Book Excerpt: 1978-1984 Honda XL250, XR250, XL500, XR500 Repair Manual
ENGINE, CLUTCH AND GEARBOX
ENGINE REASSEMBLY: SETTING THE BALANCER CHAIN TENSIONER
Once the crankshaft halves have been assembled, the balancer chain tension should be set to provide the correct operating conditions for the chain and sprockets.
To achieve this, it is necessary to vary the distance between the front and rear balancers, and it is for this purpose that the front balancer holder is provided.
The front balancer shaft runs in the eccentric bore of a tubular holder. The right-hand end of the holder terminates in an adjuster plate which is located by a single retaining bolt.
When adjustment is necessary the holder is rotated in the crankcase, effectively moving the axis of the front balancer shaft forwards or backwards.
To adjust the chain tension it will first be necessary to fit the adjuster spring to the adjuster plate or flange. Check that the holder moves freely in the casing and turns fully anti-clockwise under spring pressure. Check that the chain is tensioned in this position.
The lower edge of the adjuster plate is marked by a series of lines. The balancer chain tension is set by moving the adjuster plate back (clockwise) by one graduation from the fully tensioned position. Holding this position, refit and tighten the locking bolt to 16-20 lbf ft (2.2-2.8 kgf m).
Occasionally it may prove impossible to obtain sufficient adjustment within the range of movement provided by the elongated slot.
If this proves to be the case it will be necessary to move the adjuster plate in relation to the holder. Disconnect the adjuster spring.
Release the circlip which retains the balance weight, then slide the latter off the end of the balancer shaft.
Remove the plain washer which is fitted behind the adjuster plate to the holder. It will be seen that the adjuster plate is located by tangs which engage in corresponding slots in the holder.
Withdraw the adjuster plate and reposition it one slot further round (clockwise) to bring the range of adjustment within the scope of the plate.
WHEELS, BRAKES AND TIRES
FRONT WHEEL: REMOVAL AND REFITTING
As no centerstand is fitted, some alternative means of supporting the machine with the wheel clear of the ground must be found prior to wheel removal.
A stout wooden box or similar is usually suitable, but ensure that there is no risk of the machine toppling whilst it is being worked on.
Commence dismantling by slackening off the front brake cable adjustment at both ends, then disconnect the cable at the wheel after disengaging the cable at the operating lever. The speedometer drive cable should be released by its single retaining screw.
Straighten and remove the split pin (XL models only) which secures the wheel spindle nut, then remove the nut itself. Remove the clamp bolt(s) at the other end of the spindle, then withdraw the spindle and lower the wheel clear of the forks.
With the wheel removed from the machine, the brake backplate assembly can be removed for examination. Refer to next section for brake inspection.
The wheel may be refitted by reversing the removal procedure. When lifting the wheel into position ensure that the lug on the left-hand fork leg engages with the slot in the brake backplate. If this requirement is overlooked the brake will lock on the first application.