400ex problems

[Tonyw]

ok i started off rebuilding the motor setting the valves and timming off diagrams on the internet now when i choke and try to start the bike it pops and spits like wants to start check compression it perfect i wan thanking it may be out time just need little advise or better guide when come to setting the timeing

[JOEX]

Originally posted by Tonyw
ok i started off rebuilding the motor setting the valves and timming off diagrams on the internet now when i choke and try to start the bike it pops and spits like wants to start check compression it perfect i wan thanking it may be out time just need little advise or better guide when come to setting the timeing
Give some more detailed info regarding what was rebuilt and/or replaced. I have an idea but we need more info.

[matt1106]

i cant believe you would do a project like that without even knowing how to do the timing, its very easy, but i dont feel like typing it all, so sorry, should have brought it to a shop

[Pipeless416]

Originally posted by matt1106
i cant believe you would do a project like that without even knowing how to do the timing, its very easy, but i dont feel like typing it all, so sorry, should have brought it to a shop

you wont last long on this forum. idiot. :mad: anyway, to the original question, im guessing i have the same idea as JOEX, but its impossible to tell without some more details. let us know! ;)

[fastredrider44]

Chances are, you still don't have the timing right yet. But like they said, what all did you do to it.

[tim colston]

Originally posted by matt1106
i cant believe you would do a project like that without even knowing how to do the timing, its very easy, but i dont feel like typing it all, so sorry, should have brought it to a shop

GREAT POST MATT1106 YOU WILL NOT LAST LONG jerk. It may be a timing issue. What did you add to your engine?

[Exrider434]

Originally posted by matt1106
i cant believe you would do a project like that without even knowing how to do the timing, its very easy, but i dont feel like typing it all, so sorry, should have brought it to a shop

I hate people like this, why bother posting something stupid if its not helping?

Id actually like to know how to do the timing as well, It would help me out a ton!!:rolleyes:

[matt1106]

I'll tell you what guys, i'll do a writeup on how to check the timing and how to change it. I just understand why somebody would "rebuild" their motor if they dont even know how to adjust the timing. It should be a lesson learned to him, thats all i'm saying. It's really indepth thats why i didnt explain it, i'll take a few pics and explain the whole thing, sorry to have pissed you guys off

[Pipeless416]

Originally posted by matt1106
I'll tell you what guys, i'll do a writeup on how to check the timing and how to change it. I just understand why somebody would "rebuild" their motor if they dont even know how to adjust the timing. It should be a lesson learned to him, thats all i'm saying. It's really indepth thats why i didnt explain it, i'll take a few pics and explain the whole thing, sorry to have pissed you guys off

the same exact thing could be said about us not understanding why somebody would "post" a reply if they're not trying to help. i'll stand by my first post, idiot. this should be a lesson to you on something as simple as the golden rule.

[matt1106]

That hurts!

[espergre]

I would recommend purchasing a clymer manual if you plan on wrenching on your quad. The book has great pictures and diagrams that help explain how to correctly disassemble and reassemble every part of your ex. They only cost around $20-$30.
The manual will explain how to align the chain and cam while the flywheel is in a certain position while on the non compression stroke. The diagrams will help more than any of our explanations. GOOD LUCK

[matt1106]

You are actually better off to buy the factory manual from honda, they have more pictures and better more specific descriptions, the only thing is they're like $60

[tim colston]

Originally posted by matt1106
You are actually better off to buy the factory manual from honda, they have more pictures and better more specific descriptions, the only thing is they're like $60

Buy a clymer or Haynes manual. much better than the honda. You can find them used all day long on ebay, that is where I got my for 10 bucks shipped.

[matt1106]

That's weird, i hated my haynes one, thats why i got the honda one, maybe its just a matter of what you can understand easier

i have the clymer and they have pictures and its pretty easy to understand

[matt1106]

I dont think i've ever seen one, but i'll probably try one when i pick up a quadracer 250 for my next project, the guys at my local shop say clymer is much better than haynes.

[Tonyw]

well first off im not new to building motors do all my own work on my drag car now for the bike

its all stock i busted a piston small crack so i replaced with wiseco piston ever thang else is stock

i ready little here and there about timing and i looked ever thing over and wrote notes on the timing so i whould know how it went back

i may have gotten it off a little the motor has great compression and it chould be something else causeing the problem that why im here

and got 1 more ? i see were it says not to rotate the motor clock wise if u miss your mark make the full rounds till your back tdc just want to know why that is

[Exrider434]

just bought a new clymer manual today! $33.15 brand new

[JOEX]

I'm not so good with explaining things in detail but this is what I have...

The stock 400ex has a decompression mechanism on the cam along with a small spring and plunger located in a small hole in the head. This has to do with not turning the motor backwards.

If the spring and plunger are not installed the motor wont start.

Looks like this...

[Pipeless416]

thats exactly what was going through my head. when i rebuilt my brothers 400 those things were floating around the garage floor :rolleyes: . luckily i found them. anyway, make sure that first, they're in there, and second, they're not backwards.

[Tonyw]

humm ill have to check how can u tell if there up sidedown and what if iv lost em can u buy from honda

[espergre]

The spring goes in first and then plunger, you can buy replacement parts from your local dealer, around $15 for spring and plunger. Check out www.bikebandit.com They sell oem parts and have detailed schematics available to help find your part and serial #. Much cheaper than dealers.

If you timing chain sprocket is off just one tooth from the timing chain correct position your bike will sputter and not run well, perfect alignment is crucial. GOOD LUCK

[cmaxx]

heres what you do u pull out the plugs in the side of the motor and put the in the small hole and the cam should have lobes down and the lines on the gear sould be flush with the top of the head.if you need more info pm me

[Tonyw]

so at tdc on compression stroke the cam lobes will be faceing down and the mark will line up with the top of the head


Thanks For Ever Ones Help im Get started c what i come up with ill let ever one know how it gose

[Tonyw]

well no luck iv never had so much trouble with a motor

on the flywheel side top hole there 3 marks the last one has T on it i know it way out time now it was spiting backfireing guess ill have to order the book

on the decompresson pin and spraing were is it located n the head only pin i seen were the ones that hold the cam berings in maybe its missing or i over looked it but i look it over good

dose any one have pic of the pin in the head

[tim colston]

seriously tony look on ebay, my clymer is priceless to me. Or put a thread out in the wanted section. Someone who moved up to a 450 may have one lying around.

[espergre]

check out bikebandit.com for a schematic of the cylinder head. It shows where the spring and plunger are located. Here is link to schematic.
http://houseofmotorcycles.bikebandit.com/parts/Honda/TRX400EX+SPORTRAX+400EX/2007/2333659

[espergre]

take a look at this article, it doesnt show how to align flywheel and cam but it does show the plunger location nicely. GOOD LUCK

[Tonyw]

ok thanks ill look it over and im gonna get a book thanks there like 32 bucks off there site

[Tonyw]

Back up and running Thanks Ever one That helped and Lend There Advice

The Problem was the spring and plunger on the cam got new ones now that i know were it gose and fig out the timing there were 2 marks u line up with the head and one on the top

[espergre]

congrats, good work man. glad it worked out