99 yz400f won't start

8 replies to this topic
  • BikeLifeHouston

Posted September 28, 2016 - 02:32 PM


Yes I just traded my 2005 Kawasaki 250 klr for a 99 yz400f the bike doesn't run & they guy I traded informed me that the carb needs work & a fuel screw I've been tryna kick the bike but I'm getting no reaction could someone please help me? There is no fuel screw in right now

  • bobsled

Posted September 28, 2016 - 03:29 PM


Afaik, You will never get it started without the fuel screw.

What you need is:

1) beer, plenty

2) a buddy to help ya out, that knows carbs

3) a parts breakdown for your carb, so you can order parts

#2 is optional, since you have TT! 

tear down the carb, identify everything that is missing/needs replacement, & then rebuild your carb

I'm scared the PO may have scammed you into buying/trading for a bike that needs more than just carb work....be prepared to do top end work at bare minimum

Keep us posted!

  • Slow and Jerky

Posted September 29, 2016 - 04:00 AM


At the very least you need the fuel screw, spring, washer and o-ring. Off the top of my head I think the adjustment is about 2-1/2 turns out, but get a manual. You can download one for free here: https://www.yamaha-m...uals/index.aspx


You might as well pull the carb and clean the jets while you are at it. Keep in mind to avoid actual carb cleaner on any rubber parts. I generally only use brake cleaner and compressed air. You should be able to see day light through the jets. If the pilot jet is really plugged use a small sewing needle and brake cleaner until you get it cleared out, but be careful you don't hog out the hole; or just replace the jet.


I would also put a new spark plug in it, for whatever reason once they flood it's way easier to change the plug than to kick it long enough to dry the plug out, assuming it's any good in the first place.


The carbs on these are not really too bad to work on, but take your time, have a clean area to work and take lots and lots of pictures as you disassemble. I would guess there are plenty of Youtube "how-to" videos for cleaning this particular style of carburetor.


Also, while you have it torn apart it would be a good idea to check the valve clearances, if they are too tight it makes it very hard to start.


Don't stress too much, these are very solid engines. Once you get it dialed in and learn the magic joo joo starting sequence you should be happy.

  • grayracer513

Posted September 29, 2016 - 01:02 PM


Real carb cleaner won't harm parts in a carb any more than gasoline does.


If there is no fuel screw at all, you're basically wasting time trying to get it running. 


The first thing that happens when one of these sits too long is the pilot jet clogs.

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  • BikeLifeHouston

Posted September 29, 2016 - 03:00 PM


So basically the carb just needs to be cleaned out my fuel screw is posed to be here Saturday I've been YouTube since I got the bike I thought I was just doing the kicking process wrong but the bike is in good condition

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  • lordhelemt

Posted October 01, 2016 - 05:59 AM


I bought a non-running '98 yz400f earlier this year. Once I got the carb off it was filthy. Decided to spend the money on one of those HF ultrasonic cleaner (~$50 with coupon). Dissembled the carb and ran a few cycles in 50/50 water/simply green with the heat on. Blew all the passages and jets with compressed air and reassemble. Started 1st kick

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  • BikeLifeHouston

Posted October 01, 2016 - 08:13 AM


What's wrong water/simply green I'm scared to disassemble the carb myself I've watching videos but I don't wanna mess anything up I know cleaning the carb yourself is easy lol

  • BikeLifeHouston

Posted October 01, 2016 - 08:15 AM


Wym you ran a few cycles in 50/50 water / simply green idk what that is lol

  • BikeLifeHouston

Posted October 01, 2016 - 08:21 AM


What specific tools do I need to disassemble carb & clean do y'all know?

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