Need Help - 08 YZ450F Question

[difava]

I have a question for anyone with an 08 yz450f, and I am looking for help/insight. I have a brand new 08 yz450f, bought from a dealership, and it has less then 10 hrs on it, barely broken in. The other day I was lettin my bike run to warm it up, moved it, shut it off, then started it back up and let it run some more. I held it a lil over idle, maybe an 8th of turn at most. I then noticed a small puddle of coolant coming from the overflow tube. I shut it off and let it cool then checked my radiator. The level is a lil lower then the neck of the cap and the manual says it should be at the bottom of the neck. Now this is my first bike and not sure if this is normal for this bike or if I have a problem or what. Kind of confused to why this is happening. It doesnt happen every time I ride the bike either, this is the second time I noticed some overflow. Any ideas???

Any help here will be appreciated.

[lrrs313]

Sounds like the motor just got hot. My YZ is VERY cold blooded; it refuses to run until the motor is quite warm. That being said, the bikes create a lot of heat and rely heavily on moving air for cooling. They will overheat if left on the stand at idle for too long.

[difava]

Yeah mines tough to get running cold too. It was running for maybe 30 seconds tops on the stand before I noticed the puddle. Just got me a lil nervous because the last thing I need is to find out I overheated it yanno?

[lrrs313]

Yeah, I wouldn't worry too much about it. I would stick to just letting it idle to warm up, though. Could always get a radiator cap that runs a slightly higher pressure.

[difava]

Good idea, I dont want to have to worry about it riding it. Has your bike ever taken, lets say, 20 kicks to start after being warmed up? I was riding it, stopped for a min, then it would not start and I was kicking the shit out of it...

[LaRNZ]

Kick it with authority u pussy

[lrrs313]

Use the hot start. My bike starts within the first 3 kicks, basically every time. Remember not to twist the throttle when trying to start it, especially when it's hot. I take my hand off the throttle and put it on the master cylinder to make sure. And make sure you're giving it full kicks. With a four stroke it's not how hard you kick it, it's all about spinning the motor as many times as possible with that one kick.

Have you put an aftermarket exhaust on it? If so, going one size richer on the main jet will help a lot. The bike came a little on the lean side, and getting rid of the stock silencer makes a big difference in the way the bike breathes.

[R7]

I never let my YZ run at idle for more than 20-30 seconds. With a cold start and using the choke, the engine builds heat FAST!
If your bike is hard to get/keep running when it's cold, it may be running lean. With the stock jetting, it is lean. I have a 170 main in mine with the standard pilot, neadle raised one clip and it runs pretty good. Check the pilot jet, the holes are so small, they gum up quick if the bike isn't used much.

I also keep the antifreeze level a bit on the low side, just enough to cover the fins in the radiator.

As for starting hot, I've had mine take a dozen kicks to start, and what seemed like for no reason...not after a crash or something.
A trick that works on mine, which is against what everyone else says...pull the hot start lever, give it a quick 1/4 turn twist of the throttle, and a swift kick. Why it works, I have no idea but it does on mine!

Oh yeah...

[difava]

Use the hot start. My bike starts within the first 3 kicks, basically every time. Remember not to twist the throttle when trying to start it, especially when it's hot. I take my hand off the throttle and put it on the master cylinder to make sure. And make sure you're giving it full kicks. With a four stroke it's not how hard you kick it, it's all about spinning the motor as many times as possible with that one kick.

Have you put an aftermarket exhaust on it? If so, going one size richer on the main jet will help a lot. The bike came a little on the lean side, and getting rid of the stock silencer makes a big difference in the way the bike breathes.

Yeah I havent used the hot start that many times since its in such an awkward position for me personally, and yeah I read up not to twist the throttle.

No exhaust yet, Im thinkin about it but I kinda like how the shorty is compared to aftermarkets, Ill have to work on getting one.

[difava]

I never let my YZ run at idle for more than 20-30 seconds. With a cold start and using the choke, the engine builds heat FAST!
If your bike is hard to get/keep running when it's cold, it may be running lean. With the stock jetting, it is lean. I have a 170 main in mine with the standard pilot, neadle raised one clip and it runs pretty good. Check the pilot jet, the holes are so small, they gum up quick if the bike isn't used much.

I also keep the antifreeze level a bit on the low side, just enough to cover the fins in the radiator.

As for starting hot, I've had mine take a dozen kicks to start, and what seemed like for no reason...not after a crash or something.
A trick that works on mine, which is against what everyone else says...pull the hot start lever, give it a quick 1/4 turn twist of the throttle, and a swift kick. Why it works, I have no idea but it does on mine!

Oh yeah...

So your telling me that after a 30 seconds of running its ready to go? I woulda thought maybe a little more time than that, I feel like it took awhile for my bike to warm up. I havent changed the jets but I was searching around to see what people put in to get the best results but everyone was saying different things due to elevation and all that shit. Ill have to check out my jets and see what I can do.

With the water level like that youve never had a problem?

Everyone was saying NOT to do that, but also a lot of people said they had these little quirks to do after stalling for it to fire back up, havent figured mine out yet. Ill have to see if your method works on mine, hope it does cuz that would sure help me out.

[R7]

So your telling me that after a 30 seconds of running its ready to go? I woulda thought maybe a little more time than that, I feel like it took awhile for my bike to warm up. I havent changed the jets but I was searching around to see what people put in to get the best results but everyone was saying different things due to elevation and all that shit. Ill have to check out my jets and see what I can do.

With the water level like that youve never had a problem?

Everyone was saying NOT to do that, but also a lot of people said they had these little quirks to do after stalling for it to fire back up, havent figured mine out yet. Ill have to see if your method works on mine, hope it does cuz that would sure help me out.

I had mine out yesterday afternoon for a bit, after it's been running for 10-15 seconds on the choke on a cold start, I can shut the choke off and it idles fine.

Never had a problem with the coolant level low