2005 honda 400ex spitting black oil out the exchaust

[bigdady536]

I have recently acquired a 2005 Honda 400ex and it smokes like hell. It smokes out tons of white smoke when giving it gas. The guy i got it from said he put 2 stroke oil in the tank to help with seals a crap but i think he just said that to cover up why it smoked so much. I got a good deal on it so I'm just curious on what steps i should take to start fixing it. I have read a few different ideas but everybody's symptoms are different. Mine seams to be smoking like army smoke bombs and contains black oil at the end of the exhaust, and even spit out black oil through a little pin hole crack in the exhaust slip on. I was going to start replacing the fuel and then running it a bit but i don't think that will solve the problem. The next step was i was going to check the valves and adjust them to the right spacing. I am just curious if anyone can help me with figuring out what my next steps should be and what I'm getting my self into. I am fairly good mechanically just not a pro at diagnosing symptoms. Also if you reply to this message i would really appreciate it if you can explain in anyway possible how to check the possible solution. Like if i adjust the valves are there seals that need to be replaced, i'm not even sure if they have seals. If i have to do the top end what exactly is needed to do the job. Thanks for any help.

[BEAVER.989]

Hate to say it, but it sounds like it's time for a rebuild. Piston, rings, bore and hone, minimum. While you're in there replace the timing chain and valve seals and adjust the valves.

[nakomis0]

Well if it has 2 stroke oil its gonna burn crazy. Drain that crap and run some fresh gas in there.

If it still has problems then yes you are going to have to go in and do a whole topend. Which from what it sounds the minimum is going to be a new piston rings w/ a hone, and complete valve replacement/ reseating whatever the valves need. Piston stuff you can do yourself the valves gotta be done by a pro.

[bigdady536]

about how much am i looking to be spending in parts for a top end rings, piston, valve seals, do you think i really need new valves, and what about the cam chain and what ever someone had mentioned. I am pretty good at what ever i get my hands on just need a little guidance. Please if anyone can throw some pretty accurate calculations on cost per item the would be great. Please price out the items so maybe if one thing is still good i don't have to purchase. Also any news on where to get inexpensive but good parts other then local dealers and ebay. Any news regarding how much i got to spend would be great and any recommendation on where to find the part even better. Thank you all for your quick responses.

[BEAVER.989]

Check out servicehonda...

http://partsfinder.onlinemicrofiche.com/servicehonda/Honda_OEM/HondaATV.asp

[honda400ex2003]

min is going to be about 400 for the piston, bore maybe, hone, gaskets, and seals. bore about 50 bucks, piston is about 200, gskets 50, valve seals 40, 50 for a cam chain and an extra 10 for tax lol. for some more power while youare at it about 650 would be perfect. that should get you close to what you would be spending with a cam 150, and a nice port and polish is 75 about, other than that some jets for 5 a piece and you should be good to go. steve

[bigdady536]

just check out that site and they are way more expensive then this site. http://partsfinder.onlinemicrofiche.com/cheapcycleparts/Honda_OEM/HondaATV.asp compare the parts in the two listings and it's like 30 percent cheaper with the one i accidentally found.

i've actually heard of people using a little bit of 2 stroke oil when breaking in the motor and stuff. I keep eyeing the mixed gas tank in my garage and I was wondering what it would do if I put a little bit in there haha just curious

[bigdady536]

hey steve
where do i get the bore done i live hear in orlando florida, but where can i get it done. I have seen pistons on ebay for about $75 bucks http://shop.ebay.com/merchant/sledpartsguy_W0QQ_nkwZ400EXQ20pistonQQ_armrsZ1QQ_f romZR10QQ_ipgZ50QQ_sofindtypeZ15QQ_sopZ1and thats the link if anyone could tell me the best one on that and what the difference is between them inlcuding the 440 upgrade that would be great. complete gasket seals for the top end for like $65, including the valve seals i believe here it is let me know if thats what i need. http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&ssPageName=STRK:MEWAX:IT&item=350208967905
The guy i bought if off of has already jetted it and gave me a bunch of jets to change it when ever i wanted. please let me know other than what i listed above i might be needing and if any of the stuff i listed above is what i need. thanks so much everyone

[bigdady536]

http://cgi.ebay.com/ebaymotors/Honda-TRX-400EX-1999-2007-030-Bore-Piston-Kit-NEW_W0QQcmdZViewItemQQ_trkparmsZ65Q3a1Q7c66Q3a2Q7c 39Q3a1Q7c293Q3a1Q7c294Q3a50QQ_trksidZp3911Q2ec0Q2e m14QQhashZitem51897642a4QQitemZ350198579876QQptZMo torsQ5fATVQ5fPartsQ5fAccessories
this is the site for the piston is it good or not, please let me know thanks Mike

[bigdady536]

with regards to the first listing when i take the top end apart what will i most likely see as a result of what the problem is. when a part is bad you can usualy see the ware and tare so what am i most likely looking for. How will i know if the existing parts are still good. Like with a cam chain how can you tell if it is bad or good still. let me know thanks Mike

[BEAVER.989]

You'll probably notice the rings and/or sleeve are worn or scratched. As for the timing chain, they're notoriously weak and are usually changed every time the engine is taken apart, from what I understand. Replace it with a CRF450 chain, much stronger and cheaper, as well.

[bigdady536]

are you sure you can put a crf450 timing chain in a 2005 400ex did not find any results stating it would fit or anything

[BEAVER.989]

Yep. Just search timing chain and you'll find a bunch of threads on this.

Heres one, for example...

http://www.exriders.com/vbb/showthread.php?s=&threadid=388916&highlight=timing+chain

[honda400ex2003]

to the boring post, i got mine done at a machine shop that does atv stuff. i would go talk to a dealer or some other high performance place. motorcycle guys would know where to get stuff bored too. The 450 cam chain will work just fine it is the same length but wider so it will be like an hd chain. you should be able to tell how wore out it is from looking at the guides and the tensioner. lock the tensioner before you take it off to see how far in it is. steve

[aDviSol2y]

The very first thing you should do is get a clymer service manual. Read it, and you will be able to do most everything yourself, if you have the right tools.