Red hot

[2010rmk800144]

bought a 04 kfx 400, seemed to be fine, let it idle now for like 4 mines and the pipe coming off the cyclinder is red hot..... and ideas why?

 

[synergycycle]

bought a 04 kfx 400, seemed to be fine, let it idle now for like 4 mines and the pipe coming off the cyclinder is red hot..... and ideas why?

Thats normal as long as it does not overheat.

 

[Med1ogre]

You may be running lean. you might need to rejet.
Is the airbox lid on? are you running a pipe? hows the plug look?

 

[imdoo'n]

Thats normal as long as it does not overheat.

can't believe that at all.

 

[2010rmk800144]

i think theres a 150 in there right now for jetting, i hant really rode it i bought it off a guy i know pretty well and i pulled the plug off that he had and seemed good, however we did screw the piliot jet to where it was supposed to be, and the seats on but no airbox lid, i was told its supposed to be ran with it off and has been for the last 3 years, and they actually discontinued the airbox cover, and yes theres a pipe put on there by a kawi dealer when it was purchased by the first owner... that fan. is it supposed to run all the time or just when it gets to a certain temp, bcuz it wasnt on just as it was idling and we tested the fan by hooking it up and bypassing and the fan fired right up, so are they suposed to come on at a certain temp or what??? i was also having starting problems which were fixed by my dad doing something with the choke cable, but now i have idling problems like its idling way to high, and no matter how many times u turn the idle screw or whatever it is it doesnt settle down, but when you go back to the way the cable was before we touched it, it barely starts

 

[kbrunlees]

Check you carb for looseness. If is the slightest bit loose you will have starting problems.

 

[2010rmk800144]

what about the pipe and fan any idea?

 

[FossY]

ure most likely just to lean
know lots of bikes that had the glowing header

after some carb and jet work all gone

 

[2010rmk800144]

the fans not suposed to come on at a certain time or anything?

 

[Med1ogre]

Well i would think your main is close, since it really has nothing to do with idling anyhow.i would put your mixture screw back to 3.5 turns out and go from there or...
Bring engine to norm. operating temp.
Turn Idle up a little(200-300rpm)
Turn mixture screw in 'till engine stumbles
Back screw out 'till idle smooth out
Turn screw out 1/4 turn more
Return idle to normal. but i think 3.5 will be close with your setup

if its a aftermarket header its gonna glow some, the wall is much thinner. if its stock, somethings not right.
the fans on a sensor and comes on when the coolant reaches temp.

 

[Med1ogre]

and tell your dad to get his paws outta there, dam dads anyway:d

 

[ghglenn]

It is absolutely normal. Everyone freaks out the first time they see this.... The head pipe is thin. They all turn red hot at idle. Not lean. Don't freak out. However, as the temp (outside goes up), you will need to rejet, as this will cause a lean condition. Only way to do this is to ride it. Since the plug looks good, don't touch it until warmer outside. It may be fine, unless your buddy rode it during winter and jetted it down for it.

Here is a basic guide. If you need more help, just ask. Keihin Carburetor Tuning

 

[2010rmk800144]

well he said he only rode it for summer and thats the way it was set up

 

[synergycycle]

Exactly every 4 stroke that has decent performance does that. Every 4 stroke mx bike I have had has done that even when they are jetted rich, my dads XR250 trail bike even did this. My yamaha yz250f will do this if I let it idle for like 2 min! Do not let the thing idle for that long.

 

[synergycycle]

Here are some example vid lol

[media]http://www.youtube.com/watch?v=rBhrWzQNCQY[/media]
^and that is a 150cc!!

also make sure your idle is to spec.

 

[2010rmk800144]

Well i would think your main is close, since it really has nothing to do with idling anyhow.i would put your mixture screw back to 3.5 turns out and go from there or...
Bring engine to norm. operating temp.
Turn Idle up a little(200-300rpm)
Turn mixture screw in 'till engine stumbles
Back screw out 'till idle smooth out
Turn screw out 1/4 turn more
Return idle to normal. but i think 3.5 will be close with your setup

if its a aftermarket header its gonna glow some, the wall is much thinner. if its stock, somethings not right.
the fans on a sensor and comes on when the coolant reaches temp.

so thats the black screw on the righthand side, and screwing it in would mean closing it like turning it to the right?

 

[2010rmk800144]

Well i would think your main is close, since it really has nothing to do with idling anyhow.i would put your mixture screw back to 3.5 turns out and go from there or...
Bring engine to norm. operating temp.
Turn Idle up a little(200-300rpm)
Turn mixture screw in 'till engine stumbles
Back screw out 'till idle smooth out
Turn screw out 1/4 turn more
Return idle to normal. but i think 3.5 will be close with your setup

if its a aftermarket header its gonna glow some, the wall is much thinner. if its stock, somethings not right.
the fans on a sensor and comes on when the coolant reaches temp.

Here are some example vid lol

[media]http://www.youtube.com/watch?v=rBhrWzQNCQY[/media]
^and that is a 150cc!!

also make sure your idle is to spec.

how ot i check the idle to spec , and thats a crazy video haha thats what mine looked like

 

[2010rmk800144]

and so the fan just kicks in when it needs too? like when its sitting there idling and red hot isnt that hot enough for it to kick in?

 

[synergycycle]

and so the fan just kicks in when it needs too? like when its sitting there idling and red hot isnt that hot enough for it to kick in?

the fan goes off on coolent temp not the pipe temp.

 

[2010rmk800144]

alright so the glowing red is okay... im not sure if its an aftermarket header or not i kno the pipe is.. do u have any idea as to what the mixing screw is suposed to be at