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400ex black & white smoke

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I've only posted on here like once but my 400ex is blowing black and white smoke. I rejet the carb from 148 to a 155 main And thought if I dialed it down to a 152 it might help the black smoke but it did not.

 

I know I have an oil leak around the head gasket and the gasket under the valves. Would this be causing it? 

 

Still super new to mechanics  so any help would be appreciated thanks! 

 

I do have those gaskets ordered and on the way to be replaced

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The valve cover gasket could be allowing oil to seep through the header flange into the exhaust. That would explain your white smoke. But black smoke is the engine burning too much fuel! Nothing else causes black smoke. But if its cold where you are alittle black smoke in the winter is normal as the mixture and jetting wont be 100% correct. Unless of course you jet specifically for cold weather riding.

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Maybe it's just the cold then. I wish my camera would pick it up cause I would upload a video of it but it doesn't pick it up. I really need to change out the gaskets for sure. They are cheap pos gaskets from eBay. That was my first mistake 😂 thanks for the response!

 

Once the new gaskets are on I'll try to remember to update

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Be sure when you change the head gasket you torque it properly! Use 3 steps going up to 38 ft lbs. In a criss cross pattern! Hopefully you went with a multi layer steel gasket. Like cometic or oem honda. The valve cover needs to be metal on these engines! It can and will ruin the cam and head eventually if you use anything else. As that gasket serves two purposes. A spacer and gasket. Without the proper space its too tight on the cam journals for proper oiling. Dont sweat the black smoke in the winter. Wait for the temp to go up and see if it continues. Then worry about it if it does. Obveously within reason with this. If its a cloud of black smoke thats a different story entirely. But alittle puff here and there isnt anything to worry about for now.

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Last but not least spray this on both of the gaskets. Do it on both sides. It will stop the seeping oil entirely. I use it on all my gaskets and non ever leaked again. The credit for this next part goes to @TRX2FiveO. When you reach to 38 ft lbs of torque. Walk away for about 15 minutes or so. Come back and hit it again at 38. The metals will have flexed and you normally get another 1/8th turn or so on some of them.

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Why did u go up to a 155 then 152 from 148? Did u add an exhaust or  remove the air box lid ect? 

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The quad had an exhaust on it when I bought it, and had no motor work done to it. Original everything except the exhaust and few other things but no motor or carb work. So I figured I'd see if the 155 would help it any and it seemed to. But as slammed ranger is saying it might just be because it's winter. It's not much black smoke at all just a small puff when I rev it up.

 

And thanks @SlammedRanger I'll definitely be buying some of that spray then. The cheap gaskets that I put on it were the metal ones so I figured it would be okay but they were really cheap and it's the first time I've ever taken a motor apart, so I'm sure I didn't torq it down right. But I will be when I get these new ones. 

 

I get scared and have to carry a quart of oil with me all the time cause it seems to just go through so much. I hope it's just the gaskets 

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11 minutes ago, A&M OFFROAD said:

The quad had an exhaust on it when I bought it, and had no motor work done to it. Original everything except the exhaust and few other things but no motor or carb work. So I figured I'd see if the 155 would help it any and it seemed to. But as slammed ranger is saying it might just be because it's winter. It's not much black smoke at all just a small puff when I rev it up.

 

And thanks @SlammedRanger I'll definitely be buying some of that spray then. The cheap gaskets that I put on it were the metal ones so I figured it would be okay but they were really cheap and it's the first time I've ever taken a motor apart, so I'm sure I didn't torq it down right. But I will be when I get these new ones. 

 

I get scared and have to carry a quart of oil with me all the time cause it seems to just go through so much. I hope it's just the gaskets 

No problem bud! Always glad to help!

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@SlammedRanger do you know of having the spark Arrestor on will prohibit air flow? Ive never taken mine off and just did and it's about twice as loud as it was and could be a placebo effect but it feels more peppy. Could just be cause it's louder 

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Spark arrestor screen? So just the mesh screen in the end of the pipe? If thats what you are talking about yes. It will flow better and will be louder. I noticed when mine blew out. Throttle response was alittle more crisp and there was a small power increase.

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Well mine was an actual cover. Like an aluminum cover. It's super weird. You couldn't actually see the exhaust hole the exhaust came out the sides of the muffler. It's an fmf megamax. I'm gonna upload some photos and show you

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Its a copy of the supertrapp design. They honestly flow really well. And they are designed to be tuneable by adding or removing shims. Without anything on the end it will be obnoxiously loud! And you will run the risk of burning a valve having zero back pressure. The only difference you should have felt would have been if you were jetted wrong and removing it made you jetted closer to right.

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Well it seemed to run a little better but like I said could be just a placebo of the loud noise. It's twice as loud as it was before. So you think I should put it back on? I'm not doing any riding anytime soon so it's not like I'm gonna be goin on actual rides with it like that.  I honestly would probably prefer to have the stock exhaust. I'm not into loud noises hurts my ears 🤣

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I would run with the cover on! Do you have baffles to increase or decrease the power and?

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Okay I will, what about removing or adding some plates? Or should I just not mess with it. I can't really add any because what's on it is what came with it. 

 

I'd like to try out a new exhaust I found called a resonant racing, it's made in america. Sold by zoom zoom parts. Not sure if anyone here has had any luck with them. Plus it's only $300 for full exhaust

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1 minute ago, A&M OFFROAD said:

Okay I will, what about removing or adding some plates? Or should I just not mess with it. I can't really add any because what's on it is what came with it. 

 

I'd like to try out a new exhaust I found called a resonant racing, it's made in america. Sold by zoom zoom parts. Not sure if anyone here has had any luck with them. Plus it's only $300 for full exhaust

Never heard of them. I run hmf as they are local to me and sponsor my quad. I will have to look at it. Not often someone brings up something i have never heard of for a 400ex lol.

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Yea I think they are relatively new brand because I've never seen them before. It seems like a decent exhaust, but who knows I might have to be the one who experiment with it. 

 

That's awesome you've gotten sponsored by them, do you race? I'm still trying to do the youtube thing

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1 minute ago, A&M OFFROAD said:

Yea I think they are relatively new brand because I've never seen them before. It seems like a decent exhaust, but who knows I might have to be the one who experiment with it. 

 

That's awesome you've gotten sponsored by them, do you race? I'm still trying to do the youtube thing

Not as much as i would like too! I raced alot more when i was younger. But i have on my youtube channel the last few fair races i have done. The track is garbage but its a race right in my town at the county fair.

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7 minutes ago, SlammedRanger said:

Check my youtube channel out! I have go pro footage. 

 

 

Awesome I'm watching it right now

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