Honda GCV Series Engine Torque Specs

Honda GCV engines power the vast majority of residential push and self-propelled mowers -- including most Honda HRX and HRN mowers -- along with pressure washers and small equipment. These fastener torque specs are pulled directly from Honda's own engine-assembly information sheets and shop manuals, not paraphrased from a parts blog, so the cylinder/head-cover, connecting-rod, and flywheel-nut numbers below match what a Honda service tech would use. Honda redesigned this line partway through -- GCV170/GCV200 are a newer platform than GCV160/GCV190 -- and the two families genuinely use different torque tables, so they are kept separate below rather than merged.

Where these numbers come from: GCV160/GCV190 (and the related GSV190) values come from Honda's official "GCV135 - GCV160 - GCV190 - GSV190 Engine Assembly" information sheet (honda-engines-eu.com, (c) Honda Motor Co. 2009), which states one shared torque table across all four named models rather than splitting per displacement -- so those rows carry high confidence for GCV160 and GCV190 alike. Valve-clearance numbers for that family come from the separate GCV190 shop manual's maintenance-standards table; they are flagged medium confidence when carried over to GCV160 specifically, since that document does not restate them under a "GCV160" heading. GCV170/GCV200 values come from Honda's official shop manual (shop-manual-gcv145-170-200-62z9l20-en.pdf), which prints a full per-fastener torque table (N-m / kgf-m / lbf-ft) naming both engines together -- high confidence throughout. Neither generation has an oil drain-plug bolt (both drain by tilting the engine with the filler cap removed) -- that is a confirmed design fact, not a gap. Both generations DO have a published spark-plug torque of 20 N-m: shop manual 61ZM000 prints it for GCV135/160/190/GSV190 (14 ft-lb) and 62Z9L20 prints it for GCV145/170/200 (which Honda rounds to 15 lbf-ft). An earlier revision of this file recorded the older generation as having no published figure, because the GCV160 owner's manual gives the seat-then-half-turn method instead of a number; the shop manual's torque table settles it. Where the shop manual and the engine-assembly information sheet disagree on the flywheel nut, both figures are recorded on the row and the shop manual is the one published. The optional GCV530/GXV530 V-twin and GC160/GC190 horizontal-shaft siblings were also researched: GCV530/GXV530 has real sourced numbers (see below); GC160/GC190 were originally left out because the shop-manual PDF first located was a scanned "electronic shop manual" export whose in-procedure torque call-out boxes did not survive conversion (they render as empty boxes labeled only "TORQUE"). That limitation applies only to the procedural call-outs: a readable copy of the same manual (61ZL800, June 2007) was located during issue #432 and its SPECIFIC TORQUE VALUES table in the service-information section is a plain table that extracts cleanly, giving cylinder head cover bolt M6x1.0 = 12 N-m, spark plug M14x1.25 = 20 N-m, flywheel nut M14x1.5 = 52 N-m, oil drain plug M12x1.5 = 24 N-m, connecting rod bolt M7x1.0 = 12 N-m. Those figures now back the GC row on PressureWasherTorquePage; GC160/GC190 still have no entry in this dataset and should get a proper one rather than being inferred from the GCV rows below.

Honda GCV160 (160cc)

Fastener torques are from Honda's official "GCV135 - GCV160 - GCV190 - GSV190 Engine Assembly" information sheet, which explicitly names GCV160 in its one shared torque table (the sheet does not print separate numbers per model in this family). Valve clearance is cross-applied from the GCV190 shop manual's maintenance-standards table (same core architecture) and flagged medium confidence for that reason. GCV160 has no oil drain-plug bolt -- oil is drained by tilting the engine with the filler cap/dipstick removed. Honda DOES publish a numeric spark-plug torque for this generation: shop manual 61ZM000 prints 20 N-m (14 ft-lb) for the 14x1.25 plug. The owner's manual gives the seat-then-half-turn method instead, which is the same joint by another route; an earlier reading of this file recorded "no published figure" from the owner's manual alone. Note also that the flywheel-nut figures below come from the assembly sheet and are CONTRADICTED by 61ZM000 -- see the conflict note on those rows.

Component	Torque	Thread	Confidence	Notes
cylinder head cover bolt	9 ft-lb	M6x12mm (4 bolts)	high	12 N-m / 1.2 kgf-m. GCV135/160/190/GSV190 use a bolt-on valve/cam cover rather than true head bolts -- this is the closest equivalent fastener.
connecting rod bolt	9 ft-lb	—	high	12 N-m / 1.2 kgf-m (2 bolts).
flywheel nut (aluminum flywheel)	55 ft-lb	M14x1.5 special nut	high ⚠ sources disagree	75 N-m / 7.5 kg-m, per Honda shop manual 61ZM000 (GCV135/GCV160/GCV190/GSV190) TORQUE VALUES table. CONFLICT: Honda's own "GCV135 - GCV160 - GCV190 - GSV190 Engine Assembly" information sheet gives 52 N-m (38 ft-lb) for the same fastener. Both documents are genuine Honda. The shop-manual figure is published here because it is the service specification and because 52 N-m is also exactly the GC/GS family figure (manual 61ZL800), which makes the assembly sheet's number look like a cross-family carry-over. Under-torquing a flywheel nut is the dangerous direction -- it lets the flywheel slip on its taper and shear the key. Check which flywheel you have and use a flywheel holder, never an impact gun.
flywheel nut (cast iron flywheel)	63 ft-lb	M14x1.5 special nut	high ⚠ sources disagree	75 ~ 85 N-m / 7.5 ~ 8.5 kg-m (55 ~ 63 ft-lb) per Honda shop manual 61ZM000; the table prints a range; 63 ft-lb is the top of it and is the number shown here so this row is distinguishable from the aluminum row, but anywhere in 55-63 ft-lb is within Honda spec. CONFLICT: the Honda "GCV135 - GCV160 - GCV190 - GSV190 Engine Assembly" information sheet gives 74 N-m (54 ft-lb) instead. See the aluminum-flywheel row for why the shop manual is preferred.
spark plug	14 ft-lb	M14x1.25	high	20 N-m / 2.0 kg-m per Honda shop manual 61ZM000 TORQUE VALUES table. An earlier reading of this repo recorded "no published figure" because the owner's manual and the maintenance section give the seat-then-turn method instead (thread in by hand to seat the washer, then 1/2 turn more for a new plug, 1/8-1/4 turn if reused). Both are Honda instructions for the same joint. Plug: Honda splits by application -- BPR6ES on pressure-washer applications, BPR5ES on all others; on ACS-equipped engines Honda warns specifically to fit the BPR5ES and not the cooler BPR6ES. Gap 0.7-0.8 mm (0.028-0.031 in).
engine oil drain plug	Not published	—		N/A -- GCV160 has no drain-plug bolt. Oil is changed by removing the oil filler cap and tilting the engine to drain through the filler neck.
crankcase cover (oil pan) bolt	9 ft-lb	M6x25mm (8 bolts)	high	12 N-m / 1.2 kgf-m. Loosely tighten each bolt, then torque in the numbered 1-8 sequence shown on Honda's diagram.
governor holder shaft bolt	9 ft-lb	M6x14mm (2 bolts)	high	12 N-m / 1.2 kgf-m. Minor internal fastener, included for completeness.
valve clearance (cold), intake	Not published	—		Not a torque spec -- clearance value: 0.15 +/- 0.04 mm. Cross-applied from the GCV190 shop manual's maintenance-standards table (same architecture); not restated under a GCV160-specific heading, so flagged medium rather than high.
valve clearance (cold), exhaust	Not published	—		Not a torque spec -- clearance value: 0.20 +/- 0.04 mm. Cross-applied from the GCV190 shop manual (see intake row note).

Honda GCV190 (187cc)

Fastener torques are from Honda's official "GCV135 - GCV160 - GCV190 - GSV190 Engine Assembly" information sheet, which explicitly names GCV190. Valve clearance and spark-plug gap come from GCV190's own dedicated shop manual (shop-manual-gcv190-en.pdf), which does carry a plain maintenance-standards table even though its procedural "TORQUE" call-out boxes did not survive PDF conversion. Displacement (187cc) is shared with the horizontal-shaft GC190 -- same bore/stroke core engine, though the two families do NOT share a flywheel-nut torque (GC/GS is 52 N-m per 61ZL800; GCV is 75 N-m per 61ZM000). The spark-plug and flywheel rows below are sourced from shop manual 61ZM000; where it disagrees with the assembly sheet the conflict is recorded on the row itself.

Component	Torque	Thread	Confidence	Notes
cylinder head cover bolt	9 ft-lb	M6x12mm (4 flange bolts)	high	12 N-m / 1.2 kgf-m. Confirmed twice: the assembly sheet gives the number, and GCV190's own shop manual independently confirms "the four 6 x 12 mm flange bolts" as the fastener (page 38 of that manual, though its torque box itself is blank).
connecting rod bolt	9 ft-lb	—	high	12 N-m / 1.2 kgf-m (2 bolts).
flywheel nut (aluminum flywheel)	55 ft-lb	M14x1.5 special nut	high ⚠ sources disagree	75 N-m / 7.5 kg-m, per Honda shop manual 61ZM000 (GCV135/GCV160/GCV190/GSV190) TORQUE VALUES table. CONFLICT: Honda's own "GCV135 - GCV160 - GCV190 - GSV190 Engine Assembly" information sheet gives 52 N-m (38 ft-lb) for the same fastener. Both documents are genuine Honda. The shop-manual figure is published here because it is the service specification and because 52 N-m is also exactly the GC/GS family figure (manual 61ZL800), which makes the assembly sheet's number look like a cross-family carry-over. Under-torquing a flywheel nut is the dangerous direction -- it lets the flywheel slip on its taper and shear the key. Check which flywheel you have and use a flywheel holder, never an impact gun.
flywheel nut (cast iron flywheel)	63 ft-lb	M14x1.5 special nut	high ⚠ sources disagree	75 ~ 85 N-m / 7.5 ~ 8.5 kg-m (55 ~ 63 ft-lb) per Honda shop manual 61ZM000; the table prints a range; 63 ft-lb is the top of it and is the number shown here so this row is distinguishable from the aluminum row, but anywhere in 55-63 ft-lb is within Honda spec. CONFLICT: the Honda "GCV135 - GCV160 - GCV190 - GSV190 Engine Assembly" information sheet gives 74 N-m (54 ft-lb) instead. See the aluminum-flywheel row for why the shop manual is preferred.
spark plug	14 ft-lb	M14x1.25	high	20 N-m / 2.0 kg-m per Honda shop manual 61ZM000 TORQUE VALUES table. An earlier reading of this repo recorded "no published figure" because the owner's manual and the maintenance section give the seat-then-turn method instead (thread in by hand to seat the washer, then 1/2 turn more for a new plug, 1/8-1/4 turn if reused). Both are Honda instructions for the same joint. Plug: Honda splits by application -- BPR6ES on pressure-washer applications, BPR5ES on all others; on ACS-equipped engines Honda warns specifically to fit the BPR5ES and not the cooler BPR6ES. Gap 0.7-0.8 mm (0.028-0.031 in).
engine oil drain plug	Not published	—		N/A -- GCV190 has no drain-plug bolt. Shop manual: "Tilt the engine toward the oil filler cap side and drain the used oil into a suitable container."
crankcase cover (oil pan) bolt	9 ft-lb	M6x25mm (8 bolts)	high	12 N-m / 1.2 kgf-m. Numbered 1-8 tightening sequence.
governor holder shaft bolt	9 ft-lb	M6x14mm (2 bolts)	high	12 N-m / 1.2 kgf-m.
valve clearance (cold), intake	Not published	—		Not a torque spec -- clearance value: 0.15 +/- 0.04 mm.
valve clearance (cold), exhaust	Not published	—		Not a torque spec -- clearance value: 0.20 +/- 0.04 mm.

Honda GCV170 (166cc)

GCV170 is the newer redesigned platform (not the same architecture as GCV160) -- all values are from Honda's official shop manual for this specific generation (shop-manual-gcv145-170-200-62z9l20-en.pdf), which prints one shared torque table naming GCV170 and GCV200 together, with full N-m/kgf-m/lbf-ft columns. Bore x stroke 60.0 x 59.0 mm, 166cc.

Component	Torque	Thread	Confidence	Notes
cylinder bolt (head equivalent)	18 ft-lb	M8x1.25 (two 8x40mm + two 8x25mm bolts)	high	24 N-m / 2.4 kgf-m. GCV170/200 use a one-piece cylinder casting with a bolt-on valve cover rather than a separate head -- Honda's own torque table calls this fastener "Cylinder bolt," not "cylinder head bolt."
connecting rod bolt	9 ft-lb	M7x1.0	high	12 N-m / 1.2 kgf-m.
flywheel nut (light flywheel type)	41 ft-lb	M14x1.5	high	55 N-m / 5.5-5.6 kgf-m (Honda's own doc prints 5.6 kgf-m once and 5.5 kgf-m once for the same 55 N-m figure -- a minor internal rounding inconsistency; the N-m and lbf-ft columns agree).
flywheel nut (heavy flywheel type)	55 ft-lb	M14x1.5	high	75 N-m / 7.6 kgf-m.
spark plug	15 ft-lb	M14x1.25	high	20 N-m / 2.0 kgf-m, which Honda rounds to 15 lbf-ft in this manual. The older GCV135/160/190 generation specifies the same 20 N-m in its own shop manual (61ZM000), where Honda rounds it to 14 ft-lb -- the plug torque is one of the few things the two platforms share, so the difference between 14 and 15 here is rounding, not a different spec. Everything else about the two platforms differs; do not cross-apply the rest.
engine oil drain plug	Not published	—		N/A -- no drain-plug bolt is listed in the torque table or the oil-change procedure; oil is changed by tilting the engine and draining through the oil filler neck/dipstick opening, same as GCV160/190.
crankcase cover bolt	18 ft-lb	M8x1.25	high	24 N-m / 2.4 kgf-m.
rocker arm shaft (valve lifter) bolt	7 ft-lb	M6x1.0	high	10 N-m / 1.0 kgf-m. Honda's table lists this as "Valve lifter bolt" -- it retains the rocker arm shaft and is this platform's equivalent to a "rocker arm pivot bolt."
valve adjusting lock nut	5.9 ft-lb	M5x1.0	high	8 N-m / 0.8 kgf-m.
governor arm nut	9 ft-lb	—	high	12 N-m / 1.2 kgf-m. Throttle-governor linkage nut, not a core structural fastener, included because Honda's table lists it.
valve clearance (cold), intake	Not published	—		Not a torque spec -- clearance value: 0.08 - 0.12 mm (0.003 - 0.005 in). Same value for intake and exhaust on this platform (unlike GCV160/190, which differ by valve).
valve clearance (cold), exhaust	Not published	—		Not a torque spec -- clearance value: 0.08 - 0.12 mm (0.003 - 0.005 in). Same as intake on this platform.

Honda GCV200 (201cc)

Same official shop manual as GCV170 above (shop-manual-gcv145-170-200-62z9l20-en.pdf); Honda prints one shared torque table for "GCV170/GCV200" with identical fastener values for both displacements -- only the bore (66.0mm vs 60.0mm), sleeve/piston dimensions, and governed-speed specs differ between the two engines. Bore x stroke 66.0 x 59.0 mm, 201cc.

Component	Torque	Thread	Confidence	Notes
cylinder bolt (head equivalent)	18 ft-lb	M8x1.25 (two 8x40mm + two 8x25mm bolts)	high	24 N-m / 2.4 kgf-m. Identical figure to GCV170 -- Honda's table does not split this value by displacement.
connecting rod bolt	9 ft-lb	M7x1.0	high	12 N-m / 1.2 kgf-m.
flywheel nut (light flywheel type)	41 ft-lb	M14x1.5	high	55 N-m / 5.5-5.6 kgf-m.
flywheel nut (heavy flywheel type)	55 ft-lb	M14x1.5	high	75 N-m / 7.6 kgf-m.
spark plug	15 ft-lb	M14x1.25	high	20 N-m / 2.0 kgf-m.
engine oil drain plug	Not published	—		N/A -- no drain-plug bolt; oil is changed by tilting the engine and draining through the oil filler neck.
crankcase cover bolt	18 ft-lb	M8x1.25	high	24 N-m / 2.4 kgf-m.
rocker arm shaft (valve lifter) bolt	7 ft-lb	M6x1.0	high	10 N-m / 1.0 kgf-m.
valve adjusting lock nut	5.9 ft-lb	M5x1.0	high	8 N-m / 0.8 kgf-m.
valve clearance (cold), intake	Not published	—		Not a torque spec -- clearance value: 0.08 - 0.12 mm (0.003 - 0.005 in).
valve clearance (cold), exhaust	Not published	—		Not a torque spec -- clearance value: 0.08 - 0.12 mm (0.003 - 0.005 in).

Honda GSV190 (187cc)

GSV190 is a higher-output governor variant of the same GCV190 core engine (construction/pump/commercial equipment rather than mowers), documented on the identical "GCV135 - GCV160 - GCV190 - GSV190 Engine Assembly" sheet, which names GSV190 explicitly in its title. Included as a bonus entry since it shares the exact same shared torque table as GCV160/GCV190 above -- including the flywheel-nut figures, which come from shop manual 61ZM000 (75 N-m aluminum, 75~85 N-m cast iron) and are contradicted by the assembly sheet. See the conflict notes on those rows.

Component	Torque	Thread	Confidence	Notes
cylinder head cover bolt	9 ft-lb	M6x12mm (4 bolts)	high	12 N-m / 1.2 kgf-m.
connecting rod bolt	9 ft-lb	—	high	12 N-m / 1.2 kgf-m (2 bolts).
flywheel nut (aluminum flywheel)	55 ft-lb	M14x1.5 special nut	high ⚠ sources disagree	75 N-m / 7.5 kg-m, per Honda shop manual 61ZM000, whose title covers GSV190 alongside GCV135/160/190. CONFLICT: the "GCV135 - GCV160 - GCV190 - GSV190 Engine Assembly" information sheet gives 52 N-m (38 ft-lb) for the same fastener. Both documents are genuine Honda. The shop manual is followed because it is the service specification and because 52 N-m is exactly the GC/GS family figure from manual 61ZL800, i.e. very likely a cross-family carry-over. Under-torque is the dangerous direction on a flywheel taper -- it lets the flywheel slip and shear its key.
flywheel nut (cast iron flywheel)	63 ft-lb	M14x1.5 special nut	high ⚠ sources disagree	61ZM000 prints a RANGE for the cast-iron flywheel: 75~85 N-m (7.5~8.5 kg-m, 55~63 ft-lb). 63 ft-lb is the top of that range and is shown here so this row is distinguishable from the aluminum row; anywhere in 55-63 ft-lb is within Honda spec. CONFLICT: the engine-assembly information sheet gives 74 N-m (54 ft-lb) instead -- see the aluminum-flywheel row for why the shop manual is preferred.
crankcase cover (oil pan) bolt	9 ft-lb	M6x25mm (8 bolts)	high	12 N-m / 1.2 kgf-m.

Honda GCV530 (V-Twin)

Optional/bonus entry -- larger commercial V-twin, shares its shop manual and assembly sheet with the GXV530. Sourced from Honda's official "GCV530 - GXV530 Engine Assembly Information" sheet. This is a structurally different engine from the GCV160-200 singles above: it has 4 connecting-rod bolts (2 cylinders), 8 cylinder-retaining flange nuts, and -- unlike every single-cylinder GCV above -- a genuine 20mm crankcase oil-drain bolt on equipped models.

Component	Torque	Thread	Confidence	Notes
cylinder-to-crankcase flange nut (head equivalent)	24 ft-lb	8mm flange nut (8 total, 4 per cylinder)	high	32 N-m / 3.3 kgf-m.
connecting rod bolt	9 ft-lb	—	high	12 N-m / 1.2 kgf-m (4 bolts total, 2 per connecting-rod cap).
flywheel/starter-pulley bolt	116 ft-lb	16mm	high	157 N-m / 16.0 kgf-m. The V-twin uses a large central through-bolt rather than the single-cylinder GCV's 14mm nut -- do not confuse this with the 41-63 ft-lb GCV160-200 flywheel-nut figures.
oil drain bolt (equipped type only)	33 ft-lb	20mm	high	44 N-m / 4.5 kgf-m. Unlike the single-cylinder GCV160-200, GCV530/GXV530 does have a dedicated crankcase drain bolt on equipped models.
crankcase cover (oil pan) bolt	17 ft-lb	M8x40mm (7 bolts)	high	24 N-m / 2.4 kgf-m. Loosely tighten, then torque in the numbered sequence.
valve adjusting lock nut	5.4 ft-lb	—	high	7.5 N-m / 0.75 kgf-m (4 nuts total, 2 per cylinder). Genuinely lower than the single-cylinder GCV170/200's 8 N-m figure -- not a typo, a different published spec for this engine.
oil filter (equipped type only)	9 ft-lb	—	high	12 N-m / 1.2 kgf-m, per Honda's torque-wrench spec for filter installation (not a hand-tighten-only spec on this engine).
cylinder head cover bolt	Not published	6x12mm (8 bolts shown on diagram)		GAP: the diagram shows "6 x 12 (8)" head-cover bolts but no torque figure was legible adjacent to that callout in Honda's document -- do not assume it matches the single-cylinder GCV's 12 N-m figure.
spark plug	Not published	—		GAP: plug type given (BPR5ES NGK / W16EPR-U Denso) but no numeric install torque found in this document.

What is the head/cylinder-cover bolt torque on a Honda GCV160 lawn mower engine?

12 N·m (9 ft-lb) on the M6x12mm valve-cover bolts, per Honda's official GCV135/160/190/GSV190 engine-assembly sheet. Note this is a different, newer-generation engine than the GCV170/200 (see below) -- do not mix up the two tables.

What is the head bolt torque on a Honda GCV170 or GCV200 (found in many HRX/HRN mowers)?

24 N·m (18 ft-lb) on the "cylinder bolts" (two 8x40mm + two 8x25mm, M8x1.25), per Honda's official GCV145/170/200 shop manual. GCV170 and GCV200 share the exact same torque table despite the different bore size.

How do I drain the oil on a Honda GCV mower engine -- where is the drain plug?

There isn't one. Every GCV160/170/190/200 engine drains through the oil filler neck: remove the filler cap/dipstick and tilt the engine so oil pours out that opening. This is confirmed directly in Honda's owner's and shop manuals for both the older (160/190) and newer (170/200) generations -- if you're searching for a drain bolt torque spec, it doesn't exist because the part doesn't exist on these engines.

What torque do I use to install a spark plug in a Honda GCV mower engine?

Honda's GCV shop manual (61ZM000) specifies 20 N·m — 14 ft-lb — for the 14x1.25 plug on the GCV135/160/190 and GSV190. The owner's manual gives an equivalent method instead: seat the washer finger-tight, then 1/2 turn more for a new plug (1/8-1/4 turn if reusing one). GCV170/200 is a different platform and Honda publishes 20 N·m there too, which it rounds to 15 ft-lb.

What is the flywheel nut torque on a Honda GCV mower engine?

GCV135/160/190/GSV190: 75 N·m (55 ft-lb) for an aluminum flywheel, 75-85 N·m (55-63 ft-lb) for cast iron, per shop manual 61ZM000. Honda's engine-assembly information sheet prints lower figures for the same fastener (52 N·m / 74 N·m); where the two disagree this site follows the shop manual, and 52 N·m is in any case the GC/GS family's figure rather than the GCV's. GCV170/200: 55 N·m (41 ft-lb) light flywheel, 75 N·m (55 ft-lb) heavy flywheel. Always use a flywheel-holding tool, never an impact gun.

Are GCV160 and GCV170 the same engine with different torque specs, or completely different designs?

Different designs, not just different numbers. GCV170/GCV200 are Honda's newer redesign of this displacement class -- different cylinder/head architecture (a one-piece "cylinder bolt" cover rather than a separate valve cover, and real M8 cylinder bolts where the GCV160/190 has none at all), a different flywheel-nut spec, and its own dedicated shop manual. The spark plug happens to land on the same 20 N·m in both generations, but that is a coincidence of plug size rather than a shared spec. Don't cross-apply GCV160/190 numbers to a GCV170/200, or vice versa.

Related lookups

Loading interactive lookup…