2001 yz426 problem


30 replies to this topic
  • GONE1445

Posted September 03, 2006 - 05:48 PM

#1

OK I went to ride my bike today and I started it with the choke on as always when cold and it seemed to idle higher than normal then when I got it warm I shut it down and checked the oil it was perfect so I went to go ride and after I took it off choke it would idle for a minute then stall out I bump started it 3 times today because it stalled while I was flying down this Field

it also pops a lot more than usual when I let off the gas to coast or if I rev it when in neutral it pops a lot I know some popping is normal but it never did it this much before and I have touched nothing since buying it 2 years ago and it has ran like a champ till now

what would cause this?

I do have PMB end cap with the spark arrestor thought that might be clogged took it out and still does it??

could it be a dirty carb

oh yea and is that big black knob on the bottom of the carb the idle or the fuel screw??

  • grayracer513

Posted September 03, 2006 - 06:01 PM

#2

The big black knob that sticks out on the left side of the carb is the idle speed screw. The fuel screw goes straight up from the bottom of the float bowl.

So, this is a silly question, but, is your hot start knob pulled out?

  • GONE1445

Posted September 03, 2006 - 06:15 PM

#3

nope I thought that too but it is in as far as it will go

I am gonna try cleaning the carb tomorrow and see if that helps it probably needs it and I'll throw a new plug in there and clean my air filter

I thought I saw some where on here on how to take your carb off?? dont remember link maybe?

  • mike_dean

Posted September 03, 2006 - 06:16 PM

#4

Could be the hotstart is out, or you have a vacuum leak, both cause a high idle, possibly the rubber boot between the carb and head is loose or leaking. Mike

  • 02YZ426

Posted September 03, 2006 - 06:19 PM

#5

Try changing the spark plug, could be as simple as that. I've had the same trouble before with my 426 and the plug looked fine, but when I put a new one in, the problem was gone.

  • GONE1445

Posted September 03, 2006 - 09:20 PM

#6

will do the idle is only high when I have the choke in and it just seems higher than usual to me dont know I think I put 87 octane in it tho will that make it pop a lot

  • grayracer513

Posted September 03, 2006 - 09:30 PM

#7

No, low octane fuel will make it ping, not pop. It's lean at an idle. Back the fuel screw out 1/4 turn or find your air leak.

Could also have picked up some dirt in the fuel and partly blocked a jet.

  • GONE1445

Posted September 04, 2006 - 03:57 PM

#8

ok today I took the whole dad burn thing apart and completely cleaned the carb found a freyed thorttle cable( what kind should I get and are they sold in pairs or just one) and just went through the bike and cleaned cleaned cleaned so she should run like a champ when I am done

now I gotta order air filter (thinkin ready), throttle cables, chain and sprokets

  • GONE1445

Posted September 05, 2006 - 02:49 PM

#9

ok got another ? when I had the carb off I looked down the intake of the head to make sure nothing was in there and noticed some gunk on the outside valves but the middle was squeaky clean &%$#@! and if I switch to synthetic oil will it clean some of that gunk out?

I think I am gonna go with AMSOIL I currently run yamalube 4-stroke

what is the diff between that and the 4R stuff

  • grayracer513

Posted September 05, 2006 - 03:32 PM

#10

... noticed some gunk on the outside valves but the middle was squeaky clean &%$#@! and if I switch to synthetic oil will it clean some of that gunk out?

That's typical. Because the fuel droplets are heavier than the air they're suspended in, most of them tend to go straight down the center port instead of making the turn left or right at the split. Since it is the fuel additives that clean deposits off the valves, the center valve ends up much cleaner.

Although I do recommend Amsoil MCF and MCV, it won't reduce the carbon deposits on the valves. That's not the oil's job.

The difference in the two YamaLube 4-stroke oils is that one's a synthetic, and the other one isn't. I don't care for either of them.

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  • mankind810

Posted September 06, 2006 - 02:35 AM

#11

Sorry to go off topic but Grayracer why do you not care about the yamalube oils?

  • grayracer513

Posted September 06, 2006 - 09:02 AM

#12

I was afraid of that. Now this will turn into another oil thread.

I don't care for YamaLube for a couple of reasons. One is a little arcane, and that is that they haven't been SG/SH oils for a long time (last I saw they were SJ or SL), which should mean that they don't contain as much ZDDP anti-wear additive as I'd like. Apart from that, according to lab test results I've seen, it fails to maintain its viscosity very well in an ASTM D-6278 cycle. Several people have also found that while their clutch doesn't slip when running YL, it did act up by grabbing, chattering, or dragging until they switched oils.

There are a number of oils I believe are better in all of these regards, and I'd recommend looking through some old posts if you want to read more about it. There's been plenty written.

These are my reasons. They may not be right, they may not match up with anyone else's experiences, but they're mine. If it works for you, and you change it often enough, almost anything will do. I just happen to think that you can do better.

  • Zique

Posted September 06, 2006 - 09:48 AM

#13

Just to point a possible problem out. I've had the same thing happen before after I had been fiddling w/ the choke a bit. What happened was that the clamp holding the carb to the boot had come a little loose and fiddling w/ the choke loosened it up to create an air leak. What that tight when you took it apart?

  • grayracer513

Posted September 06, 2006 - 11:52 AM

#14

What happened was that the clamp holding the carb to the boot had come a little loose and fiddling w/ the choke loosened it up to create an air leak.

That's a good point. The clamp has a sleeve around each of the bolts that prevents them from being over tightened. This backfires when the isolator (mounting sleeve) shrinks from age and can't be tightened any more. Don't be tempted to remove or shorten the sleeves. Replace the isolator if it's not tight when the clamps are run all the way down.

  • GONE1445

Posted September 06, 2006 - 12:55 PM

#15

It seemed tight to me I had to pull pretty hard to get the air box off and on the engine side I could feel it kinda snap on if you will so I dont think the isolator is wore out but the clamps may have been loose I didn't pay attention to it

so now I am just waiting for my cables and air filters to get here

also what sprokets do you recommend for the chain my uncle gave me his off his 2003 YZ450f because he changed it out when he bought it so there are no rides on it should I get another chain or just use this till it wears out??

  • SureBlue

Posted September 06, 2006 - 01:38 PM

#16

also what sprokets do you recommend for the chain my uncle gave me his off his 2003 YZ450f because he changed it out when he bought it so there are no rides on it should I get another chain or just use this till it wears out??

Your uncle changed the stock chain right from beginning, so why should you use it, it is junk. Instead of ruining your new sprockets with an inferior stock chain, get a quality chain, several posts written about this too.
Ironman sprockets and a DID or Regina chain can be recommended.
http://www.qualitysm...man/ironman.htm

  • GONE1445

Posted September 06, 2006 - 03:25 PM

#17

good point I just figured if it was free might as well but I guess not

any who if I buy fork springs from MX-tech do they come in pairs or seprate I assume they come in pairs but wanna make sure(I know its not the suspension area but thought I would as here instead of starting a new thread)

  • grayracer513

Posted September 06, 2006 - 04:21 PM

#18

also what ... do you recommend for the chain my uncle gave me his off his 2003 YZ450f because he changed it out when he bought it...

Make jewelry out of it and sell it to the skinheads.

If you know someone with a Honda CRF150, they might be able to run it for a while.

  • GONE1445

Posted September 09, 2006 - 11:18 PM

#19

oh yea I for got to ask will an exhaust leak cause these symptoms to happen

I think the gasket between the head pipe and muffler is loose dunno

  • SureBlue

Posted September 09, 2006 - 11:55 PM

#20

Yes it can, or intake leak or a clogged pilot jet, these mean more air in the fuel, thus popping.





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