Welcome to 4-Stroke / GY6 Tech 🛠️
This section is for tuning, building, and troubleshooting 4-stroke scooters—especially GY6 (50/125/150/170/180) platforms.
Post here for:
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Valve adjustments (clearances, symptoms of tight valves)
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Big bore kits (BBK) and reliability tips
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Carbs/jetting, airbox vs pod filters, tuning for seasons
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CVK carbs vs flatslides (what changes, what to expect)
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Cams, rocker arms, head work, compression
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Ignition/CDI, stator charging issues, wiring gremlins
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Oil weight, cooling, overheating prevention
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Fuel delivery, vacuum petcocks, intake leaks
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Gear-up kits and final drive questions
To get good answers fast, include:
Scooter: year/make/model
Engine: GY6 size (50/125/150/etc) + short/long case if known
Current mods: carb size, intake, exhaust, BBK, cam, CDI, gearing
Problem or goal: top speed, acceleration, hill climb, reliability, etc
Symptoms: when it happens (idle / takeoff / mid / WOT)
Quick baseline checklist (GY6 essentials)
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Valves first. Tight valves cause hard starts, stalling warm, low power.
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Check for vacuum leaks (intake boot, vacuum lines, petcock).
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Verify fuel flow and that the auto choke works.
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If you changed intake/exhaust, expect jetting changes.
When you solve something, come back and post what fixed it — that’s how the forum becomes a goldmine 🤝
