Jump to content
Sign in to follow this  

Won't start when hot?

Recommended Posts

I have a yz250 and it won't always restart when it's hot. Last time it wouldn't restart I was way out on a beach and pushing that thing through deep sand was not fun. What is the common cause for that? I'm hoping it's not the coil. It runs really good as long as you don't kill it and need to restart it!

Share this post


Link to post
Share on other sites

do you have spark when its hot?

pull the plug when its hot & check if it sparks when you kick it. (you will have to ground it to some metal)

Share this post


Link to post
Share on other sites

I have not checked that yet. There is a little story behind why. I had just got rid of my '07 yz450f and as you probably know the spark plugs require a different size wrench. So there I was out in the middle of no where with my usual 4-stroke tools and a spare plug that I couldn't change! Luckily after it sat for about an hour and about 400 kicks later it started.

Will the checking for spark when it's hot tell me if the coil is bad?

Share this post


Link to post
Share on other sites

If it doesn't start after a few kicks, turn the gas off. Hold it wide open and kick it until it starts.

Don't forget to turn the gas back on. :banana:

Share this post


Link to post
Share on other sites

does it feel like it has good compression? A worn out top end will cause that as well.

Share this post


Link to post
Share on other sites
I have not checked that yet. There is a little story behind why. I had just got rid of my '07 yz450f and as you probably know the spark plugs require a different size wrench. So there I was out in the middle of no where with my usual 4-stroke tools and a spare plug that I couldn't change! Luckily after it sat for about an hour and about 400 kicks later it started.

Will the checking for spark when it's hot tell me if the coil is bad?

it'll tell you if you are getting spark when its hot.

if you aren't you can go from there (coil)

also sounds like you might just be flooding it somehow...

id check spark first.

Share this post


Link to post
Share on other sites

If there is no spark when it is hot, it's likely the stator.

Share this post


Link to post
Share on other sites

When you say restart, did you kill the bike then try to restart it? If it was an ignition problem that caused the stator (or another part of the ignition) to stop working when the bike is hot then wouldnt the bike be running fine then then all of the sudden turn off by itself?

Share this post


Link to post
Share on other sites

I had turned the bike off to call my friends and see where they were at. We got separated on the trails. First thing I did when it wouldn't restart was to turn off the gas. I kicked it until my my leg couldn't kick it anymore.

Share this post


Link to post
Share on other sites

Why would the stator suddenly produce a voltage under hot conditions (engine is running) and then not when the engine is the exact same temp, but off??? :banana:

Same with the coil.

It doesn't make sense that heat is a factor cause it's already hot when the engine was running, you'd think as soon as it does get hot the device would stop working and the engine would stall.

Share this post


Link to post
Share on other sites
I had turned the bike off to call my friends and see where they were at. We got separated on the trails. First thing I did when it wouldn't restart was to turn off the gas. I kicked it until my my leg couldn't kick it anymore.

when is the last time you did a top end on the bike?

Share this post


Link to post
Share on other sites
when is the last time you did a top end on the bike?

I just traded for the bike a few weeks ago, but I was told it had around 15 hours on the top end. It starts easy when cold and runs VERY strong so I assume he was honest with me. I came off of an '07 yz450f and I consider this 250 to be a strong runner. I guess I could do a compression check.

Share this post


Link to post
Share on other sites

Try going in a half a turn on your air screw.Also could be reeds.Crack the throtle a 1/4 to a 1/2 when kicking.Next would be jetting and or rings.Maybe float bowl height?Good luck.

Share this post


Link to post
Share on other sites

Took the bike on a good long hard ride yesterday and had no problem restarting it. Never had to kick it more than once or twice. I put in some gas from a different gas station and mixed it a little bit more lean. Ran great all day. It does stall quite a bit easier than my 07 yz450f did. I need to do a few little mods to make it more trail friendly. Probably go to a 13/52 sprocket setup, and add a flywheel weight.

Also it takes a lot of effort to work that clutch. Arm pump was a serious problem on the technical trails. My front brake also was just barely working by the end of the ride. I'm going to check that out today.

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

Reply with:

Sign in to follow this  

×