes the circuit and you keep stating running it without the battery is the issue.

Paw Paw

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6/21/2018 1:25 PM

Are you saying i have a short in the capacitor then?

I was thinking the battery provided all the juice, not that it was completing the circuit

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6/21/2018 2:00 PM

Im getting spark, so i know theres power going to the system, my main concern i guess is why the capacitor wont charge more than 3-5 volts per kick. And also why it wont hold that charge for more than a few seconds. I hope this isnt causing confusion

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6/21/2018 2:27 PM

I am going to suggest doing some reading on the capacitor and it's roll in this circuit. To me, and I might be incorrect, it seems that in this install of the capacitor it is serving a purpose of being a "run capacitor" and not a "start capacitor". The fact that it does not hold the charge but for a very short time make me feel this way. Remember that the capacitor Plus and minus sides of a capacitor is only separated by a small this sheet of paper. If damaged it would discharge quickly. The other function of a capacitor is to keep the DC and AC sides separated. In most cases the alternator ( stator) generates an AC charge that has to be converted to DC and thus have to be kept separated. In that case it would be a "run capacitor".

Paw Paw

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6/21/2018 3:58 PM

Im not sure honestly. Its on every fuel injected kawi right in front of the cylinder head and mounted with the ignition coil. Im sure youve seen it. Its got the green plug by the stator plug. You have to disconnect it to hook up the battery.

I guess what ill do is just go ahead and try replacing it.

Other than that, if you get the bike going it runs as long as you want it to and runs great. Maybe it is a starting capacitor?

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6/22/2018 3:29 AM

So after studying the schematic of the bike, the capacitor is indeed a run capacitor. AC goes from the stator, to the rectifier, then DC power goes to the capacitor for the rest of the system to use.

I tested the capacitor before i left for work this morning. If i set my multimeter to ohms, the capacitor SHOULD start at zero and climb towards infinity. Of course thats not the case. It starts at 2.06 mega ohms and then immediately my meter goes to OL. For reference, my service manual says it should be over 5k ohms after 2 minuets. That tells me somethings wrong. I have a new one on order.

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