How To Keep A Honda 400EX From Overheating

Some mods that I made to keep my 400EX from overheating and ruining the top end... again.
Parts:
Main Jets (Rocky Mountain ATV) - $2.24 each
www.rockymount...
Pilot Jets (Rocky Mountain ATV) - $3.21 each
www.rockymount...
Exhaust Wrap (Amazon) - $19.99
www.amazon.com...
Add on oil cooler (Amazon) - $38.61
www.amazon.com...
Expanded metal for guard (Lowes) - $10.98
www.lowes.com/...
Honda Oil Pump (Rocky Mountain ATV) - $77.96
www.rockymount...
CFM Oil Tank (Ebay) - $229.95
www.ebay.com/i...
Dipstick Thermometor (XR's Only) - $42.95
www.xrsonly.co...

[@alexslifestyle1175]

I like how you just explained my problem in 2 minutes you got a new SUBSCRIBER ‼️

[@johnniecarter681]

Thanks for the info.

[@Davido50]

The CFM tank an rebuilding the existing oil pump system was best move . You won't have any issues. Be sure run a great motorcycle oil tho as I said.

[@Mudford]

I’ve been running the Valvoline Synthetic Motorcycle oil. I change the oil frequently because of harsh conditions of XC racing. Haven’t had any engine problems for three seasons.

[@gilbertcontreras54]

Can you post a video showing how to adjust the carburetor

[@midnightgunner9465]

Thanks for the video.

[@michaelpresey2273]

So you went up on the main to make it richer but moved the needle down to make the main jet leaner ? That makes total sense 👏 lmao

[@wyattelder7776]

Jesus loves you

[@slickricktheruler]

The needle controls the mid throttle. Main controls 3/4 to wide open throttle. Don’t feel silly buddy. You’ll learn. Don’t be cocky be humble.

[@stoneycarter5546]

that Cooler in the picture you show said cooler and guard I would have contacted them and asked wheres my guard, Maybe you can help me I have a 400 ex and I put a 440 big bore kit on it runs good and when I put 1.9 quarts oil in it don't read on my dip stick. the only way it reads is if I put in 3 1/2 quarts but it starts to spit it out the breather tube, do you know why it don't read correct with the right amount of oil in the tank, thanks for any help.

[@NoahMazraani]

I ride my 400 really hard on mx tracks in 100 degree Texas weather and haven't had any cooling issues yet.

[@Mudford]

DallasRider MX is a lot different than GNCC/Hare Scramble Racing. We run through mud, rocks, technical sections (1st, 2nd gear) and some short fast sections. In our series, we race for 1 1/2 hours. It’s pretty tough on machines. If your not familiar check out the RacerTV channel and watch some GNCC ATV races.

[@NoahMazraani]

@@Mudford I'm definitely familiar with gncc. That is definitely harder on quads then mx. I didn't pick up from the video that you raced xc since you never said it.

[@Mudford]

Sorry, I should have mentioned it in the video. I have a lot of videos out over the past 4 years. My memory isn’t the greatest. My two kids and I race ATV XC in Michigan.

[@antonsteroids2529]

I live in FL the same temp, a normal day 100 degrees. My 400 ex doesn’t have any overheating issues either.

[@antonsteroids2529]

Hol up. Maybe it’s because the faster you go the more wind cooling. Right?

[@chrismoulds7988]

Wrapping the header pipes all the way to the head is terrible advice to give. It helps keep heat in the head where you dont want it. 3 to 4 inches off the head is where it should be at you're essentially pushing heat back into the motor by doing that.

[@shredderdredder]

Great video sir

[@Mudford]

Thanks!

[@bernhard8540]

Was this really an issue with the 400s because I have two 2004 400ex's and when I got them about 7 years ago I tore them down and the one got a +7mm stroker and a stage 2 hot cam and a 440 big bore kit (cylinder replacement and all) and I ride for hours and have never had any type of heat issues they other one just has 440 big bore kit and a stage 3 hot cam but not stroker and they both run great with the stock oil coolers and everything the only "mod" they have is the shrouds under the front fenders to point air towards the motor.. that's all.. man if this is a big issue I'm glad I got two that don't have the issue

[@Mudford]

bernhard85 What type of riding do you do? I race Hare Scrambles. They are 1 1/2 hour races. I must not be the only one who has had overheating issues, because I see other 400ex riders with extra coolers, bigger tanks and/ or air shrouds at the races.

[@bernhard8540]

@@Mudford mostly enduro style racing is what I do but I also don't have a stock cylinder my cylinder is larger than the stock one to accommodate the 440 but I'm definitely not saying your not overheating I was just saying I'm glad I don't have that issue :) but is there anyway it could be poor oil circulation. .? Just askin :) I used to have a fan on the oil cooler but I removed it a few years ago because it was more of a pain than anything but I haven't seen any issues yet atleast.. I also have the metal wind deflectors under my front fenders to help the air flow over the motor (sorry I am having a brain fart and remember the proper name for them haha) I'm gonna start writing down my temperatures and compare them to a more stock quad and see how much of a difference there is for my 400.. :) hope you can get it sorted out though they really are good quads :)

[@tommybrumfield9062]

@@Mudford im haveing the same problem. just rebuilt my 400ex and and put new clutch and haven't got to ride it yet because just from starting it and letting it idel it sounds perfect but after about 10min of it just running its gets waay to hot to even want to try and ride,,, stil trying to figure this out and cant really find any videos on youtube about the cooler most are just talking about the oil tank

[@Mudford]

I would get the dipstick thermometer so you can see how hot it’s getting. You can try a bigger tank, but they are a lot more expensive. You can add a transmission cooler from amazon as an extra cooler cheaper. Maybe one with a fan?

[@tommybrumfield9062]

@@Mudfordthank for the info..and what would I look up just a regular transmission cooler for a car?

[@connersnow298]

Nice vid

[@Oneway_450]

Hey I installed a aftermarket carb and it’s runs great idles good but quarter throttle it turn off and if u hit full throttle automatically Starts running and not sure why it does that other then the quarter throttle problem it’s Runs great pls let me know

[@Mudford]

I’ve not had good luck with aftermarket carburetors. They are usually cheaply made. A friend of mine got one and his engine would idle rough and die when he touched the throttle. He opened up the carb and the jet was missing so it was just dumping fuel. When I opened up one, the jets were not marked with sizes making tuning more difficult.

[@Adamizon]

Hot hot should they run?

[@wyattelder7776]

Jesus loves you

[@noemiperez565]

Whats the price on the 400 ex

[@BigCityCountryBoi]

What is the maximum temperature for 400ex

[@Mudford]

From what I’ve heard, you don’t ever want to go over 300. Depending on where and how you ride your temps will vary a lot. I don’t look at mine when I’m racing, but it seems to run in the ballpark of 250 if I remember correctly.

[@BigCityCountryBoi]

@@Mudford thx

[@josuealvarez2845]

Did you have to remove the exhaust headers to install the oil tank cooler?

[@Mudford]

I don’t think so. Its been a couple years since I put it in. It’s a tight fit. I think I had to take it loose to take the exhaust out.

[@bbsonmyrims]

i got a 400ex bored to 440 wit a je 12:1 piston running on 110 with a stage 3 hotcam it has a oil cooler but still overheats you think a fan would fix it and where can i get one/how do i install it?

[@Mudford]

chrisshea000 I would check someplace like summit racing. A transmission cooler fan would be perfect.

[@myguitaryourface5160]

EBay has them but it doesn't matter my 440 has 1 and a oversized cooler,aluminum oil tank and air scoops and it has toasted my piston again,I'm going back to stock bore now

[@bbsonmyrims]

myguitar & yourface go with a 426 kit their good also

[@myguitaryourface5160]

@@bbsonmyrims I was told all bbk for a 400ex overheat,I didn't have these issues when it was stock bore 11.1

[@SmoothBlack187]

Piping noise on spark plug when acceleration .. what does that mean

[@Mudford]

Not sure what a piping noise is. Pinging? Is it running hot?

[@SmoothBlack187]

I mean sparking noise then when I trying to open full throttle it’s cuts off

[@davidblum_]

I have a 2000 a year older

[@chrisbarrier6839]

Whattttt😆🤣😂 you can't over heat it lol my glows red and shoots 3ft flames out exhaust it's maxed out on HP 120