Jump to content
Sign in to follow this  

2014 KX450F Won't Start?!

Recommended Posts

I have a 2014 KX450F that is bone stock and has 12.5 hours on it. I don't race it, just practice ride the moto tracks and trail ride in the mountains. Last time I rode about 3 weeks ago the bike ran great - just like a new bike should. It sat for about 3 weeks while I moved so last night I changed the air filter with a clean Twin Air and I was going to change the oil but the bike would not start! I kicked and kicked but it never even sputtered. I tried cracking the throttle while kicking and all it did was back fire. I pulled the spark plug out and it looked nasty (see pic). I haven't tried a new plug yet but what on earth would cause the plug to look like this after only 12.5 hours?! Also, why won't she start all of a sudden?! Thanks!

spark plug 1.JPG

Share this post


Link to post
Share on other sites

The pic is not the best but, my first thought is pre-ignition or detonation.  It appears from the pic the body of the plug (where the threads are) has crater like shapes.  That is from the detonation betting it up.  There is a chance the piston and head looks the same.  Check valve lash, and try again.  Then report back.

Share this post


Link to post
Share on other sites

looks like a lot of corrosion on the plug,I would check the plug cap.It may have been running lean,did you hear any knocking sounds under load or pinging?

Edited by etuke

Share this post


Link to post
Share on other sites

The pic is not the best but, my first thought is pre-ignition or detonation.  It appears from the pic the body of the plug (where the threads are) has crater like shapes.  That is from the detonation betting it up.  There is a chance the piston and head looks the same.  Check valve lash, and try again.  Then report back.

Yeah sorry about the pic quality, it was hard to get focused on the plug with my phone. Do you think detonation or pre-ignition could be caused by high octane fuel? I am using 91 pump now but previously I ran about 4 gallons of VP 110 leaded through it. I really hope the cylinder, piston and head arent' messed up. I will check it out with a bore scope though. Do you really think I should need to check vavle lash after only 12.5 hours? Also now that I think about it, I ran nothing but VP 110 through my 07 KX450 and never had a problem. Thanks for the help

 

looks like a lot of corrosion on the plug,I would check the plug cap.It may have been running lean,did you hear any knocking sounds under load or pinging?

No, I haven't heard any unusual noises at all. The bike has always ran great.

Share this post


Link to post
Share on other sites

I don't get why people do this, the bike is not designed to run 110 octane fuel. First off your wasting your money, there's no advantage to running it. Second, it's going to run hotter and it's going to burn the fuel different.

 

Put a new plug in and run 91-93 octane fuel.

 

Remember this: High octane fuel does not hold more energy per say. It just allows builders run higher pressures and run tighter tolerances to burn said fuel more precisely and extract all the energy.

Share this post


Link to post
Share on other sites

The motor is fine. Plug looks dry, so its probably lack of fuel. Do a quick spark check. Then check fuel system.

Share this post


Link to post
Share on other sites

I don't get why people do this, the bike is not designed to run 110 octane fuel. First off your wasting your money, there's no advantage to running it. Second, it's going to run hotter and it's going to burn the fuel different.

 

Put a new plug in and run 91-93 octane fuel.

 

Remember this: High octane fuel does not hold more energy per say. It just allows builders run higher pressures and run tighter tolerances to burn said fuel more precisely and extract all the energy.

My '13 detonated on pump fuel on hot days early on so I've been mixing 1 gallon pump 91 with 4 gallons Sunoco 110 since about 10rs. 75 hrs on it now and when I pulled the head at 50 hrs for a top end it all looked great.

  • Like 1

Share this post


Link to post
Share on other sites

My '13 detonated on pump fuel on hot days early on so I've been mixing 1 gallon pump 91 with 4 gallons Sunoco 110 since about 10rs. 75 hrs on it now and when I pulled the head at 50 hrs for a top end it all looked great.

Yup and you're wasting $$, mix 1 gallon 110 with 4 gallons pump and you'll get the same effect.

 

I'm sure your bike benefited from a little octane boost. But, keep this in mind at 1(91) to 4(110) mix your final octane is 95. Your bike is not benefiting from anything above that. Right now your running a final of 106 octane.

Share this post


Link to post
Share on other sites

Yup and you're wasting $$, mix 1 gallon 110 with 4 gallons pump and you'll get the same effect.

 

I'm sure your bike benefited from a little octane boost. But, keep this in mind at 1(91) to 4(110) mix your final octane is 95. Your bike is not benefiting from anything above that. Right now your running a final of 106 octane.

Whoops, my bad! This is actually what I do, I reversed it in my post for some reason. I use 4 gallons *pump* premium with 1 gallon 110 octane. Just enough to get the octane boost and kill the detonation. Not sure why I was thinking I was doing it the opposite. :)

 

I haven't ridden in 6 weeks (too much work) so I am forgetting wtf I do!

Edited by skthom2320

Share this post


Link to post
Share on other sites

I looked at the piston and cylinder with my bore scope and all looked good. I slapped a new spark plug in it and bam! Fired up second kick. Still not sure why the plug would be bad after just 12.5 hours tho?

Share this post


Link to post
Share on other sites

I looked at the piston and cylinder with my bore scope and all looked good. I slapped a new spark plug in it and bam! Fired up second kick. Still not sure why the plug would be bad after just 12.5 hours tho?

 

Good to know you got it running.

 

Take a few more pics of that old plug and let us see them.  I think I might even do a plug chop on that old plug to see if maybe the insulator is cracked.  The gap or anything near the gap deff. doesn't look to be the issue.

 

If very well may be the fuel you are running.  How long does the fuel sit before using it?  Are you storing it in a steel can?  There are a lot of variables with the fuel that could be causing this.  These newer 4-strokes are running on the ragged edge with combustion pressures in terms of being able to run pump gas with all the trash additives they are putting in.  Then the longer you leave it sit not stored properly the worse it becomes.  You ever notice any time you buy a quality race fuel it's always in a steel container?  That's not just because the gov. says it needs to be.

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  

×
×
  • Create New...