Starting trouble after engine is flooded


6 replies to this topic
  • crush6742

Posted September 13, 2009 - 02:16 PM

#1

I was climbing a hill today and my '08 450F bike flipped backwards. I figured it would be difficult to start since it spent some time laying down, before I could muscle it back up and and back it down the hill. I figured the engine was flooded pretty baddly. I kick the bike 20 to 30 times and it would not start. Usually one or two kicks to start, never a problem. Since I was extremely exhausted from lugging the bike down the hill, and the crash itself, I tought I would try and give it some gas on one of my kicks; fired right up. Does this make sense when the engine is flooded?

  • grayracer513

Posted September 13, 2009 - 03:36 PM

#2

Yes, it does, because opening the throttle beyond about 1/4-1/3 will essentially eliminate any vacuum over the pilot jet discharge port, and the engine will have only the fuel already in the combustion chamber to work with.

In effect, this is what the hot start accomplishes also, but to a lesser degree; more air is allowed to enter the intake by bypassing the fuel circuits, reducing the vacuum signal to the pilot, and leaning out the idle. Cracking the throttle farther drops the vacuum to the pilot circuit below the point where it will deliver any fuel at all, and helps clear the flood. The trick is to open it far enough to clear the flood, but keep it closed enough to get it to run as it fires off of the accumulated fuel. Around 1/4 seems to work best.

Be advised: there is some risk of the bike kicking back if the throttle is opened while it's being kicked with the trans in gear, and it can kick back HARD.

  • milk

Posted September 13, 2009 - 03:52 PM

#3

would this be the same on a 426? man did i have a hell of a time today at the race... got my a$$ handed to my by the beast. didn't even make a full lap i was so wore out from stalling out(clutch cable stretched to the max and would pull even with the clutch lever fully pulled in so in the sloppy tight stuff when i'd try to slow down it'd stall and this was OFTEN lol) and kicking the thing over... i hate dnf'ing, i'd rather be dead last, but this bike killed me today(just got it last sunday btw)

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  • crush6742

Posted September 13, 2009 - 03:58 PM

#4

Thanks Gray. This is good to know. I always make sure to put the bike in neutral before starting as well.

  • grayracer513

Posted September 13, 2009 - 04:08 PM

#5

would this be the same on a 426?

Yes. As you are new to the bike, go to the Common Threads sticky and watch the two videos linked at the bottom of the page on the starting procedure, and then the thread on confirming the pilot jet setting. By far most real problems with starting a 426 have to do with jetting the idle circuit.

  • tribalbc

Posted September 13, 2009 - 04:17 PM

#6

My flooded 4 stroke technique has always been 5 kicks full throttle to clear it out, then one or two kicks no throttle and she usually fires right up. If not repeat.

  • milk

Posted September 13, 2009 - 07:52 PM

#7

Yes. As you are new to the bike, go to the Common Threads sticky and watch the two videos linked at the bottom of the page on the starting procedure, and then the thread on confirming the pilot jet setting. By far most real problems with starting a 426 have to do with jetting the idle circuit.


that's something i was kind of thinking about today as i was sitting out in the woods kicking my guts out lol. it seemed like the bike just wanted to die right off the bat so when i got it running a couple times i started playing with the air/fuel mix and it kinda helped out a bit but i had to turn it out a good bit to even get a decent idle so i was thinking maybe my pilot is too small. i will definitely check out that that thread though, thank you very much :busted:





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