1999 Yz400 Will Not Start
Posted December 28, 2004 - 05:56 AM
I have changed the spark plug
Change the Air Filter.
It has a Handle bar Hot Start on it.
I have no Idea why it will not start. I bought a factory spark plug I asked if it was pregapped and the parts guy said "yes". Is that right?
Does any one have any other suggestions?
I have read some of the forums and notice something about Jetting. Would I need to rejett after a plug change?
From some internet research it seems these older 90 model yamahas are known for hard starts.
Any help or suggestions would be great.
Posted December 28, 2004 - 07:01 AM
1. With gas turned on, and cold start pulled out(black knob). Kick, with decomp lever in, about 3 times.
2. Let decomp lever out. Kick until it stops because of compression(it may take more take once)
3. Take kick start all the way to top. Pull in decomp lever and very slowly push kick starter so the piston is at top-dead-center( about 1 to 2 inches of movement of the end of the kick starter)
4. Bring kick starter to the very top and mak sure it grabs the last click.
5. Let go of decomp lever, and hand off throttle, KICK LIKE HELL!
6. If it doesn't fire up repeat 2-5.
That has worked for me every time. You just got to feel and imagine the position of the piston inside. I usually just do 2-5. If this does not work do a search on starting the 400.
Posted December 28, 2004 - 07:09 AM
Valves out of adjustment will cause hard starting.
It may need to be re-ringed if it never has before.
If the timing chain has never been replaced it could of jumped timing. There was a rash of timing chain failers last year on the 99's. Seems they reached the end of there life at around the 4 year mark. Bad tensioner could also cause jumed timing.
Completely disasemble the carb and thourgly clean it.
Check all the electrical conections and make sure that they are clean and dry. Squirt some di-electric grease into them.
Ok a few dumb questions. When you slowly kick it thru the stroke, when the piston hits TDC the kick starter stops form the compression. You then need the compression release to bump it past. If you can kick it past TDC without the compression release you may have valve isues or need re-ringing.
What I always do it eleminate the possible causes and whatever is left has got to be the problem. You need gas spark and compression. In order to get compression you need good rings, valves sealing and shimmed properly, Cams timed corect.
Good luck. The more detailed info on what you have checked the more we can help.
Posted December 28, 2004 - 08:15 AM
My '99 YZ400 just had a similiar thing happen to it. It seemed to be running fine and then out of nowhere it just stopped running. It wouldn't start for anything. My friend diagnosed it as being related to the compression rings. He did this by the method that yzman400 stated which is the ability to kick the bike past TDC without using the decompression lever. For me anyway, it wasn't just the fact that you could kick it past TDC, but more the fact that you could do it easily.
I just got the bike back yesterday. I can't wait to take it out to see how much better it runs now!
Posted December 28, 2004 - 08:36 AM
Posted December 28, 2004 - 09:32 AM
And No I can not kick it without using the compression lever. I am going to try these and let you know how it goes.
Posted December 28, 2004 - 10:06 AM
Posted December 28, 2004 - 12:46 PM
Sounds like you have compression. Turn on the gas and tip the bike over on its side and look for gas spewing out of the vent tubes. That will tell ya if gas is getting into the carb.
Hey what is your temp around there right now? These bikes can be a bear to start in cold temps around say 30 deg and below. Rejeting is usually needed to get them running in the cold winter months.
Have you checked for spark? Take the plug out, plug it into the plug wire and rest the plug against something metal and kick to check for spark.
Posted December 29, 2004 - 04:19 PM
Its been in the 20's and thirtys'with a windchill in the 10's
so it could be a jetting issue if you say it usually needs rejetting in colder temps.
Any good sites on talking about "How to rejett your bike"
Thanks for the tips
Posted December 29, 2004 - 04:53 PM
Another suggestion I did not see is the Kill Switch, Take the kill switch off, this may be defective and causing no spark, Make sure you are getting spark as well.
As far as starting goes, follow the drill, live it love it sleep with it and never never ever let anyone twist tat throttle when the bike is not running
Welcome to TT
Posted December 29, 2004 - 04:55 PM
So I tried starting it again and nogo.
I tried turning it on its side and gas came out of the vents.
I do get a loud single pop once or twice. What does this mean?
Still not sure if I got the idle scree correct.
Posted December 29, 2004 - 05:30 PM
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