Valves Not Opening And Closing At Right Times

2836 Views 11 Replies 5 Participants Last post by leveldrummer, Mar 16, 2009

coorslightf7

Discussion Starter · Mar 11, 2009

i recently had my 04 yfz450 to a local shop not a atv shop but he does service some atv's but anyway i took my atv there because it wouldnt start and the starter sounded horrible so i had the shop put in a new starter and it still wouldnt start they checked the valve lashing said that was good but somthing was screwy with the head in the valves open and closed when they should be anyone have and ideas what could of went wrong with my atv the shop just said somthing that when they put my piston at top dead center the valves wearnt closed or open whatever there suposed to be when the piston is top dead center and they said as they rolled it over the opened and closed not when they wear suposed too they were stumped so i paid for the starter and now i have my atv thats still broke anyone help me when i try to roll the atv over it bearly wants to roll over sounds like its binding some where??????????????????????????????????

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YFZ450 #69

· #2 · Mar 11, 2009

how handy are you with the tools?

can you put the engine at TDC and take some pics of the cams for us?

from your description, it sounds like the cam chain has skipped a few teeth or the cam gears have spun on the cam....and you'll need to find the cause of this, whether it be a stretched cam chain or a failed tensioner.

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coorslightf7

Discussion Starter · #3 · Mar 11, 2009

QUOTE (YFZ450 #69 @ Mar 11 2009, 02:07 AM) index.php?act=findpost&pid=756401

how handy are you with the tools?

can you put the engine at TDC and take some pics of the cams for us?

from your description, it sounds like the cam chain has skipped a few teeth or the cam gears have spun on the cam....and you'll need to find the cause of this, whether it be a stretched cam chain or a failed tensioner.[/b]

i have another guy that used to work at a local atv dealership as a repairman going to take a look at it right now because i dont trust my self to fix it so im basicly trying to give him some ideas on what might have happened give him somewhere to start looking i know when i took the atv to the local shop to get fixed they said that the tentioner was really tight but i had played with that after the atv had shut off and wouldnt start back up so i didnt figure that anything to do with it but ill run it buy him and see what he thinks and maybe if he has a camera ill have him take a pic but this thing has me puzzled i have thought of so much other stuff then the valves i was thinking crank bearing went and the starter was bad but i replaced the starter and the first local shop i took it too says its somthing to do with the valves because they arent opening and closing like they should be but i think they said that the cams wearnt retarded any or advanced any either so i dont have a clue

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leveldrummer

· #4 · Mar 11, 2009

QUOTE (coorslightf7 @ Mar 11 2009, 05:50 AM) index.php?act=findpost&pid=756402

i have another guy that used to work at a local atv dealership as a repairman going to take a look at it right now because i dont trust my self to fix it so im basicly trying to give him some ideas on what might have happened give him somewhere to start looking i know when i took the atv to the local shop to get fixed they said that the tentioner was really tight but i had played with that after the atv had shut off and wouldnt start back up so i didnt figure that anything to do with it but ill run it buy him and see what he thinks and maybe if he has a camera ill have him take a pic but this thing has me puzzled i have thought of so much other stuff then the valves i was thinking crank bearing went and the starter was bad but i replaced the starter and the first local shop i took it too says its somthing to do with the valves because they arent opening and closing like they should be but i think they said that the cams wearnt retarded any or advanced any either so i dont have a clue[/b]

if that is truly what the shop said, dont ever step foot in there again, that doesnt make any sense what so ever. if the valves are out of timing, that means that the cams are either advanced or retarded, the gear can spin on the cam, which is what 69 said above, if this shop cant logically figure out a way to fix this, i would stay far away from them.

if you set the timing according to the marks on the cams, and lobes arent facing the right directions, then the gears spun, and you need new cams,

if all the timing marks dont line up properly (top dead center, and the cam marks) then the cam/cams jumped teeth, your tensioner might be junk, or the guides could be worn, or your chain is junk, or even the cam sprockets worn etc. it should be pretty easy to figure out for any shop that has taken a head off before.

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davispalmer

· #5 · Mar 11, 2009

Intake cam should look like this when at TDC

exhaust cam should look like this at TDC

Both cams

if yours does not look like this you have problems as started above. if it does look like this adjust your vavles and it should start up, considering everything else is good

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coorslightf7

Discussion Starter · #6 · Mar 11, 2009

QUOTE (Blackedyfz450 @ Mar 11 2009, 12:33 PM) index.php?act=findpost&pid=756509

Intake cam should look like this when at TDC

exhaust cam should look like this at TDC

Both cams

if yours does not look like this you have problems as started above. if it does look like this adjust your vavles and it should start up, considering everything else is good[/b]

you dont have to worry i allready let them know that i would never bring another thing back to there shop i printed everything off that you guys have mentioned to check and will forward what i can to the guy from work i got looking at it that used to work on these things and hopfully he can figure it out and it wont coast me to much to fix and ill be back to riding in no time thanks for all the help guys and if anyone else has any other ideas post um so i can have him check that out too also would it be in my best interest that since im going to have my motor apart to do the cam mod seeings how im pretty sure it hasnt been done yet

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leveldrummer

· #7 · Mar 12, 2009

QUOTE (coorslightf7 @ Mar 11 2009, 06:26 PM) index.php?act=findpost&pid=756591

you dont have to worry i allready let them know that i would never bring another thing back to there shop i printed everything off that you guys have mentioned to check and will forward what i can to the guy from work i got looking at it that used to work on these things and hopfully he can figure it out and it wont coast me to much to fix and ill be back to riding in no time thanks for all the help guys and if anyone else has any other ideas post um so i can have him check that out too also would it be in my best interest that since im going to have my motor apart to do the cam mod seeings how im pretty sure it hasnt been done yet[/b]

get your hands on a service manual, you can download them all over the net for free, buy them on ebay for 5-6 bucks for a pdf, or get one at the stealer ship that is actually paper. it will show how the timing should be set, what clearances everything should have and help you, or him, set the timing and figure this out.

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coorslightf7

Discussion Starter · #8 · Mar 15, 2009

QUOTE (leveldrummer @ Mar 11 2009, 05:00 PM) index.php?act=findpost&pid=756640

get your hands on a service manual, you can download them all over the net for free, buy them on ebay for 5-6 bucks for a pdf, or get one at the stealer ship that is actually paper. it will show how the timing should be set, what clearances everything should have and help you, or him, set the timing and figure this out.[/b]

thanks for everyones help but it wasnt a single problem it was mutiple problems it was rod bearing bad timing chain was strectched so if anyone has a fairly new crank assembly for sale for decent price let me know send me a message

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newblue

· #9 · Mar 15, 2009

what year bike do you have. I have a stock 04 crank for sale

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coorslightf7

Discussion Starter · #10 · Mar 15, 2009

QUOTE (newblue @ Mar 15 2009, 04:27 PM) index.php?act=findpost&pid=758086

what year bike do you have. I have a stock 04 crank for sale[/b]

i have a 04 is it a complete crank assembly

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davispalmer

· #11 · Mar 15, 2009

i got a 07 crank

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leveldrummer

· #12 · Mar 16, 2009

QUOTE (coorslightf7 @ Mar 15 2009, 07:20 PM) index.php?act=findpost&pid=758084

thanks for everyones help but it wasnt a single problem it was mutiple problems it was rod bearing bad timing chain was strectched so if anyone has a fairly new crank assembly for sale for decent price let me know send me a message[/b]

very sorry to hear that man, hope the re-build goes smoothly...

but now that you found the problem, it scares me even more to think the dealership was telling you the valves werent opening and closing at the right times, that should have been something the zero in on rather quickly.

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