Engine stalling YZ426F 01

Hi Guys

I`m having an annoying problems with my YZ. It tend to stall very reguraly.

It usually appends went riding tight wood trails, I shutoff the throtle (while stopping for a thechnical section) and it stalls. I tried raising the idle a bit but it doesn`t seem to work.

It seems to happen more frequently now, I`m getting very annoyed and tired or kick starting the thing.

Any ideas



Get a Flywheel wieght or you will stall, and stall, and stall it. I know, I went through the same deal. I put on a 14oz. Steahly flywheel weight and it changed my bike completely! Its awesome. I have not stalled my bike in months. It was the best $200 I ever spent. It was an instant change with no noticable affect on power. The bike still snaps and RRRIIIPPPSS!! Do it before you get further frustrated. It is literally a 20m minute change and extremely simple.

Roostn in Golden

Thanks for the info on the flywheel, my fear was that the bike would not be as snappy as it is right now.

I also suspect that the valve are out of spec, it`s not stalling while trying to get going but when clutch is fully release.(level to the handlebar) and yesterday when I try to start it I took 3-4 kick before getting compression... oups... hope it`s only a valve adjustment



You may have some carb jetting problems, a smaller coutner sprocket should help too. Check you compression release lever and make sure it has play in it so it dose not leave the release open at all.

Also check clutch adjustment if you"re clutch is dragging and you lock up the rear brake this = stall!! I too am having similar problem with my 00 yz and i have the flywheel weight. It seem that the bike likes to stall on downhill switchback type turns where i brakeslide the rear end around. The moment i get on the gas the bike coughs and dies. This gets frustrating especially in the middle of a race. I too have increased my idle speed (doesn't help). I am starting to doubt myself and wonder if it is do to rider fatigue and being lazy with the clutch lever? What octane gas are you running? BTW the flywheel weight helps to smooth out the power delivery not slow it down. The snap is still there and it finds traction like a badger making a new home.

Flameout blues, Huge

To add to the above advice. If it seems as though the bike is tending to stall more now than before, then something is gradually changing. It's possible that the bike is not at fault and you are becomming adjusted to the bike and it stalls more because of an assumption on your part. Barring that, and not meaning to blame you, it might be that the engine is slowly changing it's state of tune. As you have suggested, it's highly possible that the valve lash is out of spec. Most likely a valve or two are tight. Another possibility is that the carb is overdue for a thorough cleaning...especially the pilot jet circuit since the pilot jet controls the idle to 1/4 throttle. Pump gas tends to leave a brown syruppy residue that restricts the pilot jet and causing a lean mixture. If the restriction is great enough, the engine becomes quite finnicky. The symptoms are, generally hard starting...won't idle....exhaust popping when the throttle is closed from high revs(if you can get it to run)...only runs at higher revs. Sound familiar?

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