1961 TRIUMPH BONNEVILLE


1961 Triumph T120 Bonneville 650, Triumph motorcycles, Triumph TR6, Triumph Thunderbird



NEW MODEL DESIGNATIONS
Starting with the 1961 Triumph Bonneville, the T120 model designation was followed by either an "R" for Road models with low pipes, or a "C" for the Street Scrambler with high pipes. Changes in the new bike were minimal, yet the steady process of development and improvement never abated. Of course, again as always the T120 and the Triumph TR6 were styled alike, apart from the Triumph 6T Thunderbird with its more conservative looks.


ENGINE
Starting with Engine #D7727, the 1961 Triumph Bonneville got a new cylinder head casting with vertical pillars between the outer cooling fins, designed to stop high frequency ringing (the unsupported fins vibrated like tuning forks at high RPM). There were improvements made to the transmission (gearbox) including the replacement of plain bushing with needle-roller bearings on the layshaft. The gearbox itself was also anchored more securely in its mounts. The engine sprocket was reduced in size again from 22 teeth to 21 teeth and the gear ratios were juggled to lower the gearing even more, for better acceleration.

DUPLEX PROBLEMS
Problems with the duplex frame continued until all were either built with, or retrofitted with a second frame tube running under the main backbone, to brace the steering head, and the steering head angle (rake) was brought to 65-degrees. Most of the running gear was carried over from 1960. However, the rear tire-and-wheel size was increased. The Dunlop Universal was now a 4.00 X 18" and the rim a WM3-18.

SISTER BIKES
As would be standard practice for Triumph motorcycles from now on, the 1961 Triumph Bonneville was mostly the same as its sister-bike, the 1961 Triumph TR6, except with twin carbs.

BODY & PAINT
The fuel tank,oil tank and tool box were rubber-mounted to combat vibration. This year's new color was Sky Blue on top and Silver Sheen on the bottom separated by a gold pinstripe.

ELECTRICS
A lower-output alternator was introduced because bulbs had been blowing out at high RPMs. A new brake light switch (Type 22B) was fitted also. Otherwise, the 1961 Triumph Bonneville was pretty much a carry-over from 1960.

1961 Triumph Bonneville, Triumph Motorcycles, Triumph TR6

1961 Triumph T120R Bonneville Roadster w/down pipes.

1961 Triumph T120 Bonneville 650, Triumph motorcycles, Triumph TR6, Triumph Thunderbird

1961 Triumph Bonneville T120R. Pre-Unit Engine.

1961 Triumph T120 Bonneville 650, Triumph motorcycles, Triumph TR6, Triumph Thunderbird

1961 Triumph Bonneville T120C, Scrambler w/high pipes.

1961 Triumph Bonneville, Triumph motorcycles, Triumph TR6

1961 Triumph Bonneville T120C. Note skid plate & duplex downtubes.

1961 Triumph Bonneville, Triumph Motorcycles, Triumph TR6

1961 Triumph Bonneville T120C w/8" SLS front brake & knobby tires.


1961 Triumph Bonneville SPECIFICATIONS:



MODEL DESIGNATIONS:
1961 Triumph Bonneville T120/C.................... Scrambler
1961 Triumph Bonneville T120/R.................... Roadster

ENGINE:
Engine type....................................... OHV vertical twin
Horsepower at RPM............................ 46 BHP @ 6,500 rpm
Bore................................................ 71mm / 2.79"
Stroke............................................. 82mm / 3.23"
Displacement.................................... 649cc / 40 cu. in.
Compression Ratio............................. 8.5:1
Valve Clearance (cold):
Inlet................................................ 0.05mm / 0.002"
Exhaust............................................ 0.10mm / 0.004"
Valve Timing:
Inlet Valve Opens.............................. 34 degrees BTDC
Inlet Valve Closes.............................. 55 degrees BTDC
Exhaust Valve Opens.......................... 48 degrees BTDC
Exhaust Valve Closes.......................... 27 degrees BTDC

IGNITION:
Magneto Point Gap............................. 0.3mm / 0.120"
Spark Plug Gap.................................. 0.50mm / 0.020"
Timing (fully advanced):
Crankshaft position............................. 39 degrees BTDC
Piston position................................... 11mm / 7/16" BTDC

CARBURETORS:
Type................................................ Amal Monobloc
Throat Size....................................... 1-1/16"
Main Jet........................................... 240
Needle Jet........................................ .1065
Needle Position.................................. 2
Throttle Valve.................................... 376 / 3-1/2
Pilot Jet............................................ 25

TRANSMISSION:
Speeds.............................................. 4
Gear Ratios:
4th - Top........................................... 4.88
3rd - Third......................................... 5.81
2nd - Second...................................... 8.25
1st - Bottom...................................... 11.9
RPM @ 10MHP in Top Gear................... 638 RPM

CLUTCH:
Type................................................ Multi-plate, wet
Number of Plates:
Drive Plates...................................... 6
Driven Plates.................................... 5
Friction Material................................ Neolanglite

SPROCKETS:
Engine............................................. 22 teeth
Clutch............................................. 43 teeth
Gearbox.......................................... 18 teeth
Rear Wheel...................................... 43 teeth

CHAIN:
Primary, pitch.................................. 1/2" X .335" X 5/16"
Primary, length................................. 70 links
Final Drive, pitch............................... 5/8" X .400" X 3/8"
Final Drive, length............................. 101 links

CAPACITIES:
Fuel (US versions)............................. 3 Imp. gal.
Fuel (UK & export versions)................. 4 Imp. gal.
Oil Tank........................................... 5 pints / 3 L
Gearbox........................................... 2/3 pt / 400cc
Primary Chaincase............................. 1/4 pt / 150cc
Front Forks....................................... 1/4 pt / 150cc

TIRES:
Front............................................... 3.25 X 18"
Rear................................................ 4.00 X 18"

SUSPENSION:
Front............................................... Telescopic Forks
Rear................................................ Swing Arm

BRAKES:
Front............................................... 8" / 20.32cm SLS
Rear................................................ 7" / 17.78cm SLS

DIMENSIONS:
Seat Height...................................... 30.5" / 77.5cm
Wheelbase........................................ 54.5" / 140.3cm
Length.............................................. 85.5" / 202cm
Width............................................... 28.5" / 72cm
Ground Clearance.............................. 5" / 12.7cm
Weight, unladen................................ 393 lbs / 178kg


TRIUMPH MOTORCYCLE BOOKS


TRIUMPH RESTORATION, PRE-UNIT TALES OF TRIUMPH & MERIDEN

TRIUMPH MOTORCYCLES: TRIUMPH ENGINEERING CO.

TRIUMPH WORKSHOP MANUAL, 1935-1939

TRIUMPH WORKSHOP MANUAL, 1937-1951

TRIUMPH WORKSHOP MANUAL, 1945-1955

TRIUMPH MOTORCYCLES: FROM SPEED TWIN TO BONNEVILLE

TRIUMPH MOTORCYCLES - HINKLEY RENAISSANCE

SAVE THE TRIUMPH BONNEVILLE

THE INSIDE STORY OF THE MERIDEN WORKERS' CO-OP.
STORY OF THE TRIUMPH BONNEVILLE - MOVIE

TRIUMPH 650 & 750 TWINS

ESSENTIAL BUYERS GUIDE TO TRIUMPH BONNEVILLE

TR BONNEVILLE 2001-08

TR BONNEVILLE, PORTRAIT OF LEGEND

TR BONNEVILLE: T120/T140

TRIUMPH MC RESTORATION

HAYNES TR TRIPLES & FOURS

TRIUMPH 21 TO DAYTONA

TRIUMPH TIGER CUB BIBLE

Triumph Motorcycles
Triumph Bonnevilles
Triumph Bonneville, Pre-Unit Construction
Triumph Bonneville, Unit Construction
Triumph Bonneville, Oil-in-Frame

For more Great Books, please visit our
MOTORCYCLE BOOK STORE




HOME PAGE
Triumph Motorcycles
BSA Motorcycles
Norton Motorcycles
Matchless-AJS Motorcycles
AMC-Associated Motor Cycles
Royal Enfield Motorcycles
Ariel Motorcycles
Vincent Motorcycles
Velocette Motorcycles
Rickman Motorcycles
Japanese Motorcycles
Cafe Racers
Choppers & Bobbers
Rat Bikes
Classic Racing Motorcycles
Classic Motorcycle Auctions
Classic Motorcycle Shows
Classic Motorcycle Rides
Classic Motorcycle Restoration
Classic Motorcycle Shops
Classic Motorcycle Clubs
Classic Motorcycle Photo Gallery
Classic Motorcycle Events Calendar
Send us Pictures of YOUR BIKE
YOUR BIKE Pictures
About Us
Site Map
CONTACT US
Brit Iron Back Issues
Visit our STORE
Subscribe to our FREE e-zine & get a FREE 11X17 Poster
BACK TO TOP - 1961 Triumph Bonneville


1961 Triumph Bonneville
1/1/14




CLASSIC TRIUMPHS
2015 Wall Calendar

HISTORIC MOTORCYCLES
2015 Wall Calendar
ULTIMATE MOTORCYCLES
2015 Wall Calendar

Check out all our
MOTORCYCLE CALENDARS