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Zephyr Manual Cam Chain Tensioner
Installing the new manual cam chain tensioner:
- You will need a pair of 13mm wrenches, a 4mm hex key (allen
head) wrench or socket, ratchet, inch/lb torque wrench, gasket sealer, an
appropriate size socket/ratchet to turn over the engine.
- You may or may not have to remove the carburetors to do the
installation, I had them off so it was no problem. Adjustment can be made with
the carburetors on the bike.
- Remove the “automatic” tensioner body from the motor by
removing the two small bolts.
- Remove the Zephyr right side crank cover, easiest side to
work from.
- Back the adjustment bolt out a fair amount on the new
tensioner and remove the plastic sleeves from the mount bolts
- Put some Yamabond (Hondabond, Kawabond – whatever bond)
sealant or a similar goop on the tensioner gasket. I don’t know for sure, but
even grease may work fine.
- Install the tensioner in place threading in the supplied
countersunk bolts. On the Zephyr just install the tensioner either direction.
The adjuster bolt is centered so there is no difference.
- Torque the bolts to 72 in/lb (6 ft/lb or 8 N/m) if you
wish, I just used a 4 mm allen wrench and my “torque wrench arm”… if you know
what I mean.
- Turn the adjuster bolt in as far as possible by hand.
- Using the appropriate socket and ratchet on the bolt in the
end of the crank shaft,
A) From the right side, rotate the crank shaft clockwise slowly,
which will pull the cam chain taut on the drive side making the tensioner side
slack, while turning the tensioner adjustment screw by hand. DO NOT spin the
motor over with the starter, you risk jumping cam timing or possible valve
damage due to excess chain slack.
B) Turn the motor over for a few revolutions while applying
pressure by hand, The tensioner bolt will turn in easily when taking up slack
in the chain, but will resist turning when either the chain is under tension
(turning the crank the wrong way) or when the slack has been taken up.
C) You should be able to tell when the slack is gone, the bolt
will no longer turn easily.
D) Back off 1/6 turn (one flat of the acorn nut).
E) Using one 13mm wrench snug the tensioner locking nut down tight
while holding the acorn nut with the other 13mm wrench.
F) Rotate the crank slowly over again to make sure valves are not
out of time and hitting the pistons.
- Start the engine and warm it up to operating temperature.
- With the engine running, listen for any chain noise.
A) Tighten the tensioner bolt back in slightly (about 1/8 turn or
less) until rattle is gone.
B) Tighten the locking nut while holding the tensioner nut in
place with a wrench to keep it from turning.
This works without gimmicks and guesswork that can over
tighten the chains or let them flail around in the cases. Re-adjust every
several thousand miles or if you hear the rattle of cam chains again. I think
I’ve only done about 4 adjustments over the past 25,000 miles using the “sound”
method on the KLX. I didn’t need any change in adjustment on the Zephyr after
installation. The key point is what the tensioner does – it simply takes up
excess slack so the chain(s) don’t slap around and wear prematurely. There is no
preloading necessary.
Install the tensioner and take out the slack
by turning the crank while tightening the adjuster nut by hand.
Take off the right side crank shaft cover and rotate the crank shaft
clockwise using a 13 mm socket and ratchet or breaker bar.
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