1999 Yz400f starting


19 replies to this topic
  • mespey08

Posted September 21, 2011 - 02:38 PM

#1

I have a 1999 Yamaha Yz400F. It is very bad with cold starting now and seems like it never used to be like this. I just recently changed the fuel like and carburetor line as well. It has a full White Brothers exhaust as well. It starts fine right after it warms up, but like I said it seems like it takes for ever to start. I would say at least 10 kicks. Also, how long should it typically take before I can run it and it is warmed up? Because I notice after a minute or two of warming up it will die. But after 5 minutes I can give it throttle and it is fine. It also pops a ton when I rev it up and let of the throttle.

Any suggestions or help? Thank you very much ahead of time.

  • grayracer513

Posted September 21, 2011 - 03:39 PM

#2

If it has sat unused for a period of time, it's likely that the pilot jet is varnishe, and possibly the starter jet as well. Read:

http://www.thumperta...726#post8021726

  • 1991CR250RBEAST

Posted September 23, 2011 - 05:10 AM

#3

Are you doing the "starting procedure".When I got mine I knew nothing of it and it would take forever to start.Now it starts first or second kick every time when using the proper technique.

  • mespey08

Posted September 24, 2011 - 07:45 AM

#4

I believe I am.. Can you give me the procedure you do? I will try it and see if it works? After the bike is running for a bit. It starts right away.

When I got the bike the guy I got it from said this...
1. Dont give it gas at all.
2. Pull choke when it is cold. When it is hot don't
3. Pull in compression lever on left side over clutch.
4. Kick starter down 2 times slowly.
5. Release compression lever.
6. Kick it from top to bottom.

That's what he told me when I got it. Works great when it is hot. But if it is cold. I can almost kick my leg off. Seriously my leg gets tired by the time it starts. SUCKS. I loved my electric start, but it didn't have the power this BAD A** 400 does!

  • Schpenxel

Posted September 24, 2011 - 09:14 AM

#5

You need to slowly push the kick starter to the stiffest point of the stroke. Once it gets too hard to move any further, pull the decomp lever and move the kick starter another inch or so at most. Release decomp, let kick starter move back up to near the top of it's range and kick solid/smooth, not jerky

It does not sound like you're doing it right to me. the idea is to release some of the compression but still ultimately kick through the remainder of a compression stroke so t'll fire. If you're trying to push it through an entire compression stroke I'm surprised you haven't broken a leg yet lol

Edit: just re-read your technique. It's wrong. 1-4 are right, but after that you need to kick slow until you feel compression and it won't go any further without a lot of force, pull decomp, push another inch or so, release decomp, then kick all the way through. Sounds complicated but is easy once you do it a few times

  • falkz89

Posted September 25, 2011 - 03:25 AM

#6

For the most part, your technique seems okay. As Schpenxel said, pull in the decomp lever and drop it another inch, then release the decomp lever and bring the kick starter back to the top. Push back down until you feel the firm point and kick it over smoothly and forcefully. The rest of your technique is fine.

On another note make sure your spark plug is clean. I found that my 400 was an absolutely pig to start if the plug was a little dirty, but it would fire up like a gem with a new/clean plug. It took me about half a dozen plugs before I had my jetting set well enough to stop sooting/burning up plugs

  • The Spanky

Posted September 25, 2011 - 03:41 AM

#7

I believe I am.. Can you give me the procedure you do? I will try it and see if it works? After the bike is running for a bit. It starts right away.

When I got the bike the guy I got it from said this...
1. Dont give it gas at all.
2. Pull choke when it is cold. When it is hot don't
3. Pull in compression lever on left side over clutch.
4. Kick starter down 2 times slowly.
5. Release compression lever.
6. Kick it from top to bottom.

That's what he told me when I got it. Works great when it is hot. But if it is cold. I can almost kick my leg off. Seriously my leg gets tired by the time it starts. SUCKS. I loved my electric start, but it didn't have the power this BAD A** 400 does!


The previous owner was an idiot. I'm amazed you ever get it running starting it like that.

If the engine is cold:
1. Pull the choke knob out
2. slowly push the kicker until you reach the point of high compression (TDC).
3. Pull the compression release, and slowly move the engine just barely past TDC (it will only take a couple of inches of kicker movement).
4. Give the throttle two full twists to prime the engine with the accelerator pump
5. Take your hand off the throttle so you don't accidentally twist it while kicking
6. Start at the very top of the kicker stroke, and push the kicker all the way through to the bottom of the stroke.

It's NOT a two-stroke, don't kick it like one. You don't have to give it fast rabbit kicks, just push the kicker all the way through the stroke. If you kick it too fast it won't usually start.

If it doesn't start after two-three kicks, pull the hot-start and the compression release and kick it ten times to clear it out, and repeat the procedure.

  • mespey08

Posted September 25, 2011 - 01:49 PM

#8

Thank you everyone for your reply's. Yes, sounds like I was doing it way wrong.. Who is the bigger loser though the person who had it before me or myself for not knowing how to start my own bike. ouch.. Anyways I will try the new start procedure. I also took out the plug it looks terrible rust around the top and black as heck. Thanks for the information. As far as my jetting. I have a full white brothers exhaust. Does anyone know what my jetting should be like.. Also, my bike has a choke lever, but no hot start.

  • The Spanky

Posted September 25, 2011 - 02:57 PM

#9

my bike has a choke lever, but no hot start.

Yes it does. There are two knobs on the carb that pull out. One is the choke, the other is the hot-start.

  • grayracer513

Posted September 25, 2011 - 03:00 PM

#10

The hot start on the 400 was separate from the carb. It mounted on the frame near the air boot, and fed air into the intake port on the head via a hose. If it isn't there, be sure that the port it connects to is blocked off.

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  • The Spanky

Posted September 25, 2011 - 03:06 PM

#11

The hot start on the 400 was separate from the carb. It mounted on the frame near the air boot, and fed air into the intake port on the head via a hose. If it isn't there, be sure that the port it connects to is blocked off.


Hmmm...you know, all the times that I rode my buddy's '98, I never noticed that the hot-start didn't actually connect to the carb body. I just pulled the knob...:smashpc:

  • DeeCee

Posted September 25, 2011 - 07:16 PM

#12

There is a video in the sticky's at the top of this forum. Shows the starting technique for the 400 very clearly.

  • 1991CR250RBEAST

Posted September 25, 2011 - 09:36 PM

#13

I've never had to use my hot start on my '99. I removed it and capped the holes.

  • mespey08

Posted September 26, 2011 - 11:38 AM

#14

I actually do not have a hot start either. It is blocked off as well.

So I do have an update though.....
Yesterday I was sick of breaking my leg to start the thing so I took off my spark plug. Holy Crap is it hard to get to if you don't have the right tools and extensions for the socket. But anyway. I took it out and it was way way black and looks like there was still gas/oil on it, as well did it look like it has not been changed in ages since 99'. Not like the gas is burning right. So I got a new plug and went out to start the sucker and now it is not wanting to start.
Does anyone know what my settings on the carb should be?
Also how hard is it to take of the carb? I am going to clean that sucker too.

Thanks for all the help everyone!

  • falkz89

Posted September 26, 2011 - 06:42 PM

#15

Have you checked the new plug for spark? Just to be sure it isn't faulty. Usually you shouldn't have a problem starting it with a new plug if everything has gone back together properly. Particularly since it was starting before. Check for spark first and make sure you've got your coil plug seated firmly on the spark plug when it goes back in. The carby can be a bit tight to remove, but by the sounds of it a good clean wouldn't go astray. I found with mine after loosening off the clamps, have a second person pull the air boot back into itself to give you more room to remove it. I can't remember the carb settings off the top of my head, but someone here can surely help you with that

  • mespey08

Posted September 27, 2011 - 05:54 AM

#16

I took the Carb off last night my gosh was it terrible. I am glad I cleaned it being I am suppossed to go for a nice long ride this weekend. I believe after I get it put back together I will be good to go. My gaskets on the carb were all dryrotted also.. Also I never heard of this carb on here its a Kehin flat cr is what it says on it. Is this the stock carb?

  • grayracer513

Posted September 27, 2011 - 07:11 AM

#17

...I never heard of this carb on here its a Kehin flat cr is what it says on it. Is this the stock carb?

Probably, yes. There are numbers stamped along the left side above the float bowl. If it's the OEM carb and a '99, it should start with 5BE1 01.

DO NOT separate the upper section of the float chamber from the rest of the carb body. There is a formed "O-ring" seal in that joint that is not available anywhere. Of course, if that leaks, it can become a problem.

  • mespey08

Posted September 28, 2011 - 09:15 AM

#18

It is the stock carb. I finally stuck it out and bought the clymer manual.. 35 dollars later.. I did take that part of the carb off and my oring seal dealio is actually in great shape. Not the seal around the bottom part. Not good. I already bought a new one and have it all back together.. But I do have a question I can not find this out anywhere..
I have a 99yz400f with a white brothers exhaust e series. Model#2000. Full titanium header also. What should the jetting be? On the main it is 2 and 1/4 out. This seems alot. I think it should be in more, being the manual says 1 and 3/8 out. I live in ofallon Mo 63366 and never ride if it is over 70f. Too Hott.. Anyone know this?

Thanks again for the replys!

  • grayracer513

Posted September 28, 2011 - 02:40 PM

#19

I finally stuck it out and bought the clymer manual.. 35 dollars later..

For those who would like to avoid that expense, open the Common Threads Sticky, you know, the one at the top that says "look here first"? There are two links tho FREE downloadable manuals.

  • Ryan426

Posted September 28, 2011 - 06:16 PM

#20

wound'nt hurt to check the valves too imo. :smashpc:





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