'08 450 with 47 hours = locked up :(

[swaldrop]

OK. As the title reads, my '08 450 just gave up the ghost about an hour ago. I was coming into a corner when it just died. When I went to kick it over, there was very little compression for about one and a half kicks (along with a few weird clickity-clacks), then nothing. Now it won't budge and I don't really want to force the issue until I can get in there and check it out.

My maintenance routine is pretty nailed down...

- New Rotella T oil every 2 rides (2 to 3 hours) with an OEM oil filter every other oil change.

- I change the air filer every ride without fail.

- I check the coolant often and run Maxima Coolanol/Cool-aide 50/50.

Now the problem... I have never cracked open a 4 stroke before. The most extensive work I have done was a valve check on one of my old 250Fs.

The only thing I know right now is that the kick starter won't move. I also checked the coolant level just now and while it is full, it does look dark like maybe there is some oil in it. However, when I checked it earlier today it was clean.

I am going to eat dinner and then drain the fluids. Any wisdom on where to go first would be much appreciated.

Thanks

Steve

[swaldrop]

I just got the oil and coolant out and they both looked fine. The coolant (to the best of my knowledge) didn't have any oil in it. With a 50/50 of Cool-Aide (bright pink) and Coolanol (bright green) the result will be a dark purple/brown color.

OK, any time anyone would like to chime in and help out, I'm all ears. I will be refreshing this thread every time I get a different part off in hopes of someone out there with some much needed direction ?

Thanks

[JSanfilippo]

OK. As the title reads, my '08 450 just gave up the ghost about an hour ago. I was coming into a corner when it just died. When I went to kick it over, there was very little compression for about one and a half kicks (along with a few weird clickity-clacks), then nothing. Now it won't budge and I don't really want to force the issue until I can get in there and check it out.

Any chance it got hung up on the compression stroke? (i.e. the decomp pin isn't opening the exhaust valve) My WR 450f does that sometimes if I stall coming out of a turn and it takes alot of effort to get the engine past TDC. The first time it did it was actually in the garage the day I bought it and I was scared shitless because I thought my new toy had just seized.

Put it in 2nd or 3rd and rock it back and forth a few times and give it a shot. Fill the oil and coolant of course ?

[ThumperKid250F]

i really dont no what to tell besides pull the top end off and take a look at your piston valves and such..

my 2006 yz 450 blew up on this ice this year. the wrist pin snaped and made the piston go all over. i cracked my cilinder, piston was distroyed, crank was wrecked , but the good news is that the piston just touched my valves so all i need to do is just replaced all the valves springs and such. no new head:thumbsup:..

so what i would do is just take the motor out of the frame and put it on a good bench and take the motor apart there. instead of you trying to do everything in the frame of the bike.

good luck and let us no

[ThumperKid250F]

Any chance it got hung up on the compression stroke? (i.e. the decomp pin isn't opening the exhaust valve) My WR 450f does that sometimes if I stall coming out of a turn and it takes alot of effort to get the engine past TDC. The first time it did it was actually in the garage the day I bought it and I was scared shitless because I thought my new toy had just seized.

Put it in 2nd or 3rd and rock it back and forth a few times and give it a shot. Fill the oil and coolant of course ?

i really dont think it would get hung up on a compression stroke when he was coming into the corner with the bike running...

[swaldrop]

Any chance it got hung up on the compression stroke? (i.e. the decomp pin isn't opening the exhaust valve) My WR 450f does that sometimes if I stall coming out of a turn and it takes alot of effort to get the engine past TDC. The first time it did it was actually in the garage the day I bought it and I was scared shitless because I thought my new toy had just seized.

Put it in 2nd or 3rd and rock it back and forth a few times and give it a shot. Fill the oil and coolant of course

I wish I could say that was a possibility, but it is locked up tight ?

[swaldrop]

i really dont no what to tell besides pull the top end off and take a look at your piston valves and such..

my 2006 yz 450 blew up on this ice this year. the wrist pin snaped and made the piston go all over. i cracked my cilinder, piston was distroyed, crank was wrecked , but the good news is that the piston just touched my valves so all i need to do is just replaced all the valves springs and such. no new head:thumbsup:..

so what i would do is just take the motor out of the frame and put it on a good bench and take the motor apart there. instead of you trying to do everything in the frame of the bike.

good luck and let us no

Do you think it's really necessary to pull the motor completely?

[KAS]

You're probably screwed, just like me.

My '07 had a valve break (its got around 40 hours on it) a few weekends ago.

It needed a new piston, cylinder, head, all 5 valves and other misc valve train parts.

You don't need to pull the motor to tear it down.

[sparkyz]

I would start by pulling the valve cover, if you need to go deeper than that you might make life a little easier on yourself by removing the engine. Pull the valve cover and let us know how it looks.

[ThumperKid250F]

Do you think it's really necessary to pull the motor completely?

no its not necessary but it does make things easy. i would rather spend 30min taking the motor out and working on a clean bench then working with it in the bike..

[alleycat50]

Can you put the bike in a high gear and move the rear wheel? Could just be the kick start hung up.

I know that it died in a corner and you could kick it over, and it felt like no compression.It is an easy check that could save some time.Unlikely,but you have to start at the basics.

This is my first post,and the first thread that I have read.I just purchased a 2008 yz450.you are scaring me!?

[swaldrop]

I decided to pull the motor... It's taking longer than 30 minutes...

[swaldrop]

motor's out. I am going to start with the head and work my way down. Other than reading the manual, any tips or tricks on what to watch out for?

[todds924]

motor's out. I am going to start with the head and work my way down. Other than reading the manual, any tips or tricks on what to watch out for?

Check things out as you work your way down. Check the cams for any sign of seizure, remove the head and the motor will start telling the story. maybe the motor jumped time? How are the intake and exhaust cam lobes oriented with each other? Is the cylinder easy to remove or is the piston stuck in the cylinder. once you get the cylinder off, How does the rod and bearing look. Are your main bearings seized???? It should all become apparent once you start tearing it down. It is all very straight forward,,,,the book explains everything and you should have no problems.

[Beaz]

Any chance it got hung up on the compression stroke? (i.e. the decomp pin isn't opening the exhaust valve) My WR 450f does that sometimes if I stall coming out of a turn and it takes alot of effort to get the engine past TDC. The first time it did it was actually in the garage the day I bought it and I was scared shitless because I thought my new toy had just seized.

Put it in 2nd or 3rd and rock it back and forth a few times and give it a shot. Fill the oil and coolant of course ?

My 08 yz450 does that if i come into a corner and lug it to much it will stall then its hard to kick for a sec then it goes like normal

[swaldrop]

Couple things so far...

The end of the spark plug is smashed a bit and the ceramic was broken. The top of the piston hit the spark plug for sure.

The motor will not got to TDC so I am removing the cams and such without having it in that position.

removing the cams now...

[motoclay]

I bet it dropped a valve. Thats why the sparky is smashed. and thats why u were able to move the kicker a little further. U can t move it now cuz the valve tulip is wedged between the head and piston. When u get it all apart, make damn sure the crank isnt bent or damaged, all that force had to go somewhere, the head took some, but i guarantee that crank took a hit too, just make sure u check it all out, or u will be back here REAL soon. Get ALL the metal out too, thoroughness is key to a good rebuild.

[motoclay]

Blew up a Honda like this few years back, pullin a hill, valved dropped, super damage!!

[KAS]

I bet it dropped a valve. Thats why the sparky is smashed. and thats why u were able to move the kicker a little further. U can t move it now cuz the valve tulip is wedged between the head and piston. When u get it all apart, make damn sure the crank isnt bent or damaged, all that force had to go somewhere, the head took some, but i guarantee that crank took a hit too, just make sure u check it all out, or u will be back here REAL soon. Get ALL the metal out too, thoroughness is key to a good rebuild.

Bingo. You've got waaaay more problems than the smashed spark plug.

[motoclay]

? yeah, haha, hes def. got some further damage!