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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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
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.
Exhaust pipes comparison R25, R25/2, R26, R27
Without direct comparison, it can be difficult to distinguish the difference between the R25-R25/2, R26 and R27 exhaust pipes. This photo shows how you can easily determine the type of exhaust pipe: The R25, R25/2 exhaust pipe is significantly longer at the straight end than the R26 exhaust pipe:
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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Rim width
The width of rims can be measured in 2 different ways: the inside or the outside. This means that one and the same rim can be indicated both in (for example) 2.15 “and 3.08″ WM2: inside 1.85″ (47 mm) outside 2.72″ (69 mm) WM3: inside 2.15″ (55 mm) outside 3.08” (78.2 mm)
BING jets
BING jets are stamped with numbers, such as 35, 40 (idle jets) and 110, 115, 120 etc (main jets). One would expect that these numbers refer to the diameter of the jet bore, however this is not the case. This is confimed by the company BING in Germany. A few examples of main jets measured with a wire / jet gauge: BING 44-051 main jet 130 = gauge 120 (= 1.2 mm) main jet 125 = gauge 110 (= 1.1 mm) main jet 120 = gauge 105 (= 1.05 mm) main jet 110 = gauge 95 (=0.95 mm)
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Matra 282 tool
We mill 2 planes on the threaded bushing so that it is possible to use a 22 mm wrench on the threaded bushing. This is necessary in cases where (for instance) the crankshaft bearing is glued to the bearing journal, to prevent the threaded bushing from rotating while tightening the central bolt