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.
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.
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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R51/3 – R68 Throttle assembly – sliding block design
For unknown reasons, the supplier of the after-market throttle assemblies for the R51/3 – R68 models (pn 32722072350), has decided the modify the design of the sliding block. The old sliding block used to have recesses to hold the cable ends, the new version does not. While in the new version the cables cannot “escape” either, the cable ends can rub against the inside of the throttle body causing unwanted wear. We therefore remove the new sliding block from the throttle assembly and add the correctly designed older sliding block. This however increases the price of the throttle assembly.
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Saddle Y-frames R25/2 – R27 and R51/2 – R68
4 versions of the saddle Y-frames are available: P/N 52 51 7 002 164: R51/2 – R68 with 8 mm holes for saddle bearing bolt 52 51 7 002 125.7 P/N 52 51 7 002 165: R51/3 – R68 with 10 mm holes for silent block 52 51 7 002 141 P/N 52 51 7 002 115: R25/2 with 8 mm holes for saddle bearing bolt 52 51 7 002 125.7 P/N 52 51 7 002 116: R25/3 – R27 with 10 mm holes for silent block 52
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