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Discussion Starter · #1 ·
i just bought a 1987 250 fourtrax and the electrical was a mess..that has been fixed but the problem i face now is that while riding it the oil temp light come on when you rev the engine while shifting and cruising and it goes off when you slow down the rpms is this normal or do i have a major problem:noworktomorrow:

please help this is to good of a atv to let something simple blow it up
 

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No, that's not normal. If it's not hot, then your oil temp sending unit might be bad.
 

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Discussion Starter · #3 ·
the man i bought it from said he changed the oil i wonder he he got the filter in wrong or did not chaneg it at all and it is starving for oil at high rpms?
 

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the man i bought it from said he changed the oil i wonder he he got the filter in wrong or did not chaneg it at all and it is starving for oil at high rpms?
If you think the oil filter might be in backwards, you better check it and see, because it will destroy the engine if it is in backwards.
 

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Here is how to check the oil temp sensor and the alarm unit that activates the oil temp light. This is for a Honda Fourtrax 300, but the checks should be similar to the Fourtrax 250.


 

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How many manual do you have Geez!!! LMAO I would love to have a library of honda repair manuals I would sit up all night and read...lol
 

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Discussion Starter · #7 ·
thanks helmut i will try that in the morning ...i checked the filter and it was installed correctly and had plenty of oil in it ...would not having a battery on the 4 wheeler have any adverse affects in the operation of the sensors ? like i said i just bought this atv a week ago and this is the first time i was able to get the connectors all plugged back in and the electrical working on it ..
 

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thanks helmut i will try that in the morning ...i checked the filter and it was installed correctly and had plenty of oil in it ...would not having a battery on the 4 wheeler have any adverse affects in the operation of the sensors ? like i said i just bought this atv a week ago and this is the first time i was able to get the connectors all plugged back in and the electrical working on it ..
I don't think not having a battery would cause it to do that, but if you run it a long time without the battery, it could eventually cause the stator to go bad. But I'm talking about days or months probably.
 

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How many manual do you have Geez!!! LMAO I would love to have a library of honda repair manuals I would sit up all night and read...lol
I have 35 manuals, but they're not all Honda manuals. I have some Honda, Yamaha, Kawasaki, Suzuki, and Polaris.
 

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Discussion Starter · #10 ·
well i said morning but i went back outside anyway and cheked the ohms on the sensor and it showed what he book said ..... but yet when you shift into gear and rev the engine the light starts glowing dim and the faster you go the brighter it gets ...i am stumped...does this sensor show low oil pressure and temp or just temp
 

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It's just oil temperature. Are you sure the wiring is right, because that sounds like how the charging system works, without a battery. Without a battery, when you turn the headlights on, they will be a little dim and then as the engine speed increases they will brighten. I'll bet the wiring is still messed up. You could try a battery, just in case, but I doubt that's the problem, because I've run them without a battery before and mine didn't do that. I would say the wiring still isn't right.
 

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i wished that there was a way to check the pressure
I can't remember, but do those 250's have the oil line that runs up from where the oil filter goes to the top of the head or valve cover, like the 300 has? If it does, you could loosen the top bolt a little and crank the engine over and see if oil squirts out from around the bolt. You still wouldn't know the oil pressure, but at least you would know if the oil pump was pumping.

Yamaha engines have a bolt at the top of the head that you can take out and screw a line in to hook up an oil pressure gauge, but I don't think Honda has one.
 

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Does the oil temp light come on when the engine is cold, when you first start it up? If it does, the engine can't be hot that quick. All the oil temp sensor is, is a thermal sensor. It just changes resistance with the change of temperature, so if the engine isn't hot, then it has to be an electrical problem. The oil temp sensor don't measure oil pressure. It just measures oil temperature.

By the way, make sure you have a good engine ground. A bad ground could possibly cause that. The charging system may be trying to ground through that wire, somehow.
 

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Discussion Starter · #15 ·
i will check that ..and you made a great point if you loose ground on a trailer it will try to ground through anpother bulb in the circuit ...thanks helmut i will try that tomorrow also willl loosen the oil line and chek to see if i am getting plenty of oil volume...
 

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Discussion Starter · #16 ·
yes it does come on for about 10 or 15 seconds then it goes out and stays out and then only when you rev it does it light up...now you have me thinking that when the voltage builds in the stator and no battery to put the charging system under a load then it might try to balance out through what ever path it can take......it is late and i hope i made some sence
 

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yes it does come on for about 10 or 15 seconds then it goes out and stays out and then only when you rev it does it light up...now you have me thinking that when the voltage builds in the stator and no battery to put the charging system under a load then it might try to balance out through what ever path it can take......it is late and i hope i made some sence
Yeah, that could be the problem.
 

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Discussion Starter · #18 ·
:rating10: well goodnight for now and thanks for the help i am about whhooped and going to bed and thanks again will do some mmore checking and let you know what i find when the sun comes up
 

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OK, you're welcome.
 

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Discussion Starter · #20 ·
just to let you know helmut i hooked up a battery to the honda 250 and was able to use the electric starter and the oil/temp light come on key first on then off and when i rev the engine it did not come back on ...i even checked the voltage going to the sensor and it had 12 volts .....so it must have been that lack of battery....
 
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