Yamaha Dirt Bikes Forum

I need a little advice . . . I just finished fixing a bad crank seal (thanks to the excellent troubleshooting advice of Drinky Chinky . . .), and after replacing the magneto, tried to line up the timing marks per the manual (rotate piston to TDC, and then clockwise rotate the mag rotor such that piston is 0.008" before top dead center, and then rotate stator plate until mark on rotor lines up with mark on stator. It just doesn't work. Not enough slop on the 3 stator mounting screw slots. It seems to line up if I rotate the rotor counter-clockwise, until the piston is 0.008" down from TDC, but that is opposite of what the Yamaha manual says. Any ideas?? Aftermarket crank from Hotrod? and factory magneto (both stator & rotor). I have a timing light but haven't tried it yet. Thanks all for your help.  

What the hell is a yz250m?  

2000 model year 2-stroke YZ250

  (99's are L's, 01's are N's I think . . .)  

How close would u say u were to getting it? Are u using a dial indicator off a tool mounted in the spark plug hole or are u checking it with the head off and measuring off the piston dome?  

I'd say very accurate - 1/4" drive ratchet extension through the spark plug hole, straight down onto the dome, pushing up onto a good dial gauge.

She ran pretty good before (just changed crank/bearings/seals), with the stator mounting screws in roughly the middle of the slots. Now I've rotated the stator clockwise, to the edge of the slots, trying to get the marks lined up. Not sure what's going on, or if it always been off a little. Is the light a better method? Is the .008" BTDC correct, or can that be changed a little?  Thanks much for your help.  

I may not understand exactly how ur doing this but I think there is a duration of crank rotation at TDC. If ur measuring off the dome without a degree wheel than u could be too far advanced when starting ur measurement fi that makes any sense??    

In the past when i've done seals I usually just mark the stator plat and put it back to where it was. Are u trying to change ur ignition timing or just want it where the book says?  

I'm just trying to make it proper.  You are right about the "duration" of crank rotation at TDC - it seems to be about 1/4" - 1/2" of rotor movement (at its perimeter near the marks). During this rotation of the crank, movement of the piston is imperceptible. I cna put her back to the middle of the slots and try it. Just wanted to get her perfect. Thanks again.  

I wish i could tell u about using a lite, but i have never tried one on a two stroke.  

arent there marks on the stator plate and case??
havent had the stator off of a yz in 10yrs. all my kx's were marked by the factory. and i just realigned them during reassembly.  

post count means nothing

06yz125,kx60(2)

I have a 95 YZ250 and it has marks on the case and plate,but if you replace the stator or flywheel you have to use a timing light to get it dialed in correctly.You should of made marks before removing the stator.Gonna have to use a lite if you want it perfect or go by the seat of your pants and put it where it runs best.