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72.25mm x 1.2mm Flat Piston Ring
£25.97
1 in stock
Part Number
SP-315LR
Standard flat style piston ring with a chrome plated outer edge.
This is the closest piston ring I can find to the original Montesa Cota 315R lower rings, part number 13131-NN3-003.
There are a few issues that need to be sorted:
1. The internal diameter is about 0.5mm to small so need machining out.
2. The pin cutouts are slightly too small so need filing out to 2mm wide and 1.8mm deep so it leaves 1mm to the outer edge of the ring.
3. The end gap is a little tight, so it will need checking and gapping to the right spec.
Most ring manufactures spec a minimum of 0.004" per inch of bore, this is too allow the ring to expand as it gets hotter than the cylinder wall.
Bore size in inch = 72.25 / 25.4 = 2.844"
Ring end gap = 2.844 x 0.004 = 0.011" (0.29mm)
This is the closest piston ring I can find to the original Montesa Cota 315R lower rings, part number 13131-NN3-003.
There are a few issues that need to be sorted:
1. The internal diameter is about 0.5mm to small so need machining out.
2. The pin cutouts are slightly too small so need filing out to 2mm wide and 1.8mm deep so it leaves 1mm to the outer edge of the ring.
3. The end gap is a little tight, so it will need checking and gapping to the right spec.
Most ring manufactures spec a minimum of 0.004" per inch of bore, this is too allow the ring to expand as it gets hotter than the cylinder wall.
Bore size in inch = 72.25 / 25.4 = 2.844"
Ring end gap = 2.844 x 0.004 = 0.011" (0.29mm)
Grinding the internal diameter to the correct size.
I think the best way to alter them is to mount the new rings in the barrel and then put the barrel in the Lathe, clock the bore up so the rings are running true, then I think it would be best to use a die grinder fastened to the tool post.
| Year | 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004 |
|---|---|
| Model | 250 |
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