I Think I'm Screwed!!

[Misfit138]

I was at the track today and was just messin around when my 400ex started knocking really bad.does anyone know what this could be? It knocks really bad,but it still runs smooth.The engine shakes so bad it shakes the whole quad but it don't sputter or miss. Also no smoke just a hell of a knock!!!What could it be????:mad:

[vAnS_77]

it's that 440 kicking in :D

[drew416ex]

It could have possibly jumped timing causing the valves to hit the piston. mine did it and still ran smooth, but knocked really bad

[Misfit138]

What damage can that do????:eek:

[rideracelivemx7]

if its shaking the engine then its mostlikely a soun bearing. and the crank is getting thrown out of wack. spinning that fast the slightest imperfection will throw a bearing and cause some nasty vibrations. you'd know damn well if it were timing. it would barley run. and pop and puff and back fire everywere if it had jumped a tooth cuasing off timing. but is the vibration coming from the lowerend or the top end. ill put my money on it that its a bearing problem

[REPOMAN]

mine did that same noise and i dropped 2 valves on the top of my piston. i am now going to buy a 450r

[UNBROKEN]

man i thoght that 440 was jus breaking in :blah:

[drew416ex]

Originally posted by rideracelivemx7
you'd know damn well if it were timing. it would barley run. and pop and puff and back fire everywere if it had jumped a tooth cuasing off timing. but is the vibration coming from the lowerend or the top end. ill put my money on it that its a bearing problem

Like I said, mine did the same thing, it ran fine, just some vibration and loud knocking and it was 1 tooth off on timing. It didnt pop and puff and backfire, it just knocked really loud.

[Misfit138]

was it hard to fix?

[rideracelivemx7]

not at all timing is really easy to fix. you must have gotten lucky. when ever ive had off timing the beast would barley start up. then again ive never had the timing off on the 440. ive had it off on a big bore xr 70 that ive done. ohh did it run bad lol REPOMAN. same thing happened to me last week dude. it sucked lol luckily i shut the bike off the second they broke off and saved my walls.how did yours end up

[Misfit138]

I think I have found the problem guys. I torn into my motor and found that my timing chain was really really loose. The guys at dealership told me that was the problem and the timing chain was hitting in the motor and it probely did not hurt anything and that I could adjust it some how but i just can't figure it out.Do any of you guys know how to do this?? If so please help!!!

[drew416ex]

It should be self adjusting. So either the chain is really stretched or the tensioner is bad.

[Misfit138]

so should i try a new chain??how is that to install?

[drew416ex]

Its not hard if you have the tools. A manual would also help out so you know exactly whats involved. And also check the tensioner. It could be hung up or something.

[alex10]

It sounds like your chain tensioner broke. Take it out and see.

[rideracelivemx7]

never heard of a tentioner breaking? the chains in the 400s are notorious for streching out far to much. replacing the cahin was fun to me. you have to pull the clutch and basket. and a gear. only 2 bolts just get a impact gun and it rips em right off with no problem. and 2 gears slip off a splined shaft and the cam chain gear slides off. its easy. not much to that side of the case. go to **************.com awsome. they overnight there parts. and i got the cahin for 50 i think. heavy duty. double the thickness. great deal.

[gojk]

Originally posted by rideracelivemx7
never heard of a tentioner breaking? the chains in the 400s are notorious for streching out far to much. replacing the cahin was fun to me. you have to pull the clutch and basket. and a gear. only 2 bolts just get a impact gun and it rips em right off with no problem. and 2 gears slip off a splined shaft and the cam chain gear slides off. its easy. not much to that side of the case. go to **************.com awsome. they overnight there parts. and i got the cahin for 50 i think. heavy duty. double the thickness. great deal.

I actually just had a tensioner break. When it broke, the cam chain flew off and luckily binding the engine, otherwise the piston would have hit the valves and the cost would have been much greater.

A cam chain is really easy to replace. Make sure to get the crf chain instead of the ex OEM chain as it is much stronger and it is also much cheaper. To replace it, just pull the valve cover, take the tensioner off, pull the clutch side cover, the clutch, and the oil pump. Thread the new chain through and put it on the gears on both ends. Sounds like a lot, but it really can be done in an hour or two tops.

[Brauap]

swingarm bearings? Mine are bad and they clonk real loud.. and rock my 400 too.. unless your 100% sure its in the engine...

[Misfit138]

yep 110% sure