Two Brothers Racing Honda XR50R User Manual
Intake & Exhaust Valve clearance should
be 0.05mm (+/- 0.02mm tolerance)
Once valve clearance has been set rotate
engine COUNTERCLOCKWISE twice and
realign the "T" and "O" marks
Recheck valve clearance again if there is
no gap you have done everything correct-
ly, if you find a gap reset valve clearance
and turn over engine COUNTERCLOCK-
WISE twice. Repeat until proper valve
clearance is accomplished.
Reinstall all remaining engine covers
7. Install left side cylinder head gasket and cover
Be sure to fully tighten left side cover, tab
Tighten right cylinder head hex bolt, torque to
9 ft lbs.
8. Install spark plug.
9. Reinstall exhaust system.
10. Install new carburetor and air filter (if pur-
chased). Be sure not to over oil the air filter. If
you have purchased the 81.2cc E-Stage or
88cc S-Stage COMBO KIT you will have an
exra #85 main jet for your Keihin PC18 carbu-
retor. Try either the #85 of the #92 (already
installed in carburetor) before calling tech sup-
11. Install left engine cover. Reinstall gear shift
lever, torque to 1.0kg-m
12. Double check your work before starting
the bike and double check the engine oil
things to double check to ensure
proper operation of your Takegawa
81.2cc E-Stage or 88cc S-Stage Kit.
Please check IN ORDER as that they
appear on this list:
1. Double check the timing. The cam gear must
be aligned on the “O” mark/hash mark on the
head of the motor. This hash mark can be
found at the 9 o’clock position.
The flywheel must be aligned on the “T”
mark/hash mark on the engine case. This
hash mark can be found at the 12 o’clock
2. Double check the valve clearances.
If you have metric tappet gauges the clear-
ance is .05mm (intake & exhaust).
If you have american tappet gauges the clear-
ance is .002” (intake & exhaust).
3. Be sure you properly reattached the ground
wire and it is touching bare metal. This step is
often overlooked when installing a new carbu-
4. Do not over oil the air filter. To much oil on the
air filter will cause your bike to run very poor-
ly. Only a minimal application of oil is ever
5. Be sure your carburetor is properly jetted,
refer to the last page of these instructions for
jetting tips. To ensure maximum performance
be sure to use a Two Brothers Racing XR50
exhaust system (part # 005-300104). Using
the stock exhaust system or a different after-
martket exhaust systemwill not allow optimum
Baseline settings (you will need to adjust
these settings to fine tune your carbure-
tor). These setting are for use with the Two
Brothers Racing exhaust system.
Main Jet: #85 or #92 (try both main jets!)
Air Screw: 1-1/2 turns from botton
Needle Clip: middle position
XR50R 88cc Engine Build Instructions.qxd PAGE 6