Valve Check; When
Posted February 24, 2005 - 02:58 PM
Posted February 24, 2005 - 06:45 PM
Posted February 24, 2005 - 07:47 PM
Posted February 24, 2005 - 08:20 PM
Then use these directions and you should be fine:
YZ250f/400/426, WR250f/400/426 Valve Adjustment Procedure:
Remove seat, tank and shrouds
Remove breather hoses from top of engine cap.
Remove the spark plug.
Remove the top engine mount brackets (12mm, 14mm and hex wrench needed)
Remove the two engine cap screws (hex wrench needed).
Remove the engine cap taking care not to damage the gasket.
Remove the two timing caps from the left side of the engine crankcase (standard screwdriver)
Using a 14mm socket, align the timing mark ("I" not the "H") with the marks on the cover for the compression stroke (cam lobes should be facing away from each other). The marks on the cams should also match up to the top of the engine per WR or YZ timing.
Using a feeler gauge, you should be able to check all your valve clearance numbers.
Start with the manual specs and shove the feeler gauge under the cam lobes. If it won't go under, go down until it does. If it goes in to easy, go up. I beleive there should be a slight resistance when checking the correct clearance but it should slide under the lobe.
Compare your numbers with the manual's specs. If they are not in specification, then you will need to change out your shims.
Make sure you keep track of which clearance measurement goes with each valve as you will have to match them up with shim numbers if you need to adjust them. That is all you need to do to check your clearance.
Posted February 24, 2005 - 08:29 PM
I have 300+ hours on my 03' WR450 and I have the valve clearance checked once a year in the Spring. The only time one of the five valves was too tight was right after break-in in 03'. I short shift most of the time and don't over-rev the bike. I suspect the piston rings and/or valve springs will wear out sooner or later. If it's the latter case I bet I'll have a valve job, or worse, on the horizon. $$$$$ Time to trade in?
I could ask how many hours on a bike like the 450 can a rider expect before he should consider a new bike? The manual leads me to believe the motor should have been rebuilt many hours ago.
Posted February 24, 2005 - 08:55 PM
Posted February 24, 2005 - 08:57 PM
But then again there are people that buy a new bike every so many years like it is clapped out or something. Which is cool if you can handle the constant payments I am thankfull for my Blue beast and just enjoy what I have and worrie about a new bike if ever I need it at that time. Thats me though
Posted March 04, 2005 - 02:31 AM