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Yacco BVS 10W-30 oil, 1-litre bottle, suitable for hard-to-shift gearboxes and vintage motorcycle forks.
It makes gear changes easier, especially at low temperatures, and helps reduce gear wear and clutch sticking.
The right viscosity for vintage trial forks
The forks on our vintage motorcycles were designed to work with 10W-30 oil. Their hydraulic systems and seals are suited to this viscosity. Modern fork oil, which is much thinner, can seep past the seals and cause leaks. To maintain the performance intended by the manufacturer, always use 10W-30 oil, such as Yacco BVS.
Fork oil capacities — per fork leg
Bultaco: 125 (series 148) → 80 ml; 125 (series 156 and 185) → 100 ml; 250 to 350 (all models) → 180 ml.
Fantic: 125 Pro (type 237) → 220 ml; 200 (TX350) → 190 ml; 240 Pro → 220 ml; 300 Pro → 230 ml.
Honda: TLR 125 → 210 ml; TLR 200 → 295 ml; TLM → 277 ml.
Montesa: Cota 123 → 150 ml; Cota 172 → 130 ml; Cota 247 and 348 → 190 ml.
OSSA Trial: 180 ml. Suzuki Beamish: 195 ml.
Yamaha: TY 80 (UK or US version, Mini 80 type) → 85 ml; TY 125 and 175 → 125 ml; TY 250 (twin-shock) → 160 ml; TY 250 (monoshock) → 300 ml.
Gearbox and clutch oil capacities
Bultaco 125 to 350, including the 199B: gearbox → 600 ml (10W-30); clutch → 300 ml (ATF X).
Fantic: TX 125 to 250 models (Minarelli engine, shared gearbox and clutch housing) → 1.35 litres (10W-30); FM models (Fantic engine, shared housing) → 500 ml (10W-30).
Honda: first-model 125 TLS “Bial” and TLR 125 to 200 (shared housing) → 1 litre of mineral 4-stroke 15W-50 oil.
Montesa: Cota 123 and 172 (shared housing) → 900 ml (10W-30); Cota 247 to 349: gearbox → 300 ml (10W-30); clutch → 200 ml (ATF X).
OSSA Trial 250 and 350 (shared gearbox and clutch housing) → 1 litre (10W-30).
Suzuki Beamish (shared gearbox and clutch housing) → 800 ml (10W-30).
Yamaha (shared gearbox and clutch housing): TY 80 (UK or US version, Mini 80 type) → 500 ml (10W-30); TY 125 and 175 → 650 ml (10W-30); TY 250 (twin-shock) → 1 litre (10W-30); TY 250 (monoshock) → 800 ml (10W-30).
Please note: models specified for ATF X or 15W-50 oil require a different oil, which must be purchased separately. For the Montesa Cota 123 and 172, some period manuals specify 600 ml; the correct capacity is 900 ml. Check the recommendations for your specific version of the motorcycle.
