420 19T 17mm-Type Front Sprocket
Steel 19-tooth front drive sprocket for compatible pit bikes, dirt bikes, mini bikes, mopeds, quads and ATVs using a 420 chain and the common 17 mm-type countershaft / retainer arrangement.
Technical Specification
- Part type: Front / countershaft drive sprocket
- Chain size: 420
- Tooth count: 19T
- Mounting-hole / shaft type: 17 mm type
- Approx. splined inner opening: 14 mm
- Approx. retainer-hole centres: 30 mm
- Approx. sprocket diameter: 80 mm
- Approx. thickness: 6 mm
- Material: Steel
- Condition: Brand new aftermarket replacement / gearing sprocket
- Quantity: 1 sprocket
Important 19-Tooth Gearing Information
A 19-tooth front sprocket is a relatively large front sprocket for many small motorcycles and pit bikes. If your original sprocket has fewer teeth, fitting 19T changes the final-drive ratio rather than simply restoring the factory gearing. A larger front sprocket generally raises the overall gearing, which can reduce engine RPM at a given road speed but may reduce acceleration.
Before ordering, check there is enough sprocket-cover / crankcase clearance for 19 teeth and enough chain adjustment for the larger sprocket.
Fitment Checks
- Confirm the chain is 420 pitch. A 428 sprocket is not interchangeable simply because the shaft size is similar.
- Compare the central spline profile and the 17 mm-type mounting arrangement with the old sprocket.
- Check the approximately 14 mm splined opening and 30 mm retainer-hole spacing against your original part.
- Confirm the retainer plate / fixing arrangement matches your engine.
- Check chain alignment after installation and replace a worn chain and rear sprocket as a set where appropriate.
Installation
Fit with the engine safely supported and follow the vehicle manufacturer's procedure for sprocket retention, chain tension and alignment. Rotate the wheel by hand after adjustment to confirm the chain runs freely and the sprocket does not contact the engine case or cover.
Application
- Commonly used on selected 50cc, 70cc, 90cc, 110cc and 125cc horizontal-engine pit-bike / ATV applications.
- Repeated aftermarket application data includes TaoTao, Coolster, SSR, Lifan, Roketa, SunL and related Chinese-engine platforms.
- Fitment must be confirmed by chain pitch, spline profile, retainer-hole spacing and 19T clearance rather than engine capacity alone.
Application note: Engine size by itself does not identify the correct sprocket. Some otherwise similar engines use a 20 mm shaft or a 428 chain, so physical comparison is essential.
Package contains: 1 x 420 19T 17 mm-type front sprocket. Retainer plate, bolts, chain and rear sprocket are not claimed as included unless they are visibly supplied with your stock.