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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
$4.65
Part Number: 31422345384
Other Names: Engine Piston Ring More Names
Piston Ring
$6.73
Part Number: 31427666228
Other Names: Engine Piston Ring More Names
Piston Ring
$11.09
Part Number: 31427702841
Other Names: Engine Piston Ring More Names
Piston Ring
$12.71
Part Number: 31422310376
Other Names: Engine Piston Ring More Names
Piston Ring
$12.71
Part Number: 31422312848
Other Names: Engine Piston Ring More Names
Piston Ring
$3.82
Part Number: 31427660365
Other Names: Engine Piston Ring More Names
Set Piston Rings
$129.89
Part Number: 11008404498
Other Names: Engine Piston Ring More Names
Set Piston Rings
$312.80
Part Number: 11258829497
Other Names: Engine Piston Ring More Names
Replaces: 11257108478
Set Piston Rings
$149.16
Part Number: 11259829368
Other Names: Engine Piston Ring More Names
Repair Kit Piston Rings
$74.88
Part Number: 11251256470
Other Names: Engine Piston Ring More Names
Repair Kit Piston Rings
$74.88
Part Number: 11251256475
Other Names: Engine Piston Ring More Names
Repair Kit Piston Rings
$74.88
Part Number: 11251259855
Other Names: Engine Piston Ring More Names
Repair Kit Piston Rings
$74.88
Part Number: 11251335217
Other Names: Engine Piston Ring More Names
Repair Kit Piston Rings
$74.88
Part Number: 11251335218
Other Names: Engine Piston Ring More Names
Repair Kit Piston Rings
$74.88
Part Number: 11251335287
Other Names: Engine Piston Ring More Names
Repair Kit Piston Rings
$74.88
Part Number: 11251337401
Other Names: Engine Piston Ring More Names
Repair Kit Piston Rings
$202.38
Part Number: 11251342078
Other Names: Engine Piston Ring More Names
Repair Kit Piston Rings
$202.38
Part Number: 11251342779
Other Names: Engine Piston Ring More Names
Replaces: 11251341489, 11251342524
Repair Kit Piston Rings
$202.38
Part Number: 11251342847
Other Names: Engine Piston Ring More Names
Repair Kit Piston Rings
$157.04
Part Number: 11251465178
Other Names: Engine Piston Ring More Names
Repair Kit Piston Rings
$112.20
Part Number: 11258566410
Other Names: Engine Piston Ring More Names
Repair Kit Piston Rings
$138.23
Part Number: 11001465302
Other Names: Engine Piston Ring More Names
Repair Kit Piston Rings
$74.88
Part Number: 11251256474
Other Names: Engine Piston Ring More Names
Repair Kit Piston Rings
$74.88
Part Number: 11251256478
Other Names: Engine Piston Ring More Names
Repair Kit Piston Rings
$74.88
Part Number: 11251259853
Other Names: Engine Piston Ring More Names
Repair Kit Piston Rings
$72.97
Part Number: 11251335219
Other Names: Engine Piston Ring More Names
Repair Kit Piston Rings
$74.88
Part Number: 11251335284
Other Names: Engine Piston Ring More Names
Repair Kit Piston Rings
$72.97
Part Number: 11251337400
Other Names: Engine Piston Ring More Names
Repair Kit Piston Rings
$74.88
Part Number: 11251464247
Other Names: Engine Piston Ring More Names
Repair Kit Piston Rings
$126.30
Part Number: 11257702433
Other Names: Engine Piston Ring More Names
Repair Kit Piston Rings
$157.54
Part Number: 11258530295
Other Names: Engine Piston Ring More Names
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$74.88
Part Number: 11251256477
Other Names: Engine Piston Ring More Names
Repair Kit Piston Rings
$74.88
Part Number: 11251265505
Other Names: Engine Piston Ring More Names
Repair Kit Piston Rings
$74.88
Part Number: 11251337398
Other Names: Engine Piston Ring More Names
Repair Kit Piston Rings
$128.70
Part Number: 11252343266
Other Names: Engine Piston Ring More Names
Repair Kit Piston Rings
$157.54
Part Number: 11257652848
Other Names: Engine Piston Ring More Names
Repair Kit Piston Rings
$74.88
Part Number: 11251256473
Other Names: Engine Piston Ring More Names
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$56.49
Part Number: 11251256479
Other Names: Engine Piston Ring More Names
Repair Kit Piston Rings
$74.88
Part Number: 11251259854
Other Names: Engine Piston Ring More Names
Repair Kit Piston Rings
$74.88
Part Number: 11251265506
Other Names: Engine Piston Ring More Names
Repair Kit Piston Rings
$74.88
Part Number: 11251337399
Other Names: Engine Piston Ring More Names
Repair Kit Piston Rings
$74.88
Part Number: 11251460994
Other Names: Engine Piston Ring More Names
Description: *Fg K100 0 033 500/K100RS 0147 858/K100RT 0 097 101/K100LT 0 174 368/K100 usa 0 033 000 *fg K100RS usa 0 044 398/K100LT usa 0 180 968. More Info
Repair Kit Piston Rings
$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
Repair Kit Piston Rings
$138.23
Part Number: 11251464586
Other Names: Engine Piston Ring More Names
Repair Kit Piston Rings
$202.38
Part Number: 11258549437
Other Names: Engine Piston Kit More Names
Replaces: 11251342849
Piston
$297.39
Part Number: 11250000647
Other Names: Engine Piston More Names
Piston
$297.39
Part Number: 11250000648
Other Names: Engine Piston More Names
Piston
$263.30
Part Number: 11250000657
Other Names: Engine Piston More Names
Piston
$277.07
Part Number: 11251250206
Other Names: Engine Piston More Names
Piston
$277.07
Part Number: 11251253162
Other Names: Engine Piston More Names
Piston
$271.10
Part Number: 11251253163
Other Names: Engine Piston More Names
Piston
$332.80
Part Number: 11251255556
Other Names: Engine Piston More Names
Piston
$319.91
Part Number: 11251259871
Other Names: Engine Piston More Names
Piston
$332.80
Part Number: 11251259879
Other Names: Engine Piston More Names
Piston
$335.94
Part Number: 11251335414
Other Names: Engine Piston More Names
Piston
$343.34
Part Number: 11251335431
Other Names: Engine Piston More Names
Description: Only applies to cylinder. More Info
Piston
$265.82
Part Number: 11251335432
Other Names: Engine Piston More Names
Description: Only applies to cylinder. More Info
Piston
$382.72
Part Number: 11251335453
Other Names: Engine Piston More Names
Replaces: 11251265018
Piston
$400.53
Part Number: 11251335465
Other Names: Engine Piston More Names
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$382.72
Part Number: 11251335466
Other Names: Engine Piston More Names
Replaces: 11251262469
Piston
$367.48
Part Number: 11251335467
Other Names: Engine Piston More Names
Piston
$414.03
Part Number: 11251335658
Other Names: Engine Piston More Names
Replaces: 11251253949
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$420.22
Part Number: 11251335660
Other Names: Engine Piston More Names
Replaces: 11251253951
Piston
$420.22
Part Number: 11251335661
Other Names: Engine Piston More Names
Piston
$385.00
Part Number: 11251337096
Other Names: Engine Piston More Names
Description: Only applies to. More Info
Piston
$394.61
Part Number: 11251338333
Other Names: Engine Piston More Names
Piston
$498.09
Part Number: 11251464477
Other Names: Engine Piston More Names
Piston
$579.39
Part Number: 11258530237
Other Names: Engine Piston More Names
Replaces: 11258530230
Piston
$423.59
Part Number: 11258535195
Other Names: Engine Piston More Names
Replaces: 11257690407, 11257702885, 11257719358
Description: Important! Replace wristpin. More Info
Piston
$464.16
Part Number: 11258536266
Other Names: Engine Piston More Names
Description: Attention! These pistons are not allowed to be used in the repair of a replacement engine. From engine number 104ea 5016E030 onwards, it... More Info
Piston
$611.96
Part Number: 11258565633
Other Names: Engine Piston More Names
Piston
$25.82
Part Number: 11311340592
Other Names: Engine Piston More Names
Piston
$10.32
Part Number: 11421271320
Other Names: Engine Piston More Names
Replaces: 11410652120, 11411250420
Piston
$52.46
Part Number: 13111254925
Other Names: Carburetor Power Piston Kit More Names
Piston
$132.86
Part Number: 13111336609
Other Names: Carburetor Power Piston Kit More Names
Description: *Fg 01/80. More Info
Piston
$109.15
Part Number: 13111338240
Other Names: Carburetor Power Piston Kit More Names
Replaces: 13111337693
Piston
$109.15
Part Number: 13111338248
Other Names: Engine Piston More Names
Replaces: 13111337831
Piston
$15.40
Part Number: 13112343408
Other Names: Engine Piston More Names
Piston
$8.63
Part Number: 31421450515
Other Names: Engine Piston More Names
Description: Fg* K100RS (sport) sport suspension. More Info
Piston
$271.10
Part Number: 11251253164
Other Names: Engine Piston More Names
Piston
$271.10
Part Number: 11251253168
Other Names: Engine Piston More Names
Piston
$332.80
Part Number: 11251255550
Other Names: Engine Piston More Names
Piston
$332.80
Part Number: 11251255555
Other Names: Engine Piston More Names
Piston
$332.80
Part Number: 11251258294
Other Names: Engine Piston More Names
Piston
$268.13
Part Number: 11251335051
Other Names: Engine Piston More Names
Description: Only applies to. More Info
Piston
$367.48
Part Number: 11251335411
Other Names: Engine Piston More Names
Piston
$343.34
Part Number: 11251335434
Other Names: Engine Piston More Names
Piston
$343.34
Part Number: 11251335435
Other Names: Engine Piston More Names
Piston
$367.48
Part Number: 11251335436
Other Names: Engine Piston More Names
Description: *fg 09/80 r 80/7s, r 80ts. More Info
Piston
$350.47
Part Number: 11251335451
Other Names: Engine Piston More Names
Description: Only applies to. More Info
Piston
$270.60
Part Number: 11251335463
Other Names: Engine Piston More Names
Description: Only applies to. More Info
Piston
$420.22
Part Number: 11251335656
Other Names: Engine Piston More Names
Replaces: 11251251585
Piston
$420.22
Part Number: 11251335662
Other Names: Engine Piston More Names
Replaces: 11251253953
Piston
$400.53
Part Number: 11251337175
Other Names: Engine Piston More Names
Description: Only applies to. More Info
Piston
$261.60
Part Number: 11251337261
Other Names: Engine Piston More Names
Description: Only applies to. More Info
Piston
$400.53
Part Number: 11251337993
Other Names: Engine Piston More Names
Piston
$265.82
Part Number: 11251338022
Other Names: Engine Piston More Names
Description: *fg 09/80 r 80/7s, r 80ts. More Info
Piston
$461.69
Part Number: 11251338335
Other Names: Engine Piston More Names
Piston
$327.89
Part Number: 11251338418
Other Names: Engine Piston More Names
Replaces: 11251337267
Piston
$327.17
Part Number: 11251464228
Other Names: Engine Piston More Names
Replaces: 11251461930
Description: Fg* K100/2 6 308 745 /K100RS 0 147 8 58 /K100RT 0 097 102/K100LT 0 174 369 /K100RS usa 0 044 399. More Info

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