First 4 stroke and new to the forum....


10 replies to this topic
  • renodirtandsnow

Posted June 22, 2009 - 08:49 PM

#1

Hey folks. I have been riding for a long time. But just picked up my first four stroke 2 months ago. 2006 YZ450F. Great bike. I absolutely love it...

Here is my issue...

One weeks ago I took a 60 mile trail ride. Bike was running good for about 35 miles but I could still smell the burning smell. Around the 50 mile mark my bike starting to die on me. Make a long story short I was able to coast down hill back to my house the remaining part of the ride. After I got home with closer inspection I realized my bike had a coolant leak at the pipe coming from the head going back into the left radiator. My bike must have been over heating and cutting out. My bike had about 1/2 the coolant it should have.

I fixed the leak and bike was running great for a few days. But now I have a off idle hesitation and bike will die when I come into corners, stop quickly or coming down a steep grade. I am not sure if my bike getting a little hot would cause these issues...

Bike has tons of power up top and never has an issue once I am moving. But the hesitation and bike dieing has me a little confused.

Any suggestions on what could be causing these symptoms. I live at 5000 feet (Reno, Nevada) but bike has stock jets. But bike runs great with the current jetting.....Plug is light brown and burning great.


I have searched and came up with moving the needle clip, raising idle and turning idle screw in. But I it is just weird that it just started. I realize the warmer weather is causing my bike to run rich. My bike only dies in corners, down hill descents and quick stops. Never in the air when jumping.....

Thanks for the help form the newbie.....

:worthy:

  • renodirtandsnow

Posted June 22, 2009 - 08:53 PM

#2

One other thing the trail I ride I went on was the bumpiest ride I have ever done. I was thinking the whole time If my bike was going to have a problem, this trail will be the perfect spot. Is there any connection, wires, ect that commonly come loose on these bikes?

  • renodirtandsnow

Posted June 22, 2009 - 09:12 PM

#3

Oops double post....

  • grayracer513

Posted June 23, 2009 - 05:46 AM

#4

Trim your idle mixture.

A rich idle causes an engine to die on idle down (dropping to an idle when the throttle is closed quickly), and an increase in temperature causes a rich idle, assuming it was correctly set when it was colder.

http://www.thumperfa.../jetting.htm#PJ
http://www.thumperta...ad.php?t=696672
http://www.thumperta...ad.php?t=327405

The problem is not likely related to the overheating incident.

Be sure you know where this thread is:

http://www.thumperta...ad.php?t=447989

  • renodirtandsnow

Posted June 23, 2009 - 08:14 AM

#5

grayracer thanks for the info and links. By the look of my plug the bike seems to be running good. I will mess with the idle mixture today and see what happens. From what I read if the idle mixture need to be less than 1 turn out or more than 2.5 turns out I need to re jet my bike? Can all the jets be reaches from bottom of the bowl?

Visit the ThumperTalk Store for the lowest prices on motorcycle / ATV parts and accessories - Guaranteed
  • grayracer513

Posted June 23, 2009 - 08:32 AM

#6

  • By the look of my plug the bike seems to be running good.
  • From what I read if the idle mixture need to be less than 1 turn out or more than 2.5 turns out I need to re jet my bike?
  • Can all the jets be reaches from bottom of the bowl?

  • The plug can be an indicator of the general condition of things, but not the jetting if you run unleaded fuel. It will always look lighter than you'd think it should without the lead.
  • True. The pilot jet would be wrong, or some condition such as high float level or an air leak would be influencing the idle mixture.
  • The pilot jet and main jet can, as well as the starter jet (which nearly never needs changing). http://www.thumperta...ad.php?t=556427


  • 642MX

Posted June 23, 2009 - 08:36 AM

#7

grayracer thanks for the info and links. By the look of my plug the bike seems to be running good. I will mess with the idle mixture today and see what happens. From what I read if the idle mixture need to be less than 1 turn out or more than 2.5 turns out I need to re jet my bike? Can all the jets be reaches from bottom of the bowl?


If the "sweet spot" on the fuel screw is less than a turn out, you need a smaller pilot jet. If its more than 3 turns out, you need a larger pilot jet. And yes, you can swap the pilot jet by removing the 17mm nut on the bottom of the carb.

Welcome to TT. :worthy:

  • renodirtandsnow

Posted June 23, 2009 - 09:14 PM

#8

Thanks for all the replies and the welcome 642MX. I put the bike back together today. It seems the idles was best at 2 turns out on the air screw. From 2 turns out to 3 turns out it was about the same. Less than 2 turns and it idled worse. But one time while my bike was idling and it flat out stopped. Maybe the bike got a little hot while idling. I did puke a little coolant when sitting on the stand before I put the fan in front of the radiator. After I put the fan it front the bike and started it back up and it idled fine after that. I drove it up and down the street and it was not dying when I would slow down, stop suddenly or corner very slowly with no clutch. But I will have to get it out on the dirt to see how it really will act.

Only issue was very slight surge at steady throttle. But no popping or other noises.

I was told by a friend to run a main 165, pilot 45 and stock need in middle position for my altitude. What are the stock jets?. My manual is not very imformative about how to get to the jets. Can I access all the jets from the bottom of the carb? Any good links on how to safely remove the carb? I have the carb loose last night but could not figure out how to remove the throttle cables or other wires/cable coming into the top of the carb......

I will do a search right now but if you have a good link on carb re jetting please post it....... Thanks....

Dave

  • grayracer513

Posted June 24, 2009 - 06:10 AM

#9

I was told by a friend to run a main 165, pilot 45 and stock need in middle position for my altitude. What are the stock jets?. My manual is not very imformative about how to get to the jets. Can I access all the jets from the bottom of the carb? Any good links on how to safely remove the carb? I have the carb loose last night but could not figure out how to remove the throttle cables or other wires/cable coming into the top of the carb......

I will do a search right now but if you have a good link on carb re jetting please post it....... Thanks....

Dave

Remember I told you about this Sticky?

http://www.thumperta...ad.php?t=447989

Therein you will find a jetting how to, and info about removing/replacing the pilot jet with the carb in place. Look under Fuel Systems.

Also see the Jetting DB at the top of the index. Find my post within the '06 jetting thread for the stock jetting (your manual also lists them in section 2)

To access the needle, remove the upper motor mounts.

To remove the carb, remove the sub frame. To reinstall the sub frame, remove the air box from the sub, and clamp it to the carb, then slide the sub over it. If you want to see why you would do it this way, try putting the whole thing on at once first. :worthy:

  • renodirtandsnow

Posted June 24, 2009 - 08:13 AM

#10

Thanks gray.

  • renodirtandsnow

Posted June 24, 2009 - 02:55 PM

#11

Thanks guys for the links and help. Took longer to drive to the shop and pick up my new jet than the actual jetting process... Bike is very crisp off idle now with the new jetting of 165 main and 45 pilot. When I opened up the bike it had a 168 main and the 45 pilot. C clip is in the middle spot... I won't know the true effects until I hit the dirt. Installed the adjustable air screw as well. Just when I thought my 06 450F couldn't get any better....!!!!

Dave





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