Smoke Odd???

[CJM]

Rode last weekend for about 5 hours thru some very nasty rocks and some mud. I didnt bash any important lines, bolts, etc. It wasnt leaking anything. I was lugging around in 1st ALOT since the trails were sooo horrible. Also the idle kicked up a bit but I think its cause my exhaust had a leak.

Started it up monday and some white smoke came out, I pressure washed it a on sunday. I rode around a bit, it seems its not pouring out but whitish smoke comes out when I decelerate or hit the throttle.

Today I had to redo the lexx exhaust since the muffler clamp slipped while riding. Redid the clamp and changed the oil, oil had 8 hours on it. I decided to pour the oil back into the quart containers to see if its burning it. Nope, very close to 2 qts of oil came out. Oil was obviously used tho and black.

Changed the oil and took it out, its still smoking. Im using 15w-50 mobil 1, its not energy conserving or anything either. Had no issues with it the other day or before..dont get it.

So IDK. hoping to go riding in a few weeks and will keep ya'll posted but this baffles me. Also was just tuned by a reputable dealer too and runs perfect.

Oil is def not bluish or black, exhaust doesnt smell rich either. Airbox is coated inside with some nasty, sticky like oil tho.

[CJM]

Ok I checked it a bit more and searched

Valve seals maybe?

Smokes on startup after sitting, smokes on hard acceleration or when revving if its just sitting.

[honda400ex2003]

white smoke a 400 is usually moisture inside or the exhaust. it can be linked to liquid cooling antifreeze burning but we dont have to worry about that. if it was burning oil you would def be able to tell it would be darker blue or black. I would be willing to bet that some water got in the exhaust and down in the pipe a bit and was evaporating. if the seals were going you could smell the smoke and see the blue puff out the back lol. if anything start it up and go stand a couple of feet behind it right away and if you can smell it and see what it is then you will know for sure. that would just be my first inclination. steve

[CJM]

Yea but it cant have water in the exhaust this long. I washed it last week and I had to redo the exhaust totally today (it gets sealed with silicone). There was no moisture in it at all and riding it around for a good 10 mins shoulda killed the moisture anyways imho.

Both times I rode it today it would smoke upon start up, more you rev it up more smoke comes out. Then riding it, it would smoke when you accelerated. At one point when I accelerated a good cloud came out (this was right after it first started) If it sat idling or I just coasted no gas then it doesnt seem to smoke.

It didnt seem blue but more white, but its kinda hard to tell sometimes. I also checked the oil after riding it a bit and it took slightly more than 2qts in the end and I pulled out slightly less than 2qts.

So Im not exactly sure whats going on.

[honda400ex2003]

it is hard to say but it does sound like seals are going if you are sure there is no water in it at all. i was not sure how long you had ridden it for or anything so it was just a first guess type of deal. seals are easy to do if needed but if it really doesnt bother you, it could go for a while before it starts burning a ton of oil. just keep an eye on it and you will be fine for your ride at least. lol. i would take it back to the shop that did it and have them do the seals on it anyway or you can take the head off yourself and take it in. that is much easier than messing with the springs and stuff unless you have a compressor to do it easy. it is a bear without it, TRUST ME lol. i tried to do it without at one point. needless to say, it was done with my p and p, bore and valve lap. steve

[CJM]

Shop just tuned the carb for me and adjusted valves, before the ride the other day it seemed fine. I wonder if lugging it around in 1st did some damage.

Like I said, smokes on startup and when you give it gas. If it was truly pushing past everything it would smoke like nuts wouldnt it?

[honda400ex2003]

not neccessarly, mine were going on me for around 6 months and it still did not puff out much at all. you could smell it every now and again but that was about it. lol. they would seal decent until it was hard accel or it had been sitting over night or something like that. steve

[CJM]

In either case im helping a friend redo his topend in the next few weeks so it aint like I have a riding partner now anyways.

We can do his then mine :)

thanks for the help, did you find it hard to redo the topend?

[CJM]

Ok did some more work, I changed out the gas to make sure it wasnt something in it.

Nope, still smokes. Smokes whitish (possibly bluish tint its hard to see) when you rev it. When riding it will smoke when you hit the next gear-in the higher RPM you dont get much, also if you let off the hit the gas again its smoking.

So yea, probably rings right? Smoke imho is kinda white but its not pure white color.

[honda400ex2003]

I didnt think it was hard to do the top end on the 400. I had a service manual to do mine in case i had any questions. i could just check it out if needed. I would do a compression test first to verify that it is indeed the rings and not the seals. it seems like the symptoms you are describing are just the seals as it is only on accelerations and not all the time. steve

[CJM]

Main thing is tho, it just wont go away it seems.

I rode it a bit more today and I let it fully warm up and the smoke just pours out under acceleration. It also now pops when I shift down or let off alot. It didnt do that at all after i had the carb adjusted about 3 weeks ago. Infact it ran great then. Idle is there but slightly loopy I would say.

Also made no sense the idle raised for no real reason at all when I was riding that day and then the smoke came when I started it monday.

I think I should just do everything only b/c I would feel safer. Might as well check all the clearances and find out if Im SOL or good to go.

Im gonna run a compression test to be sure, but I think its just gonna be a rebuild and do it right.

[honda400ex2003]

do it all. get a 416 and put in there that is 10:1 and you will be set. you could get a stage 1 cam and have some major low end and mid to play with. do the seals, cam chain, and you will be set. steve

[CJM]

I already believe I have a hotcam in there, 416 might be pushing it I might do a 406 tho.

Mostly I would prefer to keep it as near stock as possible for reliability but I might change my mind.

Thanks for the help. Im currently tearing my friends down and doing the same thing (we think the head gasket failed) so should have more than enough expierance after that :D

[honda400ex2003]

read over the tear down section a couple of times and you will be set. I would say that you would like a 416 much better but it is up to you. I would suspect that a 416 would not be any less reliable than a 406 if built the same and maintained the same. if you torque it all and use quality parts there will be no problems with it. also on your buddies machine, tell him to check the head studs as they could have pulled out causing the head gasket problem. When you redo it, either use a stock or a cometic 3 piece steel gasket. steve

[CJM]

416 requires me to bore it of course? Dont even have a clue where I could send the head to do that besides a local machine shop. Ive heard there are places you can send the head too?

As for my buddies-the head musta been worked on before (bought it used) and they did a piss poor job, everything was lose!

[honda400ex2003]

you can send your head to just about any atv motor builder and they will do it for you. i had mine done at a performance shop with my bore to a 416. the cylinder would be bored to an 87mm instead of an 86mm for the 406 for the 416. not much of a difference i guess lol. either one will be fine and may run as good as the other. it is really hard to say since no one has actually had all of them lined up with the same things at the same time with the best jetting same tires, ect ect. too many variables to actually say which is actually best for a particular situation. if you went with the 406 then you could have 2 bores left. it is preference and dont let me influence your decision it is up to you. lol. that is too bad on your buddies machine, it sucks to have a machine that is used and potentially not taken care of properly. even if they are there is always the possibility of something happening. lol. I am going through this right now with my sled. i am replacing all of the higher wear stuff from the skis to belt and bogies and such possibly. lol. I am going to go through and check it all over even though the kid i got it from knew his stuff and took his time with the machine since he was a mechanic by trade. lol. steve

[hocman123]

yea i am his friend that the last owner didn't know what he was doing a bolt in the head was flat out missing, a differant bolt was replaced another with a allen head bolt that was 2 long. and i could have taken all but one or two bolts off the head with just my hands. then there was the tensioner and the valve caps that he lossened with a cold chiesle i think b/c there was deep marks and all of them and one i allmost didn't get off b/c it started to crumble

o and that *** was running it with about a extra quart of oil in it.

[CJM]

Do you have any good companies for the 416 kit? I saw JC performance for like 150 or so, any good? Im still debating honestly, but there is always time down the road.

[honda400ex2003]

The two best ones in my opinion are JE first then wiseco second. It is a close second though for me as I have had great luck with mine.

Also it sucks to find out about a machine like that. you should get a nice bolt kit so that you have everything new that you need to do it right. they are not very much and would really be alot better to have the correct bolts. steve

[matts27]

Originally posted by CJM
Main thing is tho, it just wont go away it seems.

I rode it a bit more today and I let it fully warm up and the smoke just pours out under acceleration. It also now pops when I shift down or let off alot. It didnt do that at all after i had the carb adjusted about 3 weeks ago. Infact it ran great then. Idle is there but slightly loopy I would say.

Also made no sense the idle raised for no real reason at all when I was riding that day and then the smoke came when I started it monday.

I think I should just do everything only b/c I would feel safer. Might as well check all the clearances and find out if Im SOL or good to go.

Im gonna run a compression test to be sure, but I think its just gonna be a rebuild and do it right.

Before I would tear it down I would check around the carb for a leak, sounds like it might be sucking some air around the carb boot to the motor. Mine burns a little oil, been for 2 years like that, been waiting for it to get worse before I tear into it just because I know it's the seals and she still runs strong. Just my 2 cents, good luck, Matt

[CJM]

Originally posted by matts27
Before I would tear it down I would check around the carb for a leak, sounds like it might be sucking some air around the carb boot to the motor. Mine burns a little oil, been for 2 years like that, been waiting for it to get worse before I tear into it just because I know it's the seals and she still runs strong. Just my 2 cents, good luck, Matt

Well considering the amount of smoke, I doubt its a carb leak for that. Maybe the popping, Ill check anyways.