Honda SL350: history, specs, pictures

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Honda SL350
Also called SL 350
Production 1969
Class Enduro
Successor Honda XL350
325cc 4-stroke OHC parallel twin
Bore / Stroke 63.5mm x 63.5mm
Compression ratio 9.5:1
Top Speed 86.04 mph
1/4 mile 15.95 seconds @ 78.39 mph
0-60 8.6 seconds
Horsepower 32.99 HP (24.6 KW) @ 9500RPM
Fuel System 2x Kehin 24mm Carburettor
Spark Plug NGK B8ES[1]
Battery YUASA 12N12A-4A-1 '69-70
YUASA 12N5-4B '71-73[1]
Final Drive Chain: 520x100
Front Sprocket 16T
Rear Sprocket 40T
Brakes Front: Drum
Rear: Drum
Front Tire 3.50-19
Rear Tire 4.00-18
Recommended Oil Honda GN4 10W-40
Related Honda CL350
Honda CB350K
Manuals File:Honda CL350 SL350 CB350 Factory Service Manual.pdf
More Manuals

Brochures ·

The Honda SL 350 was a 325cc 4-stroke OHC parallel twin motorcycle produced by Honda in 1969.

History[edit | edit source]

The motor in the electric start first effort ko model , was EXACTLY the same as the CB350 & CL350 models, same camshaft, same crankshaft, ignition, gearbox, etc. The only difference was the final drive gearing, and exhaust systems. The easiest way to tell from a distance or a partially disassembled sl350 is the electric start and single downtube on the ko model the ko model was just a dressed up cb the kickstart only double cradle frame sl350 was really a huge improvement mainly because of the lighter wheels and over 60lbs lighter weight

From 1972 SL’s had standard Kehin 24mm carbs that eliminated the aforementioned CV’s slide issues, a very mild cam profile with less lift less duration and no overlap. Also, the kick start only models had smaller intake ports to suit the 24mm carbs and with a more restrictive exhaust system, brought the SL’s power down to 30 horsepower, from the CB’s 36 horsepower at 9000 rpm, and the CL’s 34 at 10,000 rpm. Same size 34mm/28mm valves were used. the sl350ko had the same 180mm front hub while the k1 had 160mm hub from the cb175 with a 19 wheel k1-on had 21 front wheel 35mm forks and slightly different steering geometry rear wheels k1-on were smaller lighter hubs than sl350ko/cb350/cl350 rear hubs another major difference in the k1-on kickstart only sl350 was the entirely different but lighter double cradle frame, the advent of primary kickstarting meaning you can kickstart in gear with the clutch disengaged the se sl's also had simply straight cut primary drive gears with no noise reducing paired gear lashup nothing in the gearbox is the same as the electric start 350 twins nothing in the gearbox will interchange nor will the crankcases clutch cover case alternator case/cover or crankshaft the sl350 kickstart only crankshaft has a shorter stub shaft on the left end that will not allow the electric start one way clutch countershaft sprocket cover clutch release mechanism and clutch plates will interchange with electric start 350 twins

And what a motor it was. The 350 Honda twin was anvil reliable, with over 300,000 copies being sold in the USA alone, it was one of the most popular motorcycles ever produced. When the SL350 got some knobbies strapped to it, and decent shocks bolted on the back, the bike became an unstoppable woods weapon, as nothing short of an atomic blast would cease the rear wheel from spinning. It was also, in my mind one of the best looking vertical twin cylinder motors ever produced, right up there with a Triumph or BSA in the looks department.

In 1974 the SL350 was replaced by the XL350, with the CB & CL being replaced by the 360 twin, a relative failure when compared to the 350. And you can still find a nice example of the 350 twin for cheap, since the 350 is still not recognized as a true “classic”.

Engine[edit | edit source]

A 63.5mm bore x 50.60mm stroke result in a displacement of just 326.0 cubic centimeters.

Chassis[edit | edit source]

It came with a 3.50-19 front tire and a 4.00-18 rear tire. Stopping was achieved via Drum in the front and a Drum in the rear.

1969 - 1973 Honda SL 350[edit | edit source]

The Honda SL350 has a standard Honda 350 twin cylinder, four-stroke engine with a modified cam for increased low-end torque and 33 horsepower at 9500rpm.

1969-1970[edit | edit source]

The Honda Motosport 350 designated SL350K0 was sold in 1969-70. Three colors were available: Candy Sapphire Blue, Candy Ruby Red, and Candy Gold. The fuel tank stripe was white. The frame had a single downtube. It had both a electric and kick starter. The engine was a 325cc 4-stroke OHC parallel twin with two CV carburetors. The transmission was a 5-speed. The front wheel was 19" and the rear wheel was 18". The serial number began SL350-1000001.

1970-1971[edit | edit source]

The SL350K1 Motosport 350 was sold from 1970 to 1971 in one of three colors: Candy Ruby Red, Candy Sapphire Blue, or Candy Topaz Orange. The gas tank stripe was white. It now had a double downtube frame. The electric start was deleted. The engine was a 325cc 4-stroke OHC parallel twin with two piston valve carburetors. The serial number began SL350-2000001.

1972-1973[edit | edit source]

The SL350K2 was sold from 1972 to 1973 in two available colors: Candy Panther Gold with Yellow or Marina Blue Metallic with Yellow. The gas tank panel was yellow. The "350" side cover decal was also yellow. the fenders were unpainted aluminum. The front wheel increased to 21" while the rear decreased an inch to 18". The engine was a 325cc 4-stroke OHC parallel twin with two piston valve carburetors. The serial number began SL350-3000001.

In Media[edit | edit source]

References[edit | edit source]

  1. 1.0 1.1 2019 Western Power Sports Catalog. Western Power Sports. 2019. 

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