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
RyJames

New Member.. Need A Hand Plz.

11 posts in this topic

Hey guys. New member here. My name is Ryan and I ride a 98 YZ 400F.

My bike wouldn't fire up for me a few weeks ago, so I changed the spark plug and that did the trick. I took the bike for a quick run around the yard to be sure everything was fine and I had no issues. I went out again today to see if it'd fire up and the kicker won't budge. The shifter won't even go into Neutral. Next I pulled the plug and the kicker still won't budge. I'm guessing that with it being cold out lately, there's a slight possibility that the cylinder wall could contract against the rings, preventing the piston from moving freely? I've never seen it happen, but just a thought.. Also, could the kicker gear cause this, even though I shut the bike off when everything was fine?

I know this isn't due to any sort of internal engine failure, since it ran fine with the new plug. This bike has excellent compression and runs really strong. The decomp lever is doing nothing for me here either. Any help would be greatly appreciated. Thanks.

Share this post


Link to post
Share on other sites

I went back out and attempted to roll the engine over via the side acess port while holding the decomp lever and with the plug out. Won't budge. I'm baffled, as this bike has always ran really strong and was perfect the last time I shut it off. How could this thing possibly lock up on it's own like this? I'm thinking the piston had to seize against the cylinder wall due to being outside in the cold (No garage)... But in only a few weeks after runing it?

Has anyone here tried pouring a little motor oil in the spark plug hole and letting the bike sit over a day or two to unseize a piston? I'm thinking about trying this. I could really use any help you can offer. This has me baffled!

Ryan.

Share this post


Link to post
Share on other sites

What's in the cooling system? The proper coolant mix, or just water?

If it froze, it could have crushed the cylinder, but you should have seen other evidence, like a bulged hose or radiator, too.

Share this post


Link to post
Share on other sites
What's in the cooling system? The proper coolant mix, or just water?

If it froze, it could have crushed the cylinder, but you should have seen other evidence, like a bulged hose or radiator, too.

Thanks for your reply.

I used 50/50 premix in the cooling system. I've been inspecting the engine and hoses for any sign of damage and everything looks normal and dry. There are no leaking fluids of any kind and everything looks great as far as I can tell. I just sprayed some penetrating oil into the cylinder. I'll lubricate the cylinder bit by bit over the next few days and see if that helps.

The key here is that the shifter won't get out of first gear. I'm no mechanic. I'm trying to figure out what would cause the kicker to stick as well as the gearbox. :excuseme:

Share this post


Link to post
Share on other sites
Thanks for your reply.

The key here is that the shifter won't get out of first gear.

Pull the primary cover and clutch off and check the shift mechanism behind the clutch...Could be a paw is stuck or damaged. still should kick over with the clutch in, though....

Share this post


Link to post
Share on other sites

Thanks. I'll check that out.

Anyone know what could cause both of these problems at the same time? Shifter won't move up or down (stuck in gear) and the Kicker won't budge one bit.

Share this post


Link to post
Share on other sites

Something broken in the trans but I'd think you would've noticed it when it happned. Some tear down may be in order either way.

Share this post


Link to post
Share on other sites

Having just had a 'stuck kickstart' problem on a yz450, can I suggest checking that the camchain hasn't jumped on the cam sprockets? It wouldn't cause both problems, but is easy to check.

No idea on the gear shifter though. Sorry....

Share this post


Link to post
Share on other sites

Thanks fellas. Gonna have it checked out by a local pro since I don't have a garage or the right tools for this job. Once we get it figured out I'll post our findings and maybe it'll help someone in the future.

I appreciate all the replies.

Share this post


Link to post
Share on other sites

Bit of an update for those who are interested.

I talked to a respected shop owner/ex racer a few weeks ago about my little problem. Without looking at the bike for himself, he couldn't think of why the kicker and gear shifter were locked up.. I haven't had any time to do anything with the bike, but, we had a warm day recently. Temps reached +1Celsius so when I got home from work I decided to see if I could get the bike out of gear. I felt a bit of movement in the shifter that I couldn't get since it locked up. After easing it up and down for about 10 seconds, I felt a "click". I was now able to roll the bike in neutral! Decided to try the kicker now. With the plug still OUT of the bike, I pushed down with my hand and down it went! This is so odd. Could there be a crapload of water in my bottom end that is freezing everything up in the colder temps? Temps dropped way down again and the kicker is stuck again. I'm getting it into the local shop for storage and a full service asap. Anyone experience this before?

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