ok its broke so what broke????

[low4door]

ok so i got a 2000 400ex it ran super noisy but from what i was told it has all different kinda stuff done to it so i donno if it was suppose to sound like that. i'm new to the atv word and i have no idea what happened so maybe you guys can help. got the quad rode it for a day and a half and the bearing carrier needed changed. got it install today rode it aroud for half the day was puttin through a field at resonable rpms and boom. wasnt real loud sounded like a little backfire but stopped running. now when i turn it over it wont start and i'm getting no back pressure from the exhaust. i'm thinking my connecting rod broke.any ideas and suggestions would be great.

[beags86]

does it turn over? you say it turns over, but what does it sound like when you do so? any clunking, grinding, banging? does it have compression?


what else do you know about the quad? help us a bit more with some more info and we can help you better.

i wouldn't be as worried about the rod as the valves, or timing chain.

[low4door]

yes it does turn over but it spins fast. i did a little investigateing and i took the intake tube off the carb and put my hand over it to see if the piston was even moveing. sure enough i can feel the pressure of the piston moving when i crank it. an no no noises clanking grinding nothin. it just spins fast. perhaps timeing chane broke? doesnt feel like the valvs are opening and closeing. and if they were wouldnt i get pressure from the exhaust when i crank it?

[low4door]

o and from what i'm told it's got a 440 big bore kit with stage 2 hotcams i believe. the guy i got it from said the whole motor had been run through for raceing so i have no clue what kinda parts have been put into this thing.

[beags86]

sounds like timing chain, looks like you need to start pulling it part. if i am wrong...well you'll find the problem..

[CJM]

timing chain probably, or the tensioner which go hand in hand usually. My firend broke 2 tensioners before we figured the chain was stretched too.

[low4door]

thanks for the help guys guess ill break it down and let ya know how the progress goes

[MO-EX-RIDER]

i have one in my garage right now with the exact same issue and it died the same way. turns over but feels like it has no compression tore it down and valves look horrible and the 450r timing chain is stretched - i also noticed a lot more wear on this guys cam than i have ever seen??

[low4door]

ok so im lookin for a new chain and tensioner anyone know what brand direction i should go with. i mean i found a cheap chain but i dont wanna have to tear it back down in a month cause the chane is stretched or even worse breaks again. any prefrences?

[CJM]

2000 honda crf450 chain will fit and its only 50 bones.

Tensioner can only be bought at dealer.

While you have it apart it would be a good idea to check the valves and the cam for wear.

Also while your at it, would be a good idea to verify the tensioner is bad. Take the little screw out of it and take a small screwdriver stick it in there and turn it and see if the thing springs back-if it doesnt its shot.