Two Brothers Racing Honda XR50R - Manual

Mfg: Honda Make: XR50R Year: All
Product: 81.2cc E-Stage Bore Up Kit (part # 010-1-05-522)
88cc S-Stage Bore Up Kit (part # 010-1-05-502)
Warranty
Two Brothers Racing products are intended for closed course competition purposes only, and therefore are sold “as
is” without warranty. Two Brothers Racing specifically disclaims any warranties of merchantability or fitness for a
particular purpose and disclaims all responsibility for consequential and incidental damages or any other losses
arising from the use of these products or parts.
We recommend that this performance engine kit be
installed by a qualified motorcycle technician. If you
have any doubts as to your ability to install this per-
formance engine kit, please consult with your local
motorcycle dealer. Read all instructions first before
starting installation. Make sure the motorcycle and
exhaust system are completely cool before starting the
installation. Also, make sure the bike is secure on the
sidestand or ideally a rear service stand during installa-
tion. Be sure to save all stock components for possible
use later.
1. Shut off fuel petcock
Remove the stock manifold
Remove air cleaner assembly
Remove the fuel and air hoses from the carburetor
2. Remove stock exhaust system
3. Remove spark plug
4. Remove cylinder head cover
Remove left side cover
IMPORTANT - PLEASE READ CAREFULLY
XR50R 88cc Engine Build Instructions.qxd PAGE 1
88cc S-S
tage Kit shown
Disassemble the Stock 50cc Engine
Parts List
81.2cc E-Stage Kit &
XR50 Stock 88cc S-Stage Kit
Bore 39.0mm 50mm (E), 52.0mm (S)
Stroke 41.4mm 41.4mm
Compression Ratio 10.0 : 1 11.5 : 1
Intake Valve 19.0mm 19.0mm
Exhaust Valve 16.0mm 16.0mm
Intake & Exhaust Valve clearance should be 0.05mm
(+/- 0.02mm tolerance)
Technical Specifications
Warranty
81.2CC E-STAGE 88CC S-STAGE
QTY. DESCRIPTION PART NUMBER PART NUMBER
1 CYLINDER N/A 010-1-02-02
1 PISTON 010-1-02-522 010-1-02-502
1 CAMSHAFT N/A N/A
1 PISTON RING SET 010-1-15-018 010-1-15-014
2 C-CLIPS N/A (INCLUDED W/ PISTON) N/A (INCLUDED W/ PISTON)
1 WRIST PIN N/A (INCLUDED W/ PISTON) N/A (INCLUDED W/ PISTON)
1 GASKET KIT 010-1-13-023 010-1-13-050