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how much to touque a 400ex head
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Posted by:

i have my 400 apart to put new pistn in. does anyone know how much to tuorque it back down? i need to know the cylinder, middle, and top parts of the head. also the clutch cover. does anyone know? thanks

Posted by: yamaha1470

here are all the specs from the ex tech

Maintenance

spark plug -- 13 lbf-ft
valve adjusting hole cap -- 11 lbf-ft
valve adjusting lock nut -- 17 lbf-ft
crankshaft hole cap -- 5.8 lbf-ft
timing hole cap -- 7 lbf-ft
engine oil drain bolt (crankcase) -- 18 lbf-ft
engine oil drain bolt (oil tank) -- 14 lbf-ft
engine oil strainer screen (at oil tank) -- 40 lbf-ft
oil pipe joint flare nut -- 14lbf-ft

Cylinder Head/Valve

cylinder head cover bolt -- 17 lbf-ft (NOTE; Chuz emailed me to let me know that this spec in the service manual is incorrect.... the correct spec is 8 lbf-ft, not 17... thanks Chuz!
rocker arm shaft -- 20 lbf-ft
intake sub-rocker arm shaft -- 20 lbf-ft
exhaust sub-rocker arm shaft -- 20 lbf-ft
cam sprocket bolt -- 14 lbf-ft
cam tensioner plug -- 2.9 lbf-ft
cylinder head nut -- 33 lbf-ft

Cylinder/Piston

cylinder bolt -- 33 lbf-ft
cylinder stud bolt -- 33 lbf-ft

Clutch/Gearshift Linkage

clutch center lock nut -- 80 lbf-ft
primary drive gear nut -- 65 lbf-ft
gearshift drum stopper arm pivot bolt -- 9 lbf-ft
gearshift spindle return spring -- 17 lbf-ft

Altenator/Starter Clutch

flywheel bolt -- 94 lbf-ft
starter clutch bolt -- 22 lbf-ft
left crankcase cover stud bolt -- 7 lbf-ft
gearshift pedal pinch bolt -- 14 lbf-ft

Crankcase/Transmission/Crankshaft

mainshaft bearing setting plate bolt -- 9 lbf-ft

Lights/Switches

neutral switch -- 9 lbf-ft

Posted by: VegasEx'r

For the cylinder head cover bolts, there is a large bolt (8mm I think but can't remember) in the middle. That should be 17 ft-lbs, the rest (6mm I think) should be 8.