2000 YZ 426 F It won't start????


15 replies to this topic
  • dgrizzz

Posted April 10, 2006 - 10:08 PM

#1

:thumbsup: Hello,
I have a 2000 YZF 426. My son rides this bike and rides well. He has had this bike for a couple of years. We recently went through the engine. It has been running very well. Last week he rode it on the weekend,Ran great. Started it this weekend warmed it up then shut it off by pulling the compression release as he has done many times before. Checked the oil. It was a little low, added oil then it wouldn't start again. Noticing also that it lost the hard spot in the kicker. Does this mean I lost valve adjustment that fast? Or do I have a intake problem with the carb?
So this is what I have checked so far.
I replaced and checked fire at plug=Good
I Pulled valve cover and checked cam timing=Good
I checked compression release return on shim hat=Good
I checked fuel flow to carb=Good
I Pulled air filter and it is clean=Good
I pulled plug and tried to hold rubber sealed compression gage to hole but it is to deep for my Gage. I don't have the right thread for my snap on Gage. However it does seem to have compression. But no stop at TDC with the kicker. So I ask does anyone have the magic answer? Its just funny that the kicker lost TDC stop.

  • viking_in_wa

Posted April 10, 2006 - 10:13 PM

#2

I also have a 426 and have read that using the dcomp lever as a kill switch is a huge no no. as i have read you may have some valve problems as a direct result of using de-comp lever to turn off.

  • dgrizzz

Posted April 10, 2006 - 10:32 PM

#3

Yea I heard the same thing. He broke the kill switch. we just havent been able to get it repaired yet. But still it wont even fire. No backfire or anything.

  • viking_in_wa

Posted April 10, 2006 - 10:42 PM

#4

could be some valve problems, grey racer will have some good advice for you when he gets ahold of this thread.

  • jbrooks26

Posted April 11, 2006 - 02:36 AM

#5

Sounds like you may have bent a valve. You can make yoru own leak down tester out of an old spark plug, a flex grease gun hose, a few brass fittings, and a quick disconnect for your shop air. This will give you the most information for the least cost. Otherwise you can take it to a good shop and have them do it for you. Hope this helps.

Josh

  • 00YZ426FMRCD

Posted April 11, 2006 - 08:29 AM

#6

Last week he rode it on the weekend,Ran great. Started it this weekend warmed it up then shut it off by pulling the compression release as he has done many times before.


That is not recommended and can't be good....

  • DrThumper

Posted April 11, 2006 - 12:13 PM

#7

You WHAT? Killed it by pulling the decomp??? I always heard that was bad, knowing a little about motor design I always figured it would be bad.

A buddy of mine said if he stalls it, he pulls the lever to aid in re-starting while he's still rolling. He did this going down the trail to show me...and....BANG....big noise from the head. Killed it alright, killed it to the tune of $500!

  • jbrooks26

Posted April 11, 2006 - 02:00 PM

#8

Ok guys, leave this poor man alone. He obviously didn't know any better, and I would be that this won't be happening any longer. He his here for help, and I haven't seen much of that offered. Let's show him what TT is all about here. I still say the leak down test will provide the most information at this point.

Josh

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  • ONLY4STROKES

Posted April 11, 2006 - 02:03 PM

#9

Noticing also that it lost the hard spot in the kicker. Does this mean I lost valve adjustment that fast?


More than likely it's the engine's compression, not the valves.

Do a compression check, and check the condition of the piston rings.

  • JESTERCYCLE

Posted April 16, 2006 - 01:38 PM

#10

Is it possible maybe the timing jumped or something along those lines using the decomp to shut it down? Just thinking out loud. My experience when a vehicle runs then no runs again usually timing related. :thumbsup:

  • 2fastwhitey

Posted April 16, 2006 - 05:19 PM

#11

Don't think it is timing related like some said, but I do think you possibly bent a valve. It sounds like your pretty mechanical so I would recommend for you to pull the head. Start by getting a good manual if you don't have one already, http://www.yamahaown...om.au/index.php here is the link to check it out online or download. I would start there you could always preform a leak test first but if the valve is bent it might still close to the seat. Try and see.

  • dr250andrew

Posted April 22, 2006 - 03:15 PM

#12

When i had my ttr125 the same thing happened but it wasnt the decompresion because it didnt have one. It wouldnt kick over at all and i figured the timing chain jumped track and it wouldnt allow it to kick at all. All i had to do was put it back on the track and retime it and it was fine. Try this because i think this might be your problem. And if you get it there you mine as well replace the timing chain because there farely cheap and its good insurance. If it breaks you will mess up alot of things. I hoped this helped and good luck with it.

  • Numskull

Posted April 23, 2006 - 06:58 AM

#13

My 426 recently lost the hard spot on the kicker cause I got dirt in the valves. The valves didn't seat causing compression loss.

Basically you have lost compression for what ever reason, and that is why the bike wont run. You just need to figure out why, which will probably consist of you pulling the head off for a visual inspection and a leak test. A leak test consist of using kerosene or solvent and filling up your intake port and then your exhaust port to see if the fluid leaks past the valves.

I have read on hear that the carburetor slide is subject to breaking from metal fatigue and will get lodged in the valve.

  • kid on a 426

Posted April 23, 2006 - 05:04 PM

#14

From what the description says I would put my money on a bent valve

  • bdruff

Posted May 29, 2009 - 09:47 AM

#15

My 426 recently lost the hard spot on the kicker cause I got dirt in the valves. The valves didn't seat causing compression loss.

.


I have another thread on here but the hard spon on the kicker seems to be there untill I start kicking it. I dropped a few drops of oil down the spark plug hole and it came back. When I start kicking it over, it wont start and the compression goes away. I ride at pismo beach in the sand dunes. Could sand have gotten in there somewhow and be doing the same thing. Ive ridden it since then at other places and it was fine.

  • chikn munky

Posted May 31, 2009 - 05:05 AM

#16

could it be possible that the cable that works the decomp may have stuck?





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