Replacing thermo unit need help

[MX450]

I accidently broke the little tab on the thermo unit off and need to replace it. It looks like there is some sort of sealant on the threads of the thermo unit what is this?

[Ruf Racing]

Originally posted by MX450
I accidently broke the little tab on the thermo unit off and need to replace it. It looks like there is some sort of sealant on the threads of the thermo unit what is this?

You can solder another connector on the sensor. You can use any
type of pipe thread sealant.

[eastside 400]

or you can just wire your fan to ground instead of the tab so it will run all the time. but if you are putting the sensor in, i use anerobic sealer/gasket maker but like said before any pipe sealer will work

[MX450]

yea i was thinkin about running the fan all the time

how exactly do i do that?

[Scro]

Originally posted by MX450
yea i was thinkin about running the fan all the time

how exactly do i do that?

All you have to do is ground the wire that goes to the thermo sensor. If the fan doesn't come on when you ground it, something is wrong with your fan.

[MX450]

i read somewhere u also have to take out the thermostat is that true or do u just have to ground the wire?

[Scro]

No, you don't have to take out the thermostat. The thermostat will open and close like normal because it is controlled by the temperature of the coolant. It's not opened and closed electrically by that wire.

[MX450]

So all i have to do is ground this wire (cirlced in green)? Just cut it and ground it to the frame?

[Scro]

Yep

[lilguy450]

not to hi jack this thread but does anyone know the diameter of that hole? Like if I were to buy a brass plug for it and replace the sending unit and just seal it off?

thanks

[MX450]

ok a guy on another forum said that grounding that wire will make the bike think its overheating and cause it to retard ignition timing...

he said to ground the green wire that goes to the blue plug

[Scro]

Originally posted by MX450
ok a guy on another forum said that grounding that wire will make the bike think its overheating and cause it to retard ignition timing...

he said to ground the green wire that goes to the blue plug

I've done it to several of my bikes without issues. They all ran the same, except the fan was on. I'm not sure which green wire he is talking about.

[Sjorge450R]

Originally posted by MX450
ok a guy on another forum said that grounding that wire will make the bike think its overheating and cause it to retard ignition timing...

he said to ground the green wire that goes to the blue plug

that makes no sense. The sending unit simply turns on the fan. It doesnt adjust the timing at all. You can try it for yourself. Just hold the wire on a ground location when reving the engine. Nothing will change.

pretty sure our quads dont have an ECU where it can retard timing when it overheats and what not lol These are basic mechanics.

[eastside 400]

it theory it actually could, the fan circuit is part of the ECU, ive heard this said before but im not actuall sure, i always have mine grounded so im not sure

[DnB_racing]

Originally posted by FlewByU352
pretty sure our quads dont have an ECU where it can retard timing when it overheats and what not lol These are basic mechanics.

Flew is exactly right! these quads only have a CDI (capacitor discharge ignition) roughly meaning that on factory set limits the cap will go to ground and discharge, causing a lower spark output.
For spark advance or retard it would need some sort of a CPU (central prossing unit) the processor is the portion of a computer system that carries out the instructions of a computer program to make a variable spark timing.

[MX450]

yea im just gonna put the new thermo unit on it and be done with it lol