07 450 will not start when cold


9 replies to this topic
  • gtxkid

Posted April 19, 2007 - 09:57 AM

#1

What are some things that cause it not to start.
Has 10 motos on it and little off track time.
Used to be i could give it 3 to 4 pumps of the throtle and would fire right up.
Thinking about valve adjustment.
Already changed plug.

  • never59

Posted April 19, 2007 - 11:30 AM

#2

What are some things that cause it not to start.
Has 10 motos on it and little off track time.
Used to be i could give it 3 to 4 pumps of the throtle and would fire right up.
Thinking about valve adjustment.
Already changed plug.


how do you have your bike jetted?

  • WB450

Posted April 19, 2007 - 11:57 AM

#3

What are some things that cause it not to start.
Has 10 motos on it and little off track time.
Used to be i could give it 3 to 4 pumps of the throtle and would fire right up.
Thinking about valve adjustment.
Already changed plug.



May want to check the valves.

  • sprint4425

Posted April 19, 2007 - 01:21 PM

#4

welcome to the revolution of the four stroke mx bike.

When you say that it wont start when its cold, do you mean that the engine hasnt been run in a few days and the weather temperature is about 60-65 or above? Or do you mean that the engine hasnt been started in awhile and its almost cold enough outside to have snow on the ground?

THe reason why i ask is because four stroke MX bikes have a VERY hard time starting when the temperature outside is cold (therefore turning the engine block cold). To remedy this, put the bike in the garage and set some sort of decent sized heater next to it facing the engine. Make sure not to get too close so you dont burn plastic, gas lines, etc. Warming up the engine block should help a lot as far as starting the bike.

If the weather where you are at is at (my best estimate here) 60-65 degrees or above I would recommend the usual engine-staring tune-up stuff before i got into anything major. Replace the plug, make sure the air filter is clean, four strokes dont take well at all to throttle adjustments while starting the bike (what i mean is, dont turn the throttle at all when starting the bike. It might even be good practice to keep your hand completely off the throttle while starting). Also, use choke nominally. It might take a little while, especially if its the first start of the year. But it should crank up eventually.

If none of this works, then i would start looking into valve and possibly carb adjustments. I wouldnt worry too much about that though because it doesnt sound like you have ridden the bike enough to where that should be a problem yet.

  • rexbond007

Posted April 19, 2007 - 05:20 PM

#5

I'm thinking it could need a larger pilot jet and bump up the idle screw and or air screw needs to be turned out a little.....

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  • gtxkid

Posted April 19, 2007 - 06:42 PM

#6

I changed the plug (no differance).
The Cold weather in Colorado is most of the problem.
Try to start in the morning with no luck.
I did change to an aftermarket adjustable air screw.

One time i had to take the choke off for it to start and anouther time i had to hold the throtle wide open.
It seam fine before, not sure what is going on.
The dealer in Denver Jeted it for me so i have no idea what they used.
Started good and Ran realy well with no boging at all.
They told me they sent a carb. to CALF. and then copy all the mods to use for the bikes they sell.
Going t check it out at the track for practice SAT.

  • Polar_Bus

Posted April 20, 2007 - 02:52 AM

#7

What are some things that cause it not to start.
Has 10 motos on it and little off track time.
Used to be i could give it 3 to 4 pumps of the throtle and would fire right up.
Thinking about valve adjustment.
Already changed plug.


A simple trick to try is to back out your fuel screw 1/2 turn. This richens up the closed, to 1/4 throttle circut. It helped my bike start, and run better in the cold. Don't be afraid to run a higher idle. I have learned over the years with the race 4 strokes, a higher idle makes for easier starting also.

  • grayracer513

Posted April 20, 2007 - 08:04 AM

#8

Don't be afraid to run a higher idle. I have learned over the years with the race 4 strokes, a higher idle makes for easier starting also.

My '03 will not start when cold unless I crack the throttle just slightly. Somewhat the same thing.

  • gtxkid

Posted April 23, 2007 - 05:14 PM

#9

Seams i have to pump it 4 times and then hold the throtle open a little.
Thans guys for helping me get it right.:applause:

  • rexbond007

Posted April 23, 2007 - 07:27 PM

#10

Seams i have to pump it 4 times and then hold the throtle open a little.
Thans guys for helping me get it right.:applause:


If your doing that, then you need to go up on the pilot 1 size





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