Pistons aren’t round

It’s a wide spread misconception that pistons must be round / cylindrical. The opposite is true, This is a new Kolbenschmidt R27 piston 68.50 mm:               From the Internet: Profile: If you roll a piston across a flat surface, you’ll notice it doesn’t roll in a straight line. This characteristic is called profile. Aluminum conducts heat significantly, so pistons are designed with a taper. The top of the piston (near the crown) has a smaller diameter than the bottom (near the skirt). The skirt itself is shaped like a barrel. This taper allows the
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Denfeld vs Pagusa saddle

The only difference between the Denfeld en Pagusa saddle is the saddle deck. There are small differences between the saddle deck frames: the shape of the frame and the front threaded bolt. The Pagusa saddle bolt it is a bit longer and has a spacer so that the front of the saddle deck sits +- 1.5 cm higher compared to the Denfeld saddle deck. The grain texture of the Denfeld rubber saddle deck surface is finer than the Pagusa grain texture. There is no quality difference All other parts are the same: subframe, Z-bracket, rubber spring, spring stop piece, mounting
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Light and horn switch, left side – quality issue

The Light & Horn Switch with P/N  61 31 8 048 162 does not properly fit on the Clutch Lever Assembly with P/N 32 72 2 072 112 The cause of this problem is clarified in the photos below. The ends of the switch housing extend too far into the clutch lever assembly. As soon as both parts are mounted together on the handlebar, the switch housing is pushed outwards, so that the switch housing can no longer be hooked behind the cam.  

R51/3 – R69S engine gear set dimensions

Based on a sample of 74 gear sets, this graph shows the frequency of the different gear sets and the spread around the target dimension of +0.

Gearbox cam plate comparison

Comparison of the different gearbox cam plates used in the R24 – R27 and R50 – R69S models. For more information about the R50 – R69S shifting system, click following links: Smooth shifting R50 – R69S R50 – R69S Old and New style shifter mechanism  

Upper valve spring cap 11 34 0 026 180

There are 2 versions of this spring cap available in the market. The top one is correct. The valve in the lower black spring cap is too deep, with the result that the force exerted by the valve spring is slightly less.                                              

Seal material property comparison

A “strenght & weakness” overview of the different seal materials available in the market.

Oil slinger screw

The oil slinger screws are not available from BMW anymore. Most suppliers now offer a general purpose DIN 963 M6 x 10 screw. However, the head of this screw is higher than that of the original screw: the head of the screw protrudes above the oil slinger surface. This may be undesirable in some cases. We now supply oil slinger screws with the same dimensions as the original screw.

Ignition keys

These photos show the difference between the Noris keys and the replica keys. This can help to identify the cause of malfunctioning ignition switch.      

Bearings

All standard bearings we supply, are either from FAG or SKF. FAG is a brand of Schaeffler Group Germany. SKF is a Swedish company. Both companies have factories in different locations around the world. The country of origin is stated on the packaging. These can be countries like Portugal, Slovakia, USA, Republic of South Korea, India or China. We regularly have to explain that “made in China” is not a parallel import of Chinese brand bearings.               We purchase our bearings from ABF Bearings. ABF Bearings is a major worldwide ISO certified distributor of
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New cylinder heads R51/3 – R60/2

Our price of these cylinder heads is higher than the price of other suppliers, for the following good reasons: 1. The valve guides are checked and reamed if needed. Some guides require upto 0.02 mm reaming.  Without these adjustments, the valves would get stuck quickly. 2. We replace the supplied non-rotating valves with rotating valves. 3. The cylinder head mating surfaces are flattened in case of visible/palpable edges in the mating plane or “curved” surfaces. The depth of the mating surface is measured, to make sure that the height of the collar on the cylinder does not exceed the depth
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Turn signal switch & switch support

Turn signal switch with P/N61318048152AM will only fit with switch support with P/N32722072175. The original Magura switch support is too high, so the switch does not connect properly to the switch support. This leaves an opening visible.