'06 450 won't start after I lay it down


14 replies to this topic
  • goosey

Posted September 16, 2013 - 08:02 PM

#1

So I'm going to list a few ill symptoms of my bike and hopefully someone will say, oh that's easy lol

 

starts easy with choke when cold.

 

If off for 30 mins or more I need the choke again, that can't be right, tells me I need a bigger pilot right?

 

pops on decel, but not nearly as bad since I increased the main jet size

 

when the bike gets layed down, from crashing, it won't start. It usually starts right up when it's hot w/ the decomp lever but I can never get it started after its layed down, even trying to pop it in second.

 

Just now realizing I haven't put in a thumb turn air screw, but it can't be that easy could it? Could float level cause that? no right cause the needle valve should be doing its job. 

 

I need to fix this cause I couldn't finish the last two races, super frustrating.

 

any input is appreciated, thanks.



  • grayracer513

Posted September 17, 2013 - 06:41 AM

#2

The float needle may be faulty on another score, but it's not capable of controlling the float level while the bike is on its side. Pick it up or turn the gas off ASAP.  In this condition (flooded), the best thing is to open the throttle 3/4 or more and hold it that way while turning the engine slowly through 2-3 compression strokes.  With the throttle that far open, there will be no intake vacuum, so no more gas will enter, only air, and that will help dry things out some.  Then try to start it with the hot start, then without, then by cracking the throttle open only very slightly off idle.

 

The main jet has nothing to do with decel popping:

http://www.thumperta...t/#entry2983539

 

Your pilot screw may simply need an adjustment, but it may be the wrong size, too.

 

http://www.thumperfa.../jetting.htm#PJ

http://www.thumperta...ircuit-setting/



  • vic2340

Posted September 17, 2013 - 07:58 PM

#3

Ok you jet the bike properly,(that means no decel popping, no bog what so ever when warm, and no hesitation anywhere in the rpm range) then when you lay it down you hold in the hot start lever and clear it with three kicks or so, then get the kick lever to a stiff kick position then keep the hot start lever in and kick it good. it should start no problem. Oh and if you kick a four stroke with the throttle open get ready to get donkey kicked because it will back fire. Also on my bike if i ever touch the throttle it wont start or will take an extra kick or so from the time I touched the throttle. I have a 2009 yz450f and have had two 2008 yz450's 



  • grayracer513

Posted September 18, 2013 - 06:36 AM

#4

... no decel popping, no bog what so ever when warm, and no hesitation anywhere in the rpm range

 

That's not proper jetting.  You would necessarily be too rich to accomplish what you describe.

 

 

 

if you kick a four stroke with the throttle open get ready to get donkey kicked because it will back fire.

 

 

It might, but it probably won't.  Notice I said "turn the engine slowly" in any case. This is to clear the flood, not start the bike.

 

 

on my bike if i ever touch the throttle it wont start or will take an extra kick or so from the time I touched the throttle.

 

More evidence that you're too rich.



  • vic2340

Posted September 18, 2013 - 06:49 AM

#5

Can you please explain how my bike is running poorly because of bad jetting because i dont think you e ever heard it even run. I own a 2009 yz450f with a stock exhasust and stock jetting. When my bike is warm i can nail the throttle off idle and it wont even stumble. I can go 5 mph in 5th gear and do a wide open throttle roll on with no hesitation. There is no backfiring or decel popping and my bike has never over heated. How can this be improper jetting. Also my bike takes at most 2 kicks to start unless i dump it. (You can look up at my post and see how i start it if that happens) And my bike has never not started on a dead start hole-shot.

  • vic2340

Posted September 18, 2013 - 06:55 AM

#6

And by saying by touching my throttle it wont start i miss led you. I ment to say it makes it harder to start and may take an extra kick to start if i do so. Anyways i just want to hear your explanation maybe you can teach me somthing

  • grayracer513

Posted September 18, 2013 - 09:03 AM

#7

If it never pops on decel, it's too rich on the pilot.

 

If you can snap the throttle from idle to WOT without a stumble, your accelerator pump shot is too big. 

 

The first problem can and usually does lead to stalling on a quick throttle chop from a low RPM, moderate to large load because it causes the engine to drop under the actual idle speed on a sudden release as that. 

 

The second condition will lead to loading up as you work through a turn or other section where you have to move the throttle around a a lot to find or maintain traction. 

 

Mine never bogs, but it's not because I can't make it do that by snapping the throttle open; it's because I learned to roll the throttle on a long time ago. You wouldn't know to hear the engine that I had not flipped it open that quickly, because the response is near instant, and I don't have to think about it at all. 



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  • vic2340

Posted September 18, 2013 - 06:55 PM

#8

You see that makes some logical sense I understand. Now do you think that my bike behaving the way it does im missing out on something? In other words do you think that I could gain some horsepower or something by making my bike a little leaner? and you may have mentioned it but what is the major downfall to my bike being a bit rich? (im not trying to sound like a smart ass im just trying to learn) 



  • goosey

Posted September 18, 2013 - 07:16 PM

#9

there is no downfall,  you're bike is jetted fine. if you were looking for that extra three thousandths of a second on the track to beat the guy to the next turn - you'd might change it. There's a little more potential for your motor to be the slightest bit crispier, some guys chase it for no good reason except skill and something to do while others chase it for position and points. Plus your engine will last a little longer jetted like yours. 



  • vic2340

Posted September 19, 2013 - 01:31 PM

#10

Ok I understand. Thanks for replying sorry for getting off topic a bit but I enjoyed the conversation. I hope you solve your engine starting problem. These four strokes can be quite Finicky

  • grayracer513

Posted September 19, 2013 - 03:41 PM

#11

You see that makes some logical sense I understand. Now do you think that my bike behaving the way it does im missing out on something? In other words do you think that I could gain some horsepower or something by making my bike a little leaner? and you may have mentioned it but what is the major downfall to my bike being a bit rich? (im not trying to sound like a smart ass im just trying to learn) 

 

Your top end may last a little longer, but a lot depends on your riding style and the kind of riding you do.  Someone riding short track events, or a lot of off-road stuff would probably notice the loading up at low RPM from the excessive pump activity.  An off-roader would very likely notice the stall issue.  Picture the situation this way: the trail suddenly turns up a sharp short climb, so you accelerate up to where you suddenly find a turn at the top that requires you to drop the throttle.  You charged the climb pretty hard at about 4500 RPM just to get up cleanly, but then when you chop the throttle, it died, even though you pulled the clutch.  Pilot too rich.



  • vic2340

Posted September 19, 2013 - 06:39 PM

#12

I see what your saying, I can recall my bike being much more prone to stalling than my yz250 even though I added a 9.2 oz weighted flywheel. I ride offroad trails most always. Can i just adjust my fuel screw or will that not be sufficient enough, its at 2 & 1/4 turns out, stock being 1.5 turns



  • grayracer513

Posted September 20, 2013 - 06:27 AM

#13

I see what your saying, I can recall my bike being much more prone to stalling than my yz250 even though I added a 9.2 oz weighted flywheel. I ride offroad trails most always. Can i just adjust my fuel screw or will that not be sufficient enough, its at 2 & 1/4 turns out, stock being 1.5 turns

 

The big 4-stroke is always going to be easier to stall than the 2-stroke half its size unless you hang a lot more weight on it than you can with the tiny flywheel yours came with.  Their compression at low speeds is far greater than the pinger, and they have 3 non-power strokes to roll through instead of one.

 

The "1.5" figure is actually "1.0-1.5", and it's really just a guideline.  Read:

 

http://www.thumperta...ircuit-setting/

 

The thing is that the '09 did tend to be a bit lean on the transition from idle to main circuit as the throttle is opened, and what works quite well to fix that is to change to an NFPP needle ( clip in the 3rd groove ).  This needle has a smaller diameter on the upper straight section that affects jetting between just off idle to about 1/4.  Moving the clip won't change that because that only moves the tapered section higher or lower, and the taper doesn't start to clear the nozzle until around 1/4.

 

If you ride mostly MX, I'd drop the leak jet from 55 to 50.  For off-road, I might not do that. 

 

Here's where I'd go with it:

 

Pilot: 43 (45 is stock) this will let you run the screw out at closer to 2 turns to get a little better air/fuel mixing in the circuit

Main: 165

Needle: NFPP (3) (PN 5TA-14916-PP)

Leak jet: 50



  • vic2340

Posted September 20, 2013 - 08:26 PM

#14

This jetting recommendation is easy for me to do, I have all the parts except for the needle, I have a close friend who is bound to have it. I will definitely try it out. I have nothing better to do since my leg is still recovering from surgery. (dirt bikes do this to you). You've been a great help thank you for everything, if I need anything else I will know who to ask.  



  • goosey

Posted September 22, 2013 - 06:46 PM

#15

ok so I got a chance to look at the bike finally, other bikes n racing got in the way  :ride:  :rolleyes:  :thumbsup:

 

what if I told you my catch can was so maxed out with fuel (it's built into the frame under the motor) that it overflowed out of the vent tube that was routed to the airbox lol. So I said hmph, if I drain it, maybe it'll start right up. Nope. So then I held it open 3/4 and bam it finally started.

 

Maybe I should of held it open at 3/4 immediately after I fell too?

 

Hopefully this is where this thread gets interesting since this may not be a jetting issue  :thinking:







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