Engine (1520cc Flat-Six)¶
The heart of the 2000 Honda GL1500 SE Gold Wing is a 1,520 cc liquid-cooled, horizontally-opposed (boxer) flat-six, SOHC with two valves per cylinder and hydraulic lash adjusters (no routine valve clearance adjustment). It breathes through two 36 mm Keihin CV carburetors feeding all six cylinders — the GL1500 is carbureted, not fuel-injected (electronic fuel injection arrived with the GL1800 in 2001). The 2000 model year was the final year of the GL1500 generation (1988–2000), sporting chrome valve covers and 25th-Anniversary trim. This file covers engine internals, the timing-belt system (a critical maintenance item), and the lubrication system.
Units are given in both metric and imperial throughout. Torque values are cross-referenced in Torque Specifications; service intervals in the Maintenance Schedule. See also Cooling System, Fuel System & Carburetors, and Transmission & Electric Reverse.
1. Engine Overview & Layout¶
| Attribute | Specification |
|---|---|
| Type | Four-stroke, liquid-cooled, horizontally-opposed (flat / boxer) six-cylinder |
| Valvetrain | SOHC (single overhead cam per bank), belt-driven, 2 valves per cylinder |
| Valve adjustment | Hydraulic lash adjusters — no manual clearance adjustment required |
| Displacement | 1,520 cc (92.7–92.8 cu in) |
| Bore × stroke | 71 × 64 mm (2.8 × 2.5 in) — slightly undersquare (long-stroke) |
| Compression ratio | 9.8 : 1 |
| Cooling | Liquid (pressurized, with on-bike radiator + fans) — see Cooling System |
| Induction | 2 × 36 mm Keihin CV (constant-velocity) carburetors — see Fuel System |
| Lubrication | Wet sump, gear-type oil pump, with engine oil cooler |
| Starting | Electric only |
| Max power | ≈73 kW (100 hp / 101 PS) @ 5,200 rpm |
| Max torque | ≈150 N·m (111 lb·ft) @ 4,000 rpm ⚠️ Wikipedia cites 110 lb·ft; ~150 N·m / ~111 lb·ft is the most common figure — confirm against factory data |
| Idle speed | 800 ± 80 rpm |
| Firing order | 1–4–5–2–3–6 ⚠️ see cylinder-numbering note below |
| Engine layout benefit | Inherent primary + secondary balance; flat-six is exceptionally smooth |
Why a flat-six? A 60° or inline six can be smooth, but the horizontally-opposed six is in essentially perfect primary and secondary balance — the three cylinders on each bank offset each other. Combined with the low, central mounting of the engine in the frame, this gives the Gold Wing its hallmark turbine-like smoothness and a very low center of gravity for a 360+ kg machine. The flat-six replaced the GL1000/1100/1200 flat-four when the GL1500 launched in 1988.
2. Cylinder Numbering & Firing Order¶
Honda numbers the GL1500's cylinders by bank. The exact convention should be confirmed against the factory service manual, but the widely-reported scheme and firing order are:
| Item | Value |
|---|---|
| Cylinder banks | Left bank and right bank, three cylinders each |
| Numbering convention | Front-to-rear within each bank; #1 is the front cylinder ⚠️ confirm L/R assignment in the service manual |
| Firing order | 1 – 4 – 5 – 2 – 3 – 6 |
| Crankshaft | Opposed pairs share crank throws; even firing intervals give the smooth, even load that is one reason the cam belts are so long-lived |
⚠️ The firing order 1-4-5-2-3-6 is consistently reported by GL1500 owners and forums, but the cylinder-to-position mapping (which physical cylinder is "1") and the left/right bank labeling should be verified against the factory service manual before doing ignition or compression-trace diagnostics.
3. Engine Internals¶
Crankcase, Crankshaft, Pistons, Rings, Bearings¶
| Component | Notes |
|---|---|
| Crankcase | Horizontally-split aluminum case; the two halves clamp the crankshaft main bearings |
| Crankshaft | Forged, running in plain (shell) main bearings; opposed-cylinder pairs share throws |
| Main / rod bearings | Plain insert (shell) bearings, pressure-fed; selected by color-coded size grades ⚠️ specific clearances/grades not verified here — see service manual |
| Connecting rods | Plain big-end bearings on shared crank pins (opposed rods on a common throw) |
| Pistons | Aluminum-alloy; 71 mm bore |
| Piston rings | Typically 2 compression + 1 oil-control ring per piston ⚠️ ring end-gap / wear service limits not verified — confirm in service manual |
| Cylinders | Cast into the crankcase / cylinder blocks; liquid-cooled |
⚠️ Internal clearances, bearing-selection charts, ring end gaps, piston-to-bore clearance, and crankshaft runout service limits were not publicly verifiable during research. These are needed only for a full rebuild and must be taken from the factory Honda service manual (Section: Crankshaft/Transmission and Cylinder Head/Valves). Do not guess these values.
Cylinder Head & Valvetrain¶
| Component | Notes |
|---|---|
| Configuration | SOHC, one camshaft per bank, 2 valves/cylinder |
| Cam drive | Toothed timing belt per bank (two belts total) — see §4 |
| Valve actuation | Rocker arms with hydraulic lash adjusters maintaining zero lash |
| Valve clearance | No manual adjustment — the hydraulic adjusters self-compensate |
Hydraulic lash adjuster (HLA) notes for the DIYer: - The HLAs maintain zero lash between cam lobe and valve while the valve is closed, so the GL1500 valvetrain is famously quiet and needs no periodic valve adjustment. - A failing/worn adjuster won't hold pressure in its high-pressure chamber and must be replaced (not adjusted). Symptom: persistent ticking, often worst on a cold start and slow to quiet down, or that never quiets. - Sticky/sludged adjusters from old oil or short trips can cause ticking; fresh oil of the correct grade and an Italian tune-up sometimes frees them. Severe cases require disassembly. - The only "shims" present are 1 mm ring shims under the cam-holder cap bolts that set adjuster depth in the cam holder — not a clearance adjustment in the conventional sense. ⚠️ Confirm service-limit dimensions in the factory manual before measuring (a service limit around 0.12 in / ~3 mm of adjuster travel is cited by owners but should be verified).
4. Timing Belts (Critical Maintenance Item)¶
Unlike the chain-driven GL1800, the GL1500 uses two toothed rubber timing belts (one per cylinder bank) to drive the camshafts off the crankshaft. This is an interference engine — if a belt breaks or jumps teeth, valves and pistons can collide and cause major, expensive engine damage. Belt service is therefore the single most important scheduled engine job on this bike.
Timing belt facts¶
| Item | Specification |
|---|---|
| Number of belts | 2 (one per bank) |
| Belt type | Toothed rubber timing belt; same tensioner design as GL1200 |
| Honda OEM belt P/N | 14400-371-004 / 14400-371-014 ⚠️ verify current supersession with a Honda dealer / parts catalog |
| Aftermarket equivalents | Gates T274, NAPA 250274, Goodyear Gatorback 40274 (commonly cited) — some sources list Gates T275 / NAPA 250275 / Goodyear 40275; ⚠️ confirm exact tooth count/length for your VIN before buying |
| Tensioner | Spring-loaded, two per engine; OEM tensioner ~$60–100 each, or rebuildable |
| Tensioner adjuster P/N | 14510-MG9-008 (shared GL1200/GL1500/Valkyrie) ⚠️ verify |
| Engine type | Interference — belt failure can destroy the engine |
Replacement interval — read carefully¶
There is real disagreement between the factory schedule and prevailing owner practice:
- Honda's published schedule: inspect the belts at very high mileage — commonly cited as 100,000 mi (160,000 km). Honda's maintenance schedule does not list a short hard-replacement interval, partly because the even firing/loading of the flat-six is gentle on belts.
- Belt-industry guidance (Gates): replace at the recommended interval or every 72 months (6 years), whichever comes first — because rubber ages regardless of miles.
- Owner / community consensus: replace roughly every 50,000–60,000 mi (80,000–95,000 km) or every 5–6 years, more conservatively in cold climates (cold makes old belts brittle; teeth can shear on a cold-start). A 10-year/100k figure is the most lenient commonly seen.
⚠️ Practical recommendation: If the belt history is unknown, replace both belts (and inspect/refresh the tensioners) now. It is cheap insurance against a catastrophic interference failure. Always replace both belts together. See Maintenance Schedule.
Replacement procedure (overview — DIY)¶
This is a moderately involved job (several hours; a lot of plastic/cowl removal), but mechanically straightforward and very rewarding to DIY:
- Engine must be DEAD COLD before setting timing.
- Remove lower cowls, fairing covers, and inner covers to reach the front of the engine. Drain coolant; disconnect radiator hoses as required and the oil-pressure switch wiring; remove the timing-belt covers. (See Cooling System for coolant drain/refill.)
- Set the crankshaft and camshaft timing marks — verify all alignment marks (crank pulley + both cam pulleys) before removing belts. Mark belt direction if reusing (don't — replace).
- Loosen the two bolts on each tensioner (about a half-turn once they break free) and relieve tension; remove old belts.
- Fit new belts with marks aligned. The tensioner springs are often too weak to fully take up slack on new belts — give the tensioner a gentle nudge toward the belt to snug it, then tighten.
- Set deflection: aim for 5–7 mm (≈0.2–0.28 in) of play on the long (free) side of each belt opposite the tensioner. One factory-style check: apply ~4.4 lb (≈2 kg / ~20 N) to a hook over the belt and look for ~5 mm deflection. Don't over-tension (damages tensioner bearings) or under-tension (belt slaps the covers).
- Rotate the engine several full turns by hand and re-verify every timing mark realigns. Recheck deflection.
- Reassemble covers, refill/bleed coolant, reconnect wiring.
Cautions: - Never rotate the engine with a belt removed/loose unless you know the pistons are clear — interference engine. - Replace tensioner springs while you're in there if the bike is high-mileage; consider a tensioner rebuild (~$20 in parts) or new OEM tensioners. - Confirm the belt part number matches your VIN — there are similar-but-different Gold Wing belts.
5. Lubrication System¶
| Item | Specification |
|---|---|
| System | Wet sump, pressure-fed; gear-type oil pump |
| Oil pump | Driven off the crankshaft; the GL1500 is reported to use a scavenge pump (rear) plus a pressure pump (front) — failure of either is serious ⚠️ confirm pump arrangement/pressure spec in the service manual |
| Oil cooler | Yes — the GL1500 has an engine oil cooler (with an anti-vibration mounting grommet, P/N 15604-MG7-000). ⚠️ Confirm whether it is a discrete cooler or integrated with the cooling circuit on your bike |
| Oil filter | Spin-on cartridge — Honda P/N 15410-MFJ-D01 (current part; supersedes earlier 15410-MM9-... type). Cross-refs include Fram PH6017A-type, K&N KN-204-type ⚠️ verify fitment |
| Oil pressure | Pressure switch/idiot light fitted (no factory gauge). ⚠️ Exact oil-pressure spec (kPa/psi at rpm) not verified — see service manual |
Oil capacity¶
| Service | Capacity |
|---|---|
| After draining (oil change, no filter) | 3.5 L (3.1 Imp qt / 3.7 US qt) |
| After oil and filter change | ≈3.7 L (≈3.9 US qt) ⚠️ Owner's manual lists 3.5 L "after draining"; add ~0.2 L for the filter. Many owners simply fill to ~3.7–4.0 US qt and verify on the sight glass / dipstick |
| After complete engine disassembly | Larger (full system) — ⚠️ value not verified; consult service manual |
Always set the final level by the sight glass / dipstick, not by the bottle count. Run the engine briefly, let it settle, and check on level ground.
Recommended oil¶
| Property | Specification |
|---|---|
| Viscosity (factory) | SAE 10W-40 (factory primary recommendation; 10W-30 also acceptable per Honda for flat-four/six). Owners in hot climates often use 15W-40 / 15W-50 |
| API service grade (factory) | SE, SF, or SG "high-detergent quality motor oil" (these older API grades are largely superseded; a modern SL/SM/SN motorcycle-rated oil is fine) |
| Critical: | Use a motorcycle-rated oil with NO friction modifiers / NOT "energy/resource conserving." The GL1500 has a wet clutch sharing the engine oil — friction-modified automotive "energy conserving" oils can cause clutch slip. JASO MA / MA2 rated oil is the safe choice. |
| Final drive | The final drive uses separate hypoid gear oil — do not confuse with engine oil. See Final Drive & Driveshaft. |
Oil & filter change tips¶
- Warm the engine first (a few minutes) so the oil drains better; then let it cool enough to avoid burns.
- Drain bolt is at the bottom of the crankcase; replace/inspect the sealing washer (crush washer) each time.
- Pre-fill the new filter where orientation allows and lightly oil the filter gasket.
- Torque values (see §7 and Torque Specifications): drain bolt 35 N·m (25 ft·lb), filter cartridge 10 N·m (7 ft·lb / ~88 in·lb).
- Replace spark plugs at oil/filter service intervals where due (see Ignition / Maintenance Schedule).
6. Crankcase Breather / PCV (Emission Control)¶
The GL1500 uses a crankcase emission control system: blow-by gases are routed from the crankcase through the air cleaner and back into the combustion chambers (closed PCV-type system). Condensed vapors (mostly water plus some oily mist and unburned fuel) collect in a crankcase breather storage tank with clear drain tube(s).
- Drain the breather tank periodically — whenever you see fluid in the clear tube, and especially after riding in rain or at sustained high rpm/full throttle (it fills faster in wet/humid conditions). Many owners drain it every couple of months.
- There are drain hoses routed down near the alternator; they are normally plugged and opened only to drain.
- Cleaning the breather is on the factory maintenance schedule at each major service interval. See Maintenance Schedule.
- A neglected, overfull breather can push oily condensate into the intake and cause rough running / fouling.
The GL1500 also has a secondary air supply system (pulse air to the exhaust ports for emissions) — inspected per the maintenance schedule; covered under Fuel System & Emissions.
7. Engine Torque Specifications¶
Verified factory values where available; the remainder must come from the service manual. Cross-reference Torque Specifications.
| Fastener | Torque | Source confidence |
|---|---|---|
| Spark plug | 12 N·m (1.2 kgf·m / 9 ft·lb) | Service manual ✓ |
| Cylinder head bolt (9 mm) | 45 N·m (4.5 kgf·m / 33 ft·lb) | Service manual ✓ — follow the manual's sequence (inner/larger bolts first, diagonal pattern) |
| Engine oil drain bolt | 35 N·m (3.5 kgf·m / 25 ft·lb) | Service manual ✓ |
| Oil filter cartridge | 10 N·m (1.0 kgf·m / 7 ft·lb) | Service manual ✓ |
| Camshaft holder bolts | ⚠️ not verified for GL1500 (GL1000 was ~24–28 N·m / 18–21 ft·lb — do not assume identical) | Verify in manual |
| Connecting rod cap nuts | ⚠️ not verified | Verify in manual |
| Crankcase / main bearing bolts | ⚠️ not verified | Verify in manual |
| Flywheel bolt | ⚠️ not verified | Verify in manual |
| Timing belt tensioner bolts | ⚠️ not verified (snug per procedure; loosen ~½ turn to adjust) | Verify in manual |
| Clutch fasteners | ⚠️ not verified | See Clutch / manual |
⚠️ Never guess engine torque values. The four checkmarked values above are corroborated from the GL1500 service manual; everything marked ⚠️ should be taken from the factory manual's "Engine Torque Values" page (around p.21) before assembly. Tighten multi-bolt joints in the manual's specified sequence.
8. Common Engine Problems & DIY Notes¶
- Timing belt age/failure — the #1 thing to address. Wear item, interference engine; replace on time, in pairs. See §4.
- Starter sprag (one-way) clutch sludging — that engine area gets poor oil flow; sludge can keep the sprags from engaging. Symptom: hit the starter, starter spins but engine doesn't crank. A common home fix is to add a solvent (e.g. ~½ can Sea Foam) to warm oil and ride gently for an hour to dissolve the sludge; repeat if needed. Persistent cases need teardown. Keep oil fresh and avoid chronic short trips.
- Water pump weep-hole leak — coolant (or oil) from the weep hole signals a failing pump seal. The correct fix is to replace the water pump; do not plug/epoxy the weep hole. See Cooling System.
- Ticking valvetrain — usually a hydraulic lash adjuster not pumping up (oil grade/level, sludge, or a worn adjuster). Try correct fresh oil first; replace adjuster(s) if it persists.
- Charging/stator — heavy electrical loads (audio, CB, lights on the SE) stress the alternator; some owners fit higher-output "poor boy" alternator conversions. (Electrical detail belongs in Charging & Electrical.)
- Off-idle hesitation (1988–1989 only) — addressed by a factory recall on early bikes; not applicable to a 2000 SE, but worth knowing the generation's history. Check NHTSA recalls.
- Oil-leak housekeeping — confirm the breather tank is drained (oily residue at the intake often traces to a neglected breather rather than a true leak).
Sources¶
- motorcyclespecs.co.za — Honda GLX 1500 SE specifications: https://www.motorcyclespecs.co.za/model/Honda/honda_glx_1500_se_91.html
- autoevolution — HONDA GL1500 Gold Wing SE (1999–2000) specs: https://www.autoevolution.com/moto/honda-gl1500-gold-wing-se-1999.html
- Wikipedia — Honda Gold Wing (GL1500 generation, flat-six, electric reverse, model trims): https://en.wikipedia.org/wiki/Honda_Gold_Wing
- Honda GL1500 Owner's Manual, Specifications page (ManualsLib p.111 — bore/stroke, displacement, compression, oil/fuel capacity, spark plug, idle): https://www.manualslib.com/manual/598692/Honda-Goldwing-Gl1500.html?page=111
- Honda GL1500 Owner's Manual, Engine Oil page (ManualsLib p.85 — API SE/SF/SG, viscosity): https://www.manualslib.com/manual/598692/Honda-Goldwing-Gl1500.html?page=85
- Honda GL1500 Owner's Manual, Crankcase Breather (ManualsLib p.84): https://www.manualslib.com/manual/598692/Honda-Goldwing-Gl1500.html?page=84
- Honda GL1500 Owner's Manual, Maintenance Schedule (ManualsLib p.78): https://www.manualslib.com/manual/598692/Honda-Goldwing-Gl1500.html?page=78
- Honda GL1500 Service Manual — Engine Torque Values (ManualsLib p.21) and 1994 service-manual extracts (spark plug 12 N·m, head bolt 45 N·m, drain 35 N·m, filter 10 N·m): https://www.manualslib.com/manual/817941/Honda-Goldwing-Gl1500.html
- Partzilla blog — Honda Goldwing timing belt/chain replacement (GL1500 belts vs GL1800 chain; 100k inspect): https://www.partzilla.com/blog/honda-goldwing-timing-belt-chain-replacement
- Steve Saunders Goldwing Forums — GL1500 timing belt replacement interval: https://www.goldwingfacts.com/threads/gl1500-timing-belt-replacement-interval.396899/
- Steve Saunders Goldwing Forums — GL1500 firing order: https://www.goldwingfacts.com/threads/gl1500-firing-order.323716/
- Steve Saunders Goldwing Forums — Rebuild the timing belt tensioner (DIY): https://www.goldwingfacts.com/threads/rebuild-the-timing-belt-tensioner-diy-for-about-20-25.313641/
- goldwingdocs.com — How to remove and replace your timing belts (GL1500 DIY, interference engine, 5–7 mm deflection): https://goldwingdocs.com/forum/viewtopic.php?t=9774
- goldwingdocs.com — Common Goldwing Failures (timing belts, water pump, sprag clutch, etc.): https://goldwingdocs.com/forum/viewtopic.php?t=27843
- goldwingfacts/goldwingdocs — Hydraulic lash adjuster discussion (no valve adjustment, replace when worn): https://www.goldwingfacts.com/threads/gl1500-setting-hydraulic-lifters.310835/
- goldwingdocs.com — Crankcase breather / PCV system and drain practice: https://goldwingdocs.com/forum/viewtopic.php?t=16115
- goldwingfacts.com — Compression test GL1500 (213 psi nominal, 185–242 range, 142 service limit @ 300 rpm): https://www.goldwingfacts.com/threads/compression-test-gl1500.338667/
- CMSNL parts — GL1500 oil cooler grommet P/N 15604-MG7-000 (confirms oil cooler fitted): https://www.cmsnl.com/honda-gl1500-goldwing-1989-k-austriakph_model3303/gromoil-cooler_15604mg7000/
- saber-cycle / Amazon — Timing belt adjuster P/N 14510-MG9-008 (GL1200/GL1500/Valkyrie): https://www.saber-cycle.com/Timing-belt-adjuster-GL1200-GL1500-Valkyrie-OEM_p_2069.html
⚠️ Items to Verify¶
- Max torque figure: ~150 N·m / ~111 lb·ft @ 4,000 rpm is most commonly cited; Wikipedia lists 110 lb·ft. Confirm the exact factory crankshaft torque figure.
- Cylinder-to-position mapping & left/right bank labeling for the firing order 1-4-5-2-3-6 — verify the physical "#1" cylinder in the factory service manual before ignition/compression diagnostics.
- Internal engine clearances and service limits — main/rod bearing clearances and selection (color codes), piston-to-bore clearance, ring end gaps, crankshaft runout: NOT verified here; take from the factory service manual for any rebuild.
- Engine torque values marked ⚠️ — camshaft holder bolts, connecting rod cap nuts, crankcase/main bearing bolts, flywheel bolt, timing-belt tensioner bolts, clutch fasteners: verify against the factory "Engine Torque Values" page before assembly. Only spark plug (12 N·m), head bolt (45 N·m), drain bolt (35 N·m), and oil filter (10 N·m) are corroborated.
- Timing belt part number & equivalents — both 14400-371-004/-014 and the Gates T274 vs T275 (NAPA 250274/250275; Goodyear 40274/40275) appear in sources. Confirm the exact correct belt for a 2000 SE VIN with a Honda parts catalog before ordering.
- Oil filter part number (15410-MFJ-D01) and cross-references — confirm current supersession/fitment for the 2000 SE.
- Oil capacity with filter — owner's manual states 3.5 L after draining; the with-filter figure (~3.7 L) is inferred. Always set level by the sight glass/dipstick.
- Oil pump arrangement and oil-pressure specification (kPa/psi at a given rpm) — not verified; confirm in the service manual lubrication section.
- Oil cooler configuration — confirmed present (grommet P/N 15604-MG7-000); confirm whether discrete cooler vs integrated and its routing.
- Hydraulic lash adjuster service-limit dimension (~0.12 in cited by owners) — verify against factory manual.
- Maintenance interval reconciliation — sources show oil-change intervals from ~3,700 mi to 8,000 mi (6,000–12,000 km); reconcile the exact factory interval table in Maintenance Schedule.
- Fuel tank capacity — factory owner's manual lists 24.0 L (6.3 US gal); some spec sites list 23 L (6.1 US gal). Noted here only for cross-file consistency; detailed in Fuel System.