Checking and adjusting valves
From: SMTP%"lawas@analog.com" 24-JUL-1995 10:00:23.24
To: MEL1523
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Subj: Hawk Valves
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Date: Mon, 24 Jul 95 10:51:14 EDT
From: lawas@analog.com (Ken Lawas x2631)
To: HawkGT@dsea.com
Subject: Hawk Valves
> Well, I just adjusted the valves on my '89 today. What a pain. All
> was going well until I tried to take off the front valve cover. Is
> there a secret to getting this off?
Here's something I wrote up earlier this year. The front cover was
a pain because I didn't unbolt enough stuff. Removing what I list
here works OK.
----- Begin Included Message -----
NT650 Valve adjustment.
As told by Ken Lawas. Source: Factory service manual and
frustrating experience.
Adjust every 8000-miles, although all six were under on my
bike after 4300-miles.
MINIMUM TOOLS I'D BRING
10mm combination wrench, 10mm 3/8-in long and short sockets.
Needle-nose pliers. Socket cap screw 3/8-in sockets. Philips
driver #1. Socket (17mm?) 1/2-in and drive to turn crankshaft.
Regular 3/8-in drive and 3/8-in torque wrench (7 to 17 ft-lb).
Feeler gauges (0.006 and 0.008-in at least). Ignition wrench
set (I think the adjustment screws are about 5/32-in). Did I
use a 9mm wrench for something? Various 3/8-in extensions
with different reach 10mm sockets were needed to use torque
wrench on each lock nut.
PREP
1. Remove seat (with key).
2. Remove tank (rear bolt, front bolt, then thread rear into
front pin and pull. Fuel lines-turn off petcock.)
3. Remove airbox (front nut on stud, unclip wiring harnesses,
remove purge lines, unclamp from carb throats.)
4. Remove horn (one bolt--clearance needed for radiator).
5. Remove radiator mounting bolts. (two in bottom, one in double
shear at top with nut). Careful--mounting bracket is weaker
than torque needed to shear Locktite.
6. Remove mounting stud for thermostat (same stud as air box).
7. Remove fan mounting bolts (three) and electrical connector.
8. Remove inset plug wires (one from each cylinder).
9. Remove the two valve-cover mounting bolts from each cover.
10. Remove valve covers. Rear is obvious. Front must be carefully
snaked under thermostat, through the front of the frame, rotated
down behind radiator (fan moved aside) and pulled out horn-side.
At least this is how I managed to do it. You may be able to
leave the fan and horn in place, but it isn't worth it.
11. Remove crankshaft bolt cover and timing mark cover (left side
of crankcase).
ADJUSTMENT
1. Turn crankshaft counterclockwise until timing mark is aligned
(FT for front cylinder, RT for rear). Cylinder must be on
compression stroke (all three valves closed). You can feel the
compression when turning the crank. Double check by noting that
followers are not on cam lobes and there is free play between
valve and adjustment screw. If not, make another 180-degree
rotation of crank.
2. Measure clearance. Push down on cam-side of rocker and note
largest feeler that will slide between screw and valve without a
lot of friction.
Exhaust should be 0.008-in and intakes should be 0.006-in (give or
take 0.0008-in). (The two intake valves are on the carb side of
the head. The one exhaust valve is on the exhaust header side of
the head.)
4. If adjustment is necessary, loosen lock nut on valve adjustment
screw. Press rocker against cam and adjust screw so that the
appropriately-sized feeler slides over the valve stem with minimal
friction. Hold the adjustment screw and tighten the lock nut.
This is what the manuals say. Reality is that the adjustment
screw turns a little when you torque down the lock nut. I had
luck adjusting the screw until the next highest feeler just fit,
then hold the adjustment screw and crank the lock nut down with a
combination wrench. Now, set your torque wrench for 17 ft-lbs and
torque down the lock nut. Measure the clearance again. You will
often get lucky and it comes out just right.
5. Clean the valve cover gasket mating surfaces and apply a thin film
of oil.
6. Replace the covers and torque the bolts to 7.2 ft-lbs.
7. Apply anti-seize to the crank bolt cover and timing mark cover
plugs and tighten them down to 7.2 ft-lbs.
8. Replace everything. I used threadlocker on the upper radiator
mounting bolt.
----- End Included Message -----
> Make sure you don't overtighten this cover bolt. Spec says only 11
> ft/lbs.
I thought it was 7.2 ft-lbs, but maybe I made a mistake.
-Ken
kenneth.lawas@analog.com
'90 Red
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