BMW Motorcycle Piston With Rings And Wristpins
Engine Pistons, Rings, and Wristpins: a Buying Guide
What They are and What They Do
Pistons
These are critical parts of the combustion process in your BMW motorcycle's engine. They may seem to have a simple job -- sliding back and forth in the cylinder head bore in the block, keeping that process going -- but there's a lot more to them, not to mention plenty of parts that make them up.
For one, as they need to be both lightweight and great at conducting heat to work properly, most pistons are made of a cast aluminum alloy. Secondly, their constituent parts and features range from a head, pin bore, and pin to a skirt and rings, ring grooves, and ring lands. The pin bore is a hole in the side of the piston that receives the pin, a hollow shaft that integrates an engine's connecting rod and the piston.
The skirt, on the other hand, is closest to the crankshaft and helps align the piston as it passes through the bore. Skirts are sometimes profiled to keep the piston as small as possible and give the crankshaft counterweights the clearance they need to run right.
Rings
Piston rings create a seal between the piston and cylinder wall to close off the combustion chamber, conduct heat, and return oil to the engine's crankcase; they're commonly made from cast iron, and their configuration and how big they are vary depending on how the engine's designed and what the cylinder's made of. The ring groove, however, is a recessed area on the perimeter of the piston that helps retain the piston ring. Ring lands, on the other hand, are the parallel surfaces of the groove which help in sealing the ring.
The rings you see most often on small engines include a compression ring, a wiper ring, and an oil ring. The compression ring, you can find in the groove closest to the piston head; it helps keep the combustion chamber from leaking while the engine burns fuel. The wiper ring is the one with the tapered face in the groove between the compression ring and the oil ring; it's also a seal, but it also helps keep excess oil off the cylinder wall. It even helps capture combustion gases that get past the compression ring. Finally, the oil ring, found in the groove closest to the crankcase, does the same thing as the wiper ring, but also helps send excess oil back to the oil reservoir in the block.
Wristpins
These, also called piston pins or gudgeon pins, connect the heads of pistons to connecting rods. More specifically, they give rods bearings to pivot on during piston movement. You usually find them made of hardened steel, but these days, if your bike's high-performance, they can also be made of tool steel, as it's the most durable and designed to stand up to high horsepower. They're also designed hollow to keep weight to a minimum, with high-performance variants correspondingly even lighter-weight to enable an engine to accelerate a lot quicker.
On stock engines, piston pins get their lubrication and cooling from oil sprayed off the crankshaft as it turns in the block. In systems designed for racing or other high-performance applications, however, there's often a system of tubes directed at the pistons' bottoms which spray the oil directly onto the pins and pin bosses; this helps the pistons produce max horsepower while staving off engine failure caused by heat.
A pin can be held in place one of several ways. Most stock designs are pressed-fit, with the pin being pressed into the rod. On high-performance pistons, however, they're usually fastened with wire clips or aluminum buttons.
The Signs of Problems with Them
- A loss of compression
- Overly noisy pistons
- A seized piston
- A pin falling into a piston
- A piston locking onto the pin
Pins falling into pistons indicate that they're inadequately lubricated. Pistons locking onto pins, however, can cause engine seizure. Broken connecting rods and a busted block could result in any case. See any of these, and you should run an engine inspection, followed by replacing any of the parts the results recommend changing. You're in luck: you can order what you need, right here.
Genuine BMW Motorrad Pistons with Rings and Wristpins for Sale Online -- Shop Now
We've got a complete catalog full. Be sure to browse it by model and year; it'll make finding what's compatible with your BMW bike go a lot more quickly and easily. Buy now, and we'll ship and deliver ASAP, right to your address.
- BMW-Motorrad:
- HP2 Sport
- BMW-Motorrad:
- R 1200 GS,
- R 1200 GS Adventure,
- R 1200 R,
- R 1200 RT,
- R nineT,
- BMW-Motorrad:
- R 18,
- R 18 B,
- R 18 Classic,
- R 18 Transcontinental
- BMW-Motorrad:
- K 1200 GT,
- K 1200 R,
- K 1200 R Sport,
- K 1200 S,
- K 1300 GT,
- BMW-Motorrad:
- M 1000 R,
- S 1000 R,
- S 1000 RR,
- S 1000 XR
- BMW-Motorrad:
- R 1200 GS,
- R 1200 GS Adventure,
- R 1200 R,
- R 1200 RS,
- R 1200 RT
- BMW-Motorrad:
- R 1100 GS,
- R 1100 R,
- R 1100 RS,
- R 1100 RT,
- R 1100 S,
- BMW-Motorrad:
- F 750 GS,
- F 850 GS,
- F 850 GS Adventure
- BMW-Motorrad:
- R 100 /T,
- R 100 CS,
- R 100 GS,
- R 100 GS Paris-Dakar,
- R 100 R,
- BMW-Motorrad:
- K 100,
- K 100 LT,
- K 100 RS,
- K 100 RT,
- K 75,
- BMW-Motorrad:
- F 650,
- F 650 CS,
- F 650 GS,
- F 650 GS Dakar,
- F 650 ST,
- BMW-Motorrad:
- F 650 GS,
- F 700 GS,
- F 800 GS,
- F 800 GS Adventure,
- F 800 GT,
- BMW-Motorrad:
- F 650 GS,
- F 700 GS,
- F 800 GS,
- F 800 GS Adventure,
- F 800 GT,
- BMW-Motorrad:
- K 1200 GT,
- K 1200 LT,
- K 1200 RS
- BMW-Motorrad:
- F 650 GS,
- F 700 GS,
- F 800 GS,
- F 800 GS Adventure,
- F 800 GT,
- BMW-Motorrad:
- R 80,
- R 80 G/S,
- R 80 RT,
- R 80 ST
- BMW-Motorrad:
- G 310 GS,
- G 310 R
- BMW-Motorrad:
- F 650,
- F 650 GS,
- F 650 ST,
- G 650 GS
- BMW-Motorrad:
- F 650 GS Dakar
- BMW-Motorrad:
- K 1200 RS
- BMW-Motorrad:
- R 100 /T,
- R 100 CS,
- R 100 GS,
- R 100 GS Paris-Dakar,
- R 100 R,
- BMW-Motorrad:
- K 75,
- K 75 RT,
- K 75 S,
- R 100 R
- BMW-Motorrad:
- R 1200 C,
- R 1200 C Independent,
- R 1200 C Montauk,
- R 1200 CL
- BMW-Motorrad:
- HP2 Enduro,
- HP2 Megamoto,
- HP2 Sport,
- R 1150 GS,
- R 1150 GS Adventure,
- BMW-Motorrad:
- R 1200 GS,
- R 1200 GS Adventure,
- R 1200 R,
- R 1200 RS,
- R 1200 RT
- BMW-Motorrad:
- K 1,
- K 100 RS
- BMW-Motorrad:
- F 750 GS,
- F 850 GS,
- F 850 GS Adventure
- BMW-Motorrad:
- R 850 R,
- R 900 RT 05 SF,
- R 900 RT 10 SF
- BMW-Motorrad:
- K 1,
- K 100 LT,
- K 100 RS
- BMW-Motorrad:
- F 650,
- F 650 ST
- BMW-Motorrad:
- R 1100 GS,
- R 1100 R,
- R 1100 RS,
- R 1100 RT
- BMW-Motorrad:
- F 900 R,
- F 900 XR
- BMW-Motorrad:
- K 1100 LT,
- K 1100 RS
- BMW-Motorrad:
- M 1000 RR
- BMW-Motorrad:
- R 65,
- R65,
- R65LS
- BMW-Motorrad:
- R 100 /T,
- R 100 RS,
- R 100 RT
- BMW-Motorrad:
- F 650 CS,
- F 650 GS,
- F 700 GS,
- G 650 GS
- BMW-Motorrad:
- R 100 /T,
- R 100 RS,
- R 100 RT
- BMW-Motorrad:
- F 800 GT,
- F 800 R,
- F 800 S,
- F 800 ST
- BMW-Motorrad:
- K 100,
- K 100 LT,
- K 100 RS,
- K 100 RT
- BMW-Motorrad:
- K 100 LT,
- K 100 RS,
- K 100 RT,
- K 75,
- K 75 C,
- BMW-Motorrad:
- R 1250 GS,
- R 1250 GS Adventure,
- R 1250 R,
- R 1250 RS,
- R 1250 RT
- BMW-Motorrad:
- K 1200 GT,
- K 1200 LT,
- K 1200 RS
- BMW-Motorrad:
- C 600 Sport,
- C 650 GT,
- C 650 Sport
- BMW-Motorrad:
- HP2 Enduro,
- R 1200 GS,
- R 1200 GS Adventure,
- R 1200 R
- BMW-Motorrad:
- HP2 Sport,
- R 1200 GS,
- R 1200 GS Adventure,
- R 1200 R,
- R 1200 RT,
- BMW-Motorrad:
- HP2 Sport,
- R 1200 GS,
- R 1200 GS Adventure,
- R 1200 R,
- R 1200 RT,
- BMW-Motorrad:
- HP2 Megamoto,
- R 1200 GS,
- R 1200 GS Adventure,
- R 1200 RT,
- R 1200 ST
- BMW-Motorrad:
- HP2 Enduro,
- R 1200 GS,
- R 1200 GS Adventure,
- R 1200 R
- BMW-Motorrad:
- R 1200 S
- BMW-Motorrad:
- R 1200 S
- BMW-Motorrad:
- HP2 Megamoto,
- R 1200 GS,
- R 1200 GS Adventure,
- R 1200 RT,
- R 1200 ST
- BMW-Motorrad:
- R 1200 R,
- R nineT Pure
- BMW-Motorrad:
- F 750 GS,
- F 850 GS,
- F 850 GS Adventure
- BMW-Motorrad:
- R 100 /T,
- R 100 RS,
- R 100 RT
- BMW-Motorrad:
- R 100 /T,
- R 100 RS,
- R 100 RT
- BMW-Motorrad:
- R 1150 RS,
- R 1150 RT
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