starting problem again


7 replies to this topic
  • honda0071

Posted January 15, 2008 - 02:56 PM

#1

i am trying to start my 1998 yz400f and for some reason it isn't working.... i can start the bike easily since know the starting sequence. always it will start first kick but then die out not long after it is started... i have messed with the fuel screw turning idle up and down and really i was working good for a little while idling good with choke on... then when i think its warm (which is usually 3 mins... is that long enough?) i go to turn choke off and the bike just shuts off... then i start it again and the same thing happens... then after about 10 different times of me starting it it seems warm but does not like to idle with no choke... only 1 time i've got it to idle with choke off so then i tried to take off in first gear and it died. so please ne help greatly appreciated...

  • Birdy426

Posted January 15, 2008 - 06:16 PM

#2

Did you clean thecarb as previously suggested?

  • honda0071

Posted January 15, 2008 - 09:32 PM

#3

no i have not... but heres more info it pops on deceleration... and it it likes to start with like 1/16th of throttle opened when warm? it doesnt like to start with the hot start either even when warm... so not sure.... im prob gunna clean it and see what happens then if nothing is beter i will send it to Zip Ty racing and have them do the racing carb upgrade and see if it helps... do u think it will help?

  • Birdy426

Posted January 15, 2008 - 09:48 PM

#4

I would get the idling problem sorted out before I sent the carb off for mods. One thing at a time. Pops on decel is typically lean condition (too small or plugged up pilot jet or fuel screw set too lean) or a leak where the header clamps to the mid-pipe.

You really need to start with a carb that you know is good, then experiment with idle settings, fuel screw settings, and jetting until you get a good idle, roll on throttle response, etc. How does the motor respond when you roll on the throttle? How about when you whack it (the throttle, I mean...)? That may give you a clue on where to look as well...

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  • USED YZ426F

Posted January 16, 2008 - 09:09 AM

#5

Clean your carb. You probably have a clogged pilot circuit. Once you get the carb cleaned, verify the jetting so that you know what is in there now.
Then drain the fuel tank and make sure that it is clean inside. Start with a fresh tank of premium gas and see how the bike behaves before you start sending things out for mods.

The popping on decel is normal. Yes, it indicates a lean condition, but unless it is very severe it is nothing to lose sleep over (my 426 pops on hard decel going in to turns).

  • William1

Posted January 16, 2008 - 09:17 AM

#6

Not to differ with everyone, but clean the carb. Maybe even get wild and replace the pilot jet.

  • honda0071

Posted January 16, 2008 - 06:44 PM

#7

thank you i will clean the carb tomorrow and check all the jets... so think its prob the jetting mayb just a dirty carb not anything bad.. i rode it today for the first time on the trails, wich was hard since i basically couldn't let it idle i had to stay on clutch or on gas the whole time. but other than the popping, it even pops under small blurps of throttle... but not so much when i go full throttle and let it go to slow down. only when i whack the throttle so much than full throttle it pops.

  • grayracer513

Posted January 16, 2008 - 07:44 PM

#8

Another thing you need to learn is to roll the throttle open smoothly, not snap it like some kid on a two stroke. In time, you'll learn to open it a little more slowly, let the engine catch up, and open it faster as the engine speed picks up. Once you get it down, you'll do it without thinking, and the engine response will look and sound instantaneous to everyone else.





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