I
I
I
Brake adjustment
- As the brake pads wear, adjustment to the caliper will become
necessary to restore proper freeplay at the brake lever. A stroke of about 5-10mm
should be obtained as measured at end of the caliper lever. To make this adjustment,
unscrew caliper arm nut (2) and rotate threaded shaft (1) clockwise with a 2.5mm
allen wrench until the correct stroke of the caliper lever is restored. Then, while
holding the threaded shaft against rotation, tighten the caliper arm nut (2) again (to
60 in./lbs
), and check that the wheel is not dragging or locked. Make final adjust-
ments at the brake lever adjuster as needed. See illustration III.1
Front brake caliper service
Support bike on stand with front wheel off ground. Remove front wheel. Loosen
cable clamp screw using a 2.5mm allen wrench while holding cable clamp body
with an 8mm wrench. Remove cable from arm. Be careful not to lose cable clamp
assembly. Caliper will now slide off pins on mounting bracket. Remove two pad
retaining bolts using a 3mm allen wrench and remove pads. Remove caliper lever
using a 8mm wrench to remove retaining nut. Note position of lever spring.
Remove two caliper housing bolts using a 4mm allen wrench. Push on lever shaft to
remove caliper piston from housing, make sure not to lose two small rollers. Remove
cylinder from center of piston. See photo III-4.
Clean caliper housings thoroughly, especially the piston bore. Clean piston assembly and make sure allen screw turns freely.
Lubricate allen screw and piston cylinder carefully so excess lubricant does not end up on pads or disc. Lightly grease two rollers
and insert them into piston bore, using a little grease to hold them in place. Lightly grease ramps on back of caliper piston and insert
piston back into caliper housing. Assemble caliper housing using two bolts, torque to
XX ft/lbs
. Then insert pads with friction mate-
rials facing each other and install two pad retaining bolts and torque to
XX in/lbs
. Install lever spring and caliper lever and loosely
install nut to retain lever. Push caliper onto mounting pins and reinstall front wheel. Spread pads to insert disc between pads. If disc
will not fit between pads, turn allen screw on caliper lever shaft counterclockwise to loosen pad adjustment. Attach brake cable to
caliper lever and adjust caliper free play. Tighten caliper lever retaining nut to 60 in/lbs. Adjust cable position and brake lever as
needed.
Rear brake caliper service -
Support bike on stand with rear wheel off ground. Remove rear
wheel. Proceed with service as for front brake caliper. Note that rear brake mounting bracket slot must
engage pin on swingarm to prevent rotation, and that pedal freeplay is adjusted only at the caliper.
10. Expansion pipe & silencer, repacking
The exhaust system on your Polini needs regular service to properly quiet the bike and maintain
peak power. The silencer uses fiberglass packing to reduce sound. If the packing becomes saturated
with oil, or burnt and fragmented the exhaust gases will be much more turbulent in the silencer
which will noticeably reduce power output as well as making the bike much louder.
The expansion pipe should be checked for cracks and large dents on a regular basis. Small dents
on the pipe will not affect power much unless they are located within 6-8 inches of the cylinder.
Make sure to replace the o-rings on the pipe when servicing motor. If the o-rings leak, power will
be reduced in addition to the mess leaking oil will cause. When pipe is removed, check inside of pipe where it joins the cylinder for
deposits of oil and carbon. Remove any deposits with solvent and a scraper. If cracks or holes are found, have welded or replace
pipe. Most dents can be fixed by companies specializing in this service. Make sure pipe mounting spring(s) are in place and tight.
Front caliper assembly
III
III
.3
.3
lever
arm
hold “nut”
and loosen set
screw to adjust
cable
rollers
III
III
.4
.4
III
III
.5
.5
Grease ramps and rollers &
lubricate adjusting screw
grease
lube
Exploded view of caliper assembly.
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