Wr400 timing chain replacement
Posted January 18, 2015 - 07:54 AM
Posted January 18, 2015 - 11:25 AM
- Remove the cam cover
- Remove the left side crankcase cover ("flywheel cover")
- Remove the magneto rotor ("flywheel")
- Remove the magneto stator
- Position the engine at TDC on compression (cam lobes will be pointed upward and outward)
- Remove the timing chain tensioner
- Remove the cam caps and both cams
- Remove the two bolts securing the bottom of the rear tensioner guide shoe
- Remove the old chain buy rotating it so one side will pass over the end of the crank, then pull up and out
- Lower new chain down the tunnel, rotate vertically to loop over crank. Position crank at TDC using probe through plug hole to locate TDC.
- Loop chain over exhaust cam and position cam in saddle in head. Align timing mark with slack between cam and crank pulled taut on front side.
- Loop cam over intake cam. Place cam over head and roll cam into place in its saddle. Check alignment of timing marks and adjust as required
- Reattach bottom end of tensioner shoe
- Reinstall tensioner (see manual for instructions for resetting tensioner.
- Recheck timing and correct as necessary.
- Reinstall cam caps, carefully retorquing cap bolts to 75 inch pounds (6.5 ft/lb) in proper sequence and in 3 incremental steps
- Reinstall stator, flywheel, crankcase cover, and cam cover.
Download a manual:
If you cannot access a manual for your 400, use the oldest available manual for any YZ426 or YZ450 up to 2005. The procedure is fundamentally identical.
Posted January 18, 2015 - 10:47 PM
Posted January 20, 2015 - 07:07 AM
Not on the 400, no. It seems to me there's more than one answer to that question on the earlier models. But that's not the important thing, and it's not how cams are timed. It is helpful when you're assembling the second cam into the chain, but it doesn't tell you how the cams relate to the crank, which is what timing is all about. Align the marks to the head best possible with the crank in the correct position, and the timing is set.