Overheating?

[iwannagofaster]

Hey guys I got an 03 400 bored to a 407 stage 2 cam 2mm oversized intake valves hmf full system main jet is a 170 can't remember pilot off hand.....the other day I was riding and it seemed like my header was real hot so I checked it with a laser thermometer and it read 350 my oil was at 250 according to my xr's only dipstick I'm running 20w50 oil just wanted to see if anyone has ever checked there header temp ......my plug is burning perfect cardboard brown thanks for any help

[slightlybent47]

Hey guys I got an 03 400 bored to a 407 stage 2 cam 2mm oversized intake valves hmf full system main jet is a 170 can't remember pilot off hand.....the other day I was riding and it seemed like my header was real hot so I checked it with a laser thermometer and it read 350 my oil was at 250 according to my xr's only dipstick I'm running 20w50 oil just wanted to see if anyone has ever checked there header temp ......my plug is burning perfect cardboard brown thanks for any help

Are you running the same fuel?
Sounds like the oil is a little heavy.
I run Rotella witch I think is 15w-40
Being that there air cooled, you must keep some speed up to keep air flowing over the motor.
Try a lighter oil, and change the octane on your gas and compare the temps and see if it runs cooler.

[iwannagofaster]

Im gunna try 10w40 and only run high test pump gas

[slightlybent47]

My ex tends to run hot if I don't keep good air flow going.
Riding slow trails will make it run hot.
You can add a spall fan and an over sized oil tank.
I run a bigger oil tank but no fan.
You also can put a bigger oil cooler for better cooling.

[slightlybent47]

Im gunna try 10w40 and only run high test pump gas

My ex tends to run hot if I don't keep good air flow going.
Riding slow trails will make it run hot.
You can add a spall fan and an over sized oil tank.
I run a bigger oil tank but no fan.
You also can put a bigger oil cooler for better cooling.
The head pipe really could use a heat shield near the head to keep heat off the head.

[JOHNDOE83]

If you guys are running hot it is not normal, you need bigger jets.

[JOHNDOE83]

I bet if you try atleast a 190 main jet you will see a difference in temps and performance.

Cardboard brown on your plug is irrelevant and has no meaning on your jetting other then your needle is set correctly.

you gotta do a plug run and actually cut the threads off your plug in order to "check your plug"

To properly jet a 4 stroke for main jet you need to go big on jets until it will not rev out all the way and stutters like a rev limiter, then you back down jet sizes until it fully revs out and your jetting for main jet will be perfect.

If you dont believe me its right here from the biggest jet supplier in the world www.jetsrus.com in the faq section under jetting procedure for main jet tunning.

with the bore, cam, valves you deff need bigg jets.