HEADS UP!!!

Site upgrade in progress... Core site functions are working, but some non-critical features/functions will be temporarily unavailable while we work to restore them over the next couple of weeks.

Please post any bugs you encounter, but before you do, check to see if it's already listed.

Thanks for your patience while we work to improve the community.

Sign in to follow this  
Followers 0
Bailey7

09 YZ450F Won't start - kickstart wont move!! HELP!

15 posts in this topic

I just got the bike last week, changed oil/filter and air filter everything was good. Took the bike out today to a pit where the sand is pretty fine. Ran perfect all day (2-3hrs) then last ride of the day the bike just shut off. Kickstart wouldnt move, I kicked very hard and it went all the way down but sounded like a knocking the motor so i never tried again. I was driving the bike a little hard, and also jumping it. Just read then on another thread that the breather hose is in a bad place. Any suggestions on what is wrong with the bike and what steps i should take, im going out now to look at my oil filter to check for metal particles. I will probably take as much as the motor apart if i need too and hopefully not have to bring it to a mechanic. PLEASE HELP! Any suggestions ?

Share this post


Link to post
Share on other sites

Anytime an engine locks you need to pull it apart and see what went wrong.

Don't try and start it again you could just end up doing a lot more damage.

Share this post


Link to post
Share on other sites

yah i am not kicking it at all, just once or twice when it first happened, it the kickstart would go down but i would literally have to kick it as hard as i could so i stopped. i hauled the plug out and still the same thing, i checked the oil filter and it was full of little bits of sand, and some little tiny tiny metal shavings. so i should start taking apart the motor ?

Share this post


Link to post
Share on other sites
Cam chain skipped teeth, out of time...Betcha.

Hi, a friend had this problem, the bike was rebuilt with new cam chain and tensioner and about a mile into its first ride we think its gone it again. Is it a real common thing for the 450's? And is there a cure?

Paul

Share this post


Link to post
Share on other sites

No, it's just that it's almost the only thing that ever goes wrong.

If the bike was just rebuilt, my money is on the cam caps having been torqued wrong, or a bad oil pump that wasn't corrected first time through.

Share this post


Link to post
Share on other sites
Hi, a friend had this problem, the bike was rebuilt with new cam chain and tensioner and about a mile into its first ride we think its gone it again. Is it a real common thing for the 450's? And is there a cure?

Exactly what GR said...No, I don't think that would be the issue with a new rebuild...It's a common problem because most people don't replace the cam chain soon enough, and it stretches easily just like a stock drive chain would...I also suspect that the cam chain tensioner has a really cheap spring inside of it, and that after a few super hot heat cycles it looses it's "springyness", kind of like what happens to clutch springs after a while (kind of bad example since they are 100 times beefier, but you get my point)...

This problem happened to me with only about 20 hours on my 07, but since the tensioner and chain have been replaced ALL has been fine (although it's been 60+ hours on it since then, so it's time to do it again)...

Share this post


Link to post
Share on other sites

Alright so when I took my carb off last night and looked in at the intake valves, center and the right look fine but could be bent from what i can see, the left valve stem cracked right off with a peice of the valve sticking up next to it, i should take a picture when i go to haul the motor apart :ride:

It is possible that it was the timing chain since there is probably about 15 hrs maybe less on the bike since the last full (bottom to top rebuild),

Im hoping i just need new valves and piston.

Share this post


Link to post
Share on other sites
Goose,

Where do you get your chains/tensioners and about how much?

Thanks,

Subby

Just replaced it with stock, and haven't had another issue with it...:ride:

Share this post


Link to post
Share on other sites
Alright so when I took my carb off last night and looked in at the intake valves, center and the right look fine but could be bent from what i can see, the left valve stem cracked right off with a peice of the valve sticking up next to it, i should take a picture when i go to haul the motor apart :smirk:

It is possible that it was the timing chain since there is probably about 15 hrs maybe less on the bike since the last full (bottom to top rebuild),

Im hoping i just need new valves and piston.

Hey Bailey, just checking to see if there's any updates...

How's it going?

Share this post


Link to post
Share on other sites

I've seen 2 yz's...an 06 and an 08 that the sprocket actually slipped on the cam....weird. With all timing marks lined up proper, intake cam lobes were pointing almost straight up.

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!


Register a new account

Sign in

Already have an account? Sign in here.


Sign In Now
Sign in to follow this  
Followers 0