[claystang22]

this post is coming before ive had a chance to try out my new cfm aluminum air scoops, but i dont think they are the save all to my issue

as we all know, 400ex's are known for overheating. and suggestions on how to remedy this issue?

thanks for your input!

 

[XplicitRacing6]

Welcome to the Forums. What do you mean by "As we all know, 400ex's are known for overheating" Something must be messed up because it should never do this. UNLESS..... Do you have a bore on it??? That would be useful info.
Those air scoops should help out a little.

 

[SlammedRanger]

Yeah 400ex's only over heat when people dont know how to tune them properly. When tuned right they will not overheat. They do come from the factory with a lean tune. To meet emissions.

 

[claystang22]

Yeah 400ex's only over heat when people dont know how to tune them properly. When tuned right they will not overheat. They do come from the factory with a lean tune. To meet emissions.

in terms of internal engine work, the motor is stock (except for the exhaust). I took it into my local Honda and had them do a full tune up on it not long ago. they removed the air box and jetted it up. now, it overheated a little before they did this, and im almost certain that it is not running lean. its not overheating to the point that my headers are glowing or anything, but that i have to stop and let it cool off for a little while after pushing it for and hour or two because it starts burning my leg. I was under the influence (from other forums ive read in the past) that 400ex's have a tendency to run hot compared to other quads. it definetly runs hotter than my brothers 350 raptor or my uncles raptor 660

 

[SlammedRanger]

Do they run hotter? Yes. They are only air cooled. But overheating is a whole different story. I have ran my quad wide open for hours on end mostly on the rev limiter or near it. And have never been even close to overheating. I have air shrouds, and a fan on the stock oil cooler. Thats the extent of my cooling mods. Only time they actually overheat would be in the dunes at slow speeds. And again bumping your jetting to the rich side can 100% solve that. My .02

 

[XplicitRacing6]

I have rode my 400 in some extremely hot and humid conditions for long periods of time (Like slammed said). It sounds like you need to wear thicker pants or move your leg further away from the exhaust. Did you have shorts on when you rode? Do you have an exhaust shield on the right side of the quad? I know those help a lot with keeping your leg from burning up. Next time you ride use a heat gun and see how hot your quad actually is. You really don't want your quad to be above 200 degrees F you can run higher but that is what I try to keep all my quads temp at

 

[billy5221]

Your aftermarket exhaust might be causing it to run hotter than the stock one. Like others have said I too had one and never had a issue with over heating, it's was a 02, it was all stock. I remember riding it on some pretty hot days too.

 

[SlammedRanger]

Yep infered heat gun at the base of the cylinder head right where the head gasket is. Under 200 is what you aim for. 250 or more you have to start worrying a bit. If you see over 250 your in for a piston seizure before long.

 

[UnkleRaRa]

Do you have a just a slip on, or a full exhaust?

I've burned 3 pairs of paints because of my fmf header, but never close to over heating.

That's why I wrapped it, hoping to salvage the pants I have left haha.

It's just the nature of the air cooled motor coupled with the aftermarket exhaust, and the fact that it sits right beside your leg doesn't help at all.

 

[SlammedRanger]

Do you have a just a slip on, or a full exhaust?

I've burned 3 pairs of paints because of my fmf header, but never close to over heating.

That's why I wrapped it, hoping to salvage the pants I have left haha.

It's just the nature of the air cooled motor coupled with the aftermarket exhaust, and the fact that it sits right beside your leg doesn't help at all.

Get you a pair of riding pants. They have leather on the inner calf that and good riding boots and you dont even feel the heat at all. Everyone should ride with good boots even if your just messing around. Broken ankles suck real bad!

 

[claystang22]

i wear purpose made riding pants. I think i might try jetting it up for sure though. also might consider adding a fan with a temp. switch on it

 

[SlammedRanger]

Yeah if your feeling it through riding pants you are getting dangerously hot. But from your sig it looks like you ride dunes alot. Which is pretty much like riding inside an oven. I gurantee if you told that honda shop that they would have or atleast should have upped your jetting to the max of the rich side to keep it cool enough to not seize. The general rule of thumb im aware of and i have never actually ridden sand dunes at all. Is 2 or 3 steps bigger on the main jet and another half turn of fuel on the mixture screw. Keep in mind that the closest dunes to me is 9 hours. So someone that rides dunes may have a better more real world tested theory. Thats just what i read and what i plan to do if i ever go to the dunes.

 

[UnkleRaRa]

Get you a pair of riding pants. They have leather on the inner calf that and good riding boots and you dont even feel the heat at all. Everyone should ride with good boots even if your just messing around. Broken ankles suck real bad!

Yeah at the end of last summer I picked up a full ANSR suit.

The pants are incredible, and have the leather patch your talking about.

The pants that burned were just some light slush pants, but my buddy and my girl both burned their snow pants on my header last winter before I wrapped it, lol.

 

[XplicitRacing6]

i wear purpose made riding pants. I think i might try jetting it up for sure though. also might consider adding a fan with a temp. switch on it

Make sure you get a pulling fan

 

[claystang22]

Its basically just a slip on exhaust system (white bro's e-series). the headers are aftermarket, but pretty much identical to the stock ones except there is no place for a heat shield. Ill probably do something about the jetting to, I never really trust my local honda to service it anyways (its really just a car dealership with a couple of quads thrown in and a few mechanics who dont really seem to bright to me. Any suggestions on the size of jets i should be looking for?

 

[XplicitRacing6]

Its basically just a slip on exhaust system (white bro's e-series). the headers are aftermarket, but pretty much identical to the stock ones except there is no place for a heat shield. Ill probably do something about the jetting to, I never really trust my local honda to service it anyways (its really just a car dealership with a couple of quads thrown in and a few mechanics who dont really seem to bright to me. Any suggestions on the size of jets i should be looking for?

Not sure on the Jet sizes thats @SlammedRanger 's Specialty
I will say thought that the heat shield helps a TON. I didn't have a heat shield on my 416 ex and my leg got extremely hot. Once I put one on I don't have my leg burning alive anymore

 

[SlammedRanger]

Without your elevation and ambient air temp i dont know for sure. I would do a 42 pilot jet for sure. Im curious what they put in it for a main jet. I would think a 175-180 should be enough for dune riding bit again i dont have first hand experiance with that type of riding. Were pretty much jetting for that at this point not what it will run right with in other places. Do you mainly ride dunes? Im just going off your sig here.

 

[claystang22]

thats basically all i ride anymore.

 

[claystang22]

and elevation is basically at sea level

 

[claystang22]

Oregon Dunes Sand Dune Guide