01' 426 acting lean but its not


13 replies to this topic
  • Jizz

Posted November 10, 2006 - 09:48 AM

#1

I have an 01' 426 that i had jetted at dyno jet, and installed a baja designs lighting coil. the bike has run awesome for many years. I made a stupid mistake and loaned the bike to a good friend. he said he stalled the bike and couldn't get it started again. i got it back and put a new plug in it and got it started but it ran like crap. at top end it would sputter and when i let off the gas it would pop. I've rebuilt the carb and saw nothing it could have been. Could it be ignition? timing? weak spark? thanks for all your help.

  • PK

Posted November 10, 2006 - 12:38 PM

#2

If it's acting lean, your looking at an air leak from somewhere. Is your hot start working normally? If the plunger freezes up in the carb it will cause it to run similar to what your describing. Did the guy hammer the bike when he rode it? Ignition problems wouldn't generally cause what you have mainly because the bike runs and starts. A weak spark would make it very hard to start. Have you checked to see if your fuel screw fell out? Make all your carb attachments are tight also (boots and manifold)

  • Jizz

Posted November 10, 2006 - 02:24 PM

#3

no he didnt hammer it, and ive checked for air leakes. ill take the hot start out again and check that. thanks for your help

  • YZ426F Rider

Posted November 10, 2006 - 04:10 PM

#4

This will not help you with your problem but I learned many many years ago to NEVER EVER loan a bike out. EVER. Twice I've had bikes returned to me with seized motors (two strokes). One guy tried to restart it by towing it behind a pickup...for a mile! Then, during rebuild time he says that it was bound to happen anyways and he wasn't going to help with the cost.

As a matter of fact my cousin is a little pissy with me right now because I have five bikes and won't let him borrow one to learn how to ride. He thinks I'm being selfish but &%$#@!...why would I want someone that has never ridden to learn on one of my bikes???

  • Jizz

Posted November 10, 2006 - 05:23 PM

#5

Believe me. Ive learned my lesson!

  • PK

Posted November 11, 2006 - 11:28 AM

#6

One way to chase down an air leak is to spray starting fluid around the area you suspect may be leaking. When it is sucked in, the idle speed will increase. Obviously with a dirt bike you have to worry about the hot exhaust but you can cover the area with aluminum foil.

You can check the hotstart by starting the bike and pull it, the idle speed will change if it's working. I had a remote hot start on my 99' 400 that froze up in the out position and the bike ran like crap.

We all learn lessons in different ways. There are a few people I would let ride my bike but only because I know they treat their own stuff with care. There is always my golden rule, you break it, you buy it. Sometimes thing break though and it may have had nothing to do with who was riding it. It's a personal call and I sure wouldn't lose any sleep over it.

  • Florida_426

Posted November 11, 2006 - 05:57 PM

#7

My one experience with this was caused by the nitrile gasket between the intake bell and the back of the carburetor body. One little place out of the groove allowed enough air to drastically lean the bike out. New gasket and all was well.

Bill

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  • sirthumpalot

Posted November 12, 2006 - 07:05 AM

#8

Not knowing what happened to the bike, stick with the basics. When you cleaned the carb, did you put cleaner followed by compressed air thorugh all the jets and little holes? How does it start and idle? Take 2 seconds and check the timing. If the motor has some hours and he was really bad about starting (i.e. tried to push start or let it spin backwards a little bit, etc..) it's not impossible that the cam chain jumped a tooth. Grab the electric meter and check out your coil and stator, see if they measure in spec. That's the most I can think of at the moment..

  • GONE1445

Posted November 12, 2006 - 10:04 AM

#9

might be a clogged jet that is what happend to me

  • Jizz

Posted November 12, 2006 - 11:11 AM

#10

Not knowing what happened to the bike, stick with the basics. When you cleaned the carb, did you put cleaner followed by compressed air thorugh all the jets and little holes? How does it start and idle? Take 2 seconds and check the timing. If the motor has some hours and he was really bad about starting (i.e. tried to push start or let it spin backwards a little bit, etc..) it's not impossible that the cam chain jumped a tooth. Grab the electric meter and check out your coil and stator, see if they measure in spec. That's the most I can think of at the moment..

Before i didnt have to pull the choke to start it but now i do and it runs ok but not as good at idle. the bike has got some hours but never had a problem starting it. how do you check the timing? how do you check the stator and coil? thanks for your help!

  • Fastest1

Posted November 12, 2006 - 02:23 PM

#11

Has the temperature dropped significantly since you had last ridden it? I wouldnt think so in Nevada but I could be wrong. It would explain the choke.

  • Jizz

Posted November 12, 2006 - 03:03 PM

#12

Has the temperature dropped significantly since you had last ridden it? I wouldnt think so in Nevada but I could be wrong. It would explain the choke.

its dropped a little. but i have had this same configuartion for years with no problems.

  • sirthumpalot

Posted November 12, 2006 - 05:29 PM

#13

The manual will show you how to check the timing step by step, but it's really easy. Basically clean up the bike, especially under the tank area. Remove the valve cover and the two plugs on the flywheel cover. Remove the spark plug too (to make the engine easier to turn). Line up the marks down below and the marks on the cams should line up as well (see the manual). Also verify by checking the position of the cam lobes, it's not unheard of for a cam sprocket to slip on the cam. If the marks up top aren't lined up, spin the engine over one revolution and check them again; remember the engine turns 2x for every time the cams turn 1x.

To check the stator and coil, again see the manual. In short, you'll get a good resistance meter (Ohms, digital are easier to use) and connect it to a few specific wires then compare your readings to those in the manual. I hope this helps!

  • Jizz

Posted November 12, 2006 - 08:28 PM

#14

The manual will show you how to check the timing step by step, but it's really easy. Basically clean up the bike, especially under the tank area. Remove the valve cover and the two plugs on the flywheel cover. Remove the spark plug too (to make the engine easier to turn). Line up the marks down below and the marks on the cams should line up as well (see the manual). Also verify by checking the position of the cam lobes, it's not unheard of for a cam sprocket to slip on the cam. If the marks up top aren't lined up, spin the engine over one revolution and check them again; remember the engine turns 2x for every time the cams turn 1x.

To check the stator and coil, again see the manual. In short, you'll get a good resistance meter (Ohms, digital are easier to use) and connect it to a few specific wires then compare your readings to those in the manual. I hope this helps!

thank you very much. much appreciated.





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