Description

Honda CB250, 350, CL250, SL350 1971 Workshop Manual

If you’ve ever tried to reassemble a 1971 Honda twin using a greasy photocopy from the internet, you know the feeling of finding a bolt left over or a valve clearance that sounds like a maraca. That’s because aftermarket manuals skip steps or print wrong numbers. This is the real thing – the 1971 Honda CB250, 350, CL250, SL350 Workshop Manual, published by Honda Motor Co., Ltd. in Japan. 359 pages, factory-original scans, not a reprint of a reprint. Every spec came off the assembly line. I’ve torqued more head bolts than most guys have had hot dinners, and I won’t touch a 350 without this book on the bench.

Engine Overhaul: Valve Clearance and Torque Specs

The engine section (starting page 29) is laid out like a tech’s workbench – disassembly, inspection, reassembly, all separated so you don’t skip the inspection step. The Valve Mechanism (section 4.5) covers shim selection, cam chain timing marks, and the exact feeler gauge gap for intake and exhaust. Page 31 shows the head bolt torque sequence. Use a beam or click-type torque wrench, not the old “uugh” method. Special tools are listed in section 2 (page 15) – you’ll need a valve spring compressor and a flywheel puller for the SL350. Don’t fake it with a screwdriver; you’ll bend a stem.

4.5 Valve Mechanism – What the Factory Manual Tells You

Most people rush through valve adjustment and end up with burnt seats. The manual breaks it down: Description (how the rocker arm and cam work), Disassembly (removing the cylinder head with the engine in the frame), Inspection (look for pitting on the cam lobes, measure tappet clearance cold), then Reassembly with torque values in ft-lb. Critical note: the workshop manual specifies special tool number 07916-3000000 for compressing the valve springs. If you don’t have it, order one before you start. Section 4.5.D includes the reassembly order and a note about lubricating the valve stems with engine oil – not assembly lube, not WD-40. Oil.

Transmission Overhaul – Why Aftermarket Schematics Fail

I’ve seen three different “compatible” transmission diagrams for the CB250, all wrong. This manual uses the original Honda drawings for the gearshift mechanism (4.12), kick starter (4.13), and the main transmission shafts (4.11). The inspection section on page 54 tells you how to measure shift fork thickness and drum groove depth. Aftermarket manuals usually skip the inspection tolerances – you end up with a gearbox that pops out of second. The factory spec is 0.05–0.15 mm clearance on the shift fork groove. Page 55 gives the reassembly sequence for the transmission, including the circlip orientation that everyone misses. Do it right the first time. If you need a broader overview of manual transmission design, Manual Transmission covers the basics, but the Honda-specific tolerances are only in this manual.

Does This Manual Cover the Frame and Suspension?

Yes. Section 5 (Frame) runs from page 61 to 100, covering handlebar, fork top bridge, front cushion (twin-tube shock absorber), steering stem, fuel tank, frame body, seat, stand and brake pedal, exhaust pipes, air cleaners, rear fork, rear cushion (De Carbon type shown on page 80), and both front and rear wheels. The disc brake system gets its own subsection starting on page 87 – caliper disassembly, master cylinder inspection, and disc adjustment. Most suspension rebuilds fail because the assembly order is wrong. The manual lists every step for the front cushion, including oil volume and viscosity. For the rear shock, it explains the De Carbon gas-charged unit separately from the twin-tube valve type. That distinction alone keeps your ride from bottoming out.

Electrical and Ignition Diagnostics

A short paragraph is all it takes: ignition coil testing is in section 6.1, page 101. Primary resistance, secondary resistance, spark plug gap – all specified. Don’t assume a used coil is good because it sparks. Measure it.

Source Validity – OEM Factory Documentation

This is a direct scan of the original 1971 shop manual printed by Honda. No aftermarket translation, no “compatible with” disclaimers. Every page matches what a Honda dealer tech would have used. The table of contents lists seven chapters: Technical Data, Special Tool, Minor Model Change Table, Engine, Frame, Electrical Parts, and an appendix of principal modifications. The wiring diagrams are factory schematics, not re-drawn. If you want additional factory resources for later years, the Honda CB250 CB400N 1978-1984 Workshop Manual covers the twin-carb models, and the Honda CB250, CL250, CB350, CL350 Workshop Manual – OEM Factory Specs extends coverage to the scrambler variants. For the 1975 updates, see the Honda CB250, 360, CL360, CJ250T, CJ360T 1975 Workshop Manual – OEM Specs.

Does this manual cover the CB350 twin?

Yes, all models listed: CB250, CB350, CL250, CL350, SL350. The technical data chapter applies to each variant.

Are the torque specs listed for every engine fastener?

Yes. Section 1 (Technical Data) gives cylinder head nut torque (24–26 ft-lb), connecting rod nut (14–16 ft-lb), and many others. The manual also includes tightening sequences, like the four-step pattern for the cylinder head on page 31. If you follow those numbers and sequences, you won’t strip threads or warp the head. I’ve seen too many homebuilds lose compression because they skipped the sequence. The manual also lists bolt sizes and thread pitches for each fastener, so you know exactly what wrench to grab. No guessing.

If you’re about to dig into a 1971 Honda twin, stop hunting for forum threads and blurry PDFs. The factory numbers are here, laid out the way Honda intended. Get the documentation that keeps your engine together and your bike safe. Access the Factory Manual and put real specs on your workbench.