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.

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Piston Ring
MSRP $4.65
Part Number: 31422345384
Other Names: Engine Piston Ring More Names
Fits:
  • BMW-Motorrad:
    • F650,
    • F650GS,
    • F650ST,
    • G650GS
Piston Ring
MSRP $6.73
Part Number: 31427666228
Other Names: Engine Piston Ring More Names
Fits:
  • BMW-Motorrad:
    • F650CS,
    • F650GS,
    • F700GS,
    • G650GS
Piston Ring
MSRP $11.09
Part Number: 31427702841
Other Names: Engine Piston Ring More Names
Fits:
  • BMW-Motorrad:
    • F800GT,
    • F800R,
    • F800S,
    • F800ST
Piston Ring
MSRP $12.71
Part Number: 31422312848
Other Names: Engine Piston Ring More Names
Fits:
  • BMW-Motorrad:
    • K75,
    • K75RT,
    • K75S,
    • R100R,
    • R80R
Piston Ring
MSRP $12.71
Part Number: 31422310376
Other Names: Engine Piston Ring More Names
Fits:
  • BMW-Motorrad:
    • K1
Piston Ring
MSRP $3.82
Part Number: 31427660365
Other Names: Engine Piston Ring More Names
Fits:
  • BMW-Motorrad:
    • F650GS Dakar
Set Piston Rings
MSRP $129.89
Part Number: 11008404498
Other Names: Engine Piston Ring More Names
Fits:
  • BMW-Motorrad:
    • F750GS,
    • F850GS,
    • F850GS Adventure
Set Piston Rings
MSRP $149.16
Part Number: 11259829368
Other Names: Engine Piston Ring More Names
Fits:
  • BMW-Motorrad:
    • F900R,
    • F900XR
Repair Kit Piston Rings
MSRP $74.88
Part Number: 11251256470
Other Names: Engine Piston Ring More Names
Fits:
  • BMW-Motorrad:
    • R50/5
Repair Kit Piston Rings
MSRP $74.88
Part Number: 11251256475
Other Names: Engine Piston Ring More Names
Fits:
  • BMW-Motorrad:
    • R60/5,
    • R60/6,
    • R60/7
Repair Kit Piston Rings
MSRP $74.88
Part Number: 11251259855
Other Names: Engine Piston Ring More Names
Fits:
  • BMW-Motorrad:
    • R90/6,
    • R90S
Repair Kit Piston Rings
MSRP $74.88
Part Number: 11251335217
Other Names: Engine Piston Ring More Names
Fits:
  • BMW-Motorrad:
    • R80,
    • R80/7
Repair Kit Piston Rings
MSRP $74.88
Part Number: 11251335218
Other Names: Engine Piston Ring More Names
Fits:
  • BMW-Motorrad:
    • R80,
    • R80/7
Repair Kit Piston Rings
MSRP $74.88
Part Number: 11251335287
Other Names: Engine Piston Ring More Names
Fits:
  • BMW-Motorrad:
    • R65
Repair Kit Piston Rings
MSRP $74.88
Part Number: 11251337401
Other Names: Engine Piston Ring More Names
Fits:
  • BMW-Motorrad:
    • R65,
    • R65LS
Repair Kit Piston Rings
MSRP $202.38
Part Number: 11251342078
Other Names: Engine Piston Ring More Names
Description: For vehicles with special model classic R850R [X115A (-)] and official vehicle package [X369A (-)]. More Info
Fits:
  • BMW-Motorrad:
    • R850R
Repair Kit Piston Rings
MSRP $202.38
Part Number: 11251342779
Other Names: Engine Piston Ring More Names
Replaces: 11251341489, 11251342524
Fits:
  • BMW-Motorrad:
    • R1100GS,
    • R1100R,
    • R1100RS,
    • R1100RT
Repair Kit Piston Rings
MSRP $202.38
Part Number: 11251342847
Other Names: Engine Piston Ring More Names
Fits:
  • BMW-Motorrad:
    • R1200C,
    • R1200C Independent,
    • R1200C Montauk,
    • R1200CL
Repair Kit Piston Rings
MSRP $157.04
Part Number: 11251465178
Other Names: Engine Piston Ring More Names
Fits:
  • BMW-Motorrad:
    • K1200RS
Repair Kit Piston Rings
MSRP $112.20
Part Number: 11258566410
Other Names: Engine Piston Ring More Names
Fits:
  • BMW-Motorrad:
    • G310GS,
    • G310R
Repair Kit Piston Rings
MSRP $74.88
Part Number: 11251256477
Other Names: Engine Piston Ring More Names
Fits:
  • BMW-Motorrad:
    • R65,
    • R75/5,
    • R75/6,
    • R75/7
Repair Kit Piston Rings
MSRP $74.88
Part Number: 11251265505
Other Names: Engine Piston Ring More Names
Fits:
  • BMW-Motorrad:
    • R100/7,
    • R100RS,
    • R100RT,
    • R100S,
    • R100T
Repair Kit Piston Rings
MSRP $74.88
Part Number: 11251337398
Other Names: Engine Piston Ring More Names
Description: Only applies to "nikasil"-cylinder. More Info
Fits:
  • BMW-Motorrad:
    • R80,
    • R80/7,
    • R80G/S,
    • R80R,
    • R80RT,
    • R80ST
  • 1 more
Repair Kit Piston Rings
MSRP $128.70
Part Number: 11252343266
Other Names: Engine Piston Ring More Names
Fits:
  • BMW-Motorrad:
    • F650,
    • F650ST
Repair Kit Piston Rings
MSRP $157.54
Part Number: 11257652848
Other Names: Engine Piston Ring More Names
Fits:
  • BMW-Motorrad:
    • HP2 Megamoto,
    • HP2 Sport,
    • R nine T,
    • R nine T Pure,
    • R nine T Racer,
    • R nine T Scrambler,
    • R nine T Urban G/S,
    • R1150GS,
    • R1150GS Adventure,
    • R1150R,
    • R1150R Roadster,
    • R1150RS,
    • R1150RT,
    • R1200GS,
    • R1200GS Adventure,
    • R1200R,
    • R1200RT,
    • R1200S,
    • R1200ST
  • 14 more
Repair Kit Piston Rings
MSRP $138.23
Part Number: 11001465302
Other Names: Engine Piston Ring More Names
Fits:
  • BMW-Motorrad:
    • K1200GT,
    • K1200LT,
    • K1200RS
Repair Kit Piston Rings
MSRP $74.88
Part Number: 11251256474
Other Names: Engine Piston Ring More Names
Fits:
  • BMW-Motorrad:
    • R60/5,
    • R60/6,
    • R60/7
Repair Kit Piston Rings
MSRP $74.88
Part Number: 11251256478
Other Names: Engine Piston Ring More Names
Fits:
  • BMW-Motorrad:
    • R65,
    • R75/5,
    • R75/6,
    • R75/7
Repair Kit Piston Rings
MSRP $74.88
Part Number: 11251259853
Other Names: Engine Piston Ring More Names
Fits:
  • BMW-Motorrad:
    • R90/6,
    • R90S
Repair Kit Piston Rings
MSRP $72.97
Part Number: 11251335219
Other Names: Engine Piston Ring More Names
Fits:
  • BMW-Motorrad:
    • R80,
    • R80/7
Repair Kit Piston Rings
MSRP $74.88
Part Number: 11251335284
Other Names: Engine Piston Ring More Names
Fits:
  • BMW-Motorrad:
    • R45
Repair Kit Piston Rings
MSRP $72.97
Part Number: 11251337400
Other Names: Engine Piston Ring More Names
Fits:
  • BMW-Motorrad:
    • R45
Repair Kit Piston Rings
MSRP $74.88
Part Number: 11251464247
Other Names: Engine Piston Ring More Names
Fits:
  • BMW-Motorrad:
    • K1,
    • K100LT
Repair Kit Piston Rings
MSRP $126.30
Part Number: 11257702433
Other Names: Engine Piston Ring More Names
Fits:
  • BMW-Motorrad:
    • F650GS,
    • F700GS,
    • F800GS,
    • F800GS Adventure,
    • F800GT,
    • F800R,
    • F800S,
    • F800ST
  • 3 more
Repair Kit Piston Rings
MSRP $157.54
Part Number: 11258530295
Other Names: Engine Piston Ring More Names
Description: Only in conjunction with. More Info
Fits:
  • BMW-Motorrad:
    • R1200GS,
    • R1200GS Adventure,
    • R1200R,
    • R1200RS,
    • R1200RT
Repair Kit Piston Rings
MSRP $74.88
Part Number: 11251256473
Other Names: Engine Piston Ring More Names
Fits:
  • BMW-Motorrad:
    • R60/5,
    • R60/6,
    • R60/7
Repair Kit Piston Rings
MSRP $56.49
Part Number: 11251256479
Other Names: Engine Piston Ring More Names
Fits:
  • BMW-Motorrad:
    • R75/5,
    • R75/6,
    • R75/7
Repair Kit Piston Rings
MSRP $74.88
Part Number: 11251259854
Other Names: Engine Piston Ring More Names
Fits:
  • BMW-Motorrad:
    • R90/6,
    • R90S
Repair Kit Piston Rings
MSRP $74.88
Part Number: 11251265506
Other Names: Engine Piston Ring More Names
Fits:
  • BMW-Motorrad:
    • R100/7,
    • R100RS,
    • R100RT,
    • R100S,
    • R100T
Repair Kit Piston Rings
MSRP $74.88
Part Number: 11251337399
Other Names: Engine Piston Ring More Names
Description: Only applies to authorities egypt. More Info
Fits:
  • BMW-Motorrad:
    • R100/7,
    • R100CS,
    • R100GS,
    • R100GS Paris-Dakar,
    • R100R,
    • R100RS,
    • R100RT,
    • R100S,
    • R100T,
    • R80
  • 5 more
Repair Kit Piston Rings
MSRP $74.88
Part Number: 11251460994
Other Names: Engine Piston Ring More Names
Description: For vehicles with switzerland version. *Fg K100 0 033 500/K100RS 0147 858/K100RT 0 097 101/K100LT 0 174 368/K100 usa 0 033 000 *fg... More Info
Fits:
  • BMW-Motorrad:
    • K100,
    • K100LT,
    • K100RS,
    • K100RT,
    • K75,
    • K75C,
    • K75S
  • 2 more
Repair Kit Piston Rings
MSRP $74.88
Part Number: 11251461958
Other Names: Engine Piston Ring More Names
Description: Fg* K75 6 218 477/ K75S 0 106 906/ K75 behörd 0 120 419/ K75C usa 0 132 681. More Info
Fits:
  • BMW-Motorrad:
    • K100LT,
    • K100RS,
    • K100RT,
    • K75,
    • K75C,
    • K75RT,
    • K75S
  • 2 more
Repair Kit Piston Rings
MSRP $138.23
Part Number: 11251464586
Other Names: Engine Piston Ring More Names
Fits:
  • BMW-Motorrad:
    • K1100LT,
    • K1100RS
Repair Kit Piston Rings
MSRP $202.38
Part Number: 11258549437
Other Names: Engine Piston Kit More Names
Replaces: 11251342849
Fits:
  • BMW-Motorrad:
    • R1100S
Piston
MSRP $492.70
Part Number: 11117925331
Other Names: Engine Piston More Names
Fits:
  • BMW-Motorrad:
    • R 18,
    • R 18 Classic
Piston
MSRP $213.42
Part Number: 11250000646
Other Names: Engine Piston More Names
Fits:
  • BMW-Motorrad:
    • R50/2
Piston
MSRP $297.39
Part Number: 11250000647
Other Names: Engine Piston More Names
Fits:
  • BMW-Motorrad:
    • R50/2
Piston
MSRP $297.39
Part Number: 11250000648
Other Names: Engine Piston More Names
Fits:
  • BMW-Motorrad:
    • R50/2
Piston
MSRP $263.30
Part Number: 11250000657
Other Names: Engine Piston More Names
Fits:
  • BMW-Motorrad:
    • R60/2
Piston
MSRP $277.07
Part Number: 11251250206
Other Names: Engine Piston More Names
Fits:
  • BMW-Motorrad:
    • R75/5,
    • R75/6,
    • R75/7

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