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

Very informative video! https://fb.watch/gQycYmmz_h/    

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.

The BMW specification for the radial clearance of the conrod big end & crankpin is based on the use of slightly spherical rollers in some of the crankshafts. The use of spherical rollers prevents the rollers from “biting” when the crankshaft flexes at high RPM. Today the new FAG Dürkopp conrod sets are equipped with cylindrical rollers. This requires a slightly larger radial clearance to prevent the rollers from getting stuck when the crankshaft flexes at high RPM. Spherical rollers (used) are identified by the wear track in the center of the roller:                
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These photos show the difference between the Noris keys and the replica keys. This can help to identify the cause of malfunctioning ignition switch.      

If the valve adjusting screws have reached their end and there is still insufficient valve clearance, the cause may be (a combination of): the valves sit too deep in the valve seats the cylinder head sleeves have sunk deeper into the cylinder head over time. In our experience, the sleeves at the exhaust side sit usually deeper than at the intake side. Below an example of 2 R27 cylinder heads. The RHS sleeve at the intake side of cylinder head 1 has a height of 88.47 mm The LHS sleeve at the exhaust side of cylinder head 2 has a
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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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Flow chart to identify a 2 cylinder crankshaft. Click on the flow chart and table for larger images, click <- arrow in your browser to return to this page.                                                            

This list shows the part numbers for all parts that need to be changed in case of a conversion to 12V  

Click image for table    

This video shows the repair of the idle mix thread: a thin alu-bronze bush of M8 / M7 x 0.75 is installed in the carburettor, realizing a very wear-resistant and strong thread Click this image to watch the video on Youtube:  

In this video a method is shown to remove the old and install new tappet guide bushings from a 2 cylinder engine. The new bushings with an outer diameter of 24.97 mm have an interference fit with the crankcase. After installation, the bushings ID needs to be reamed / honed to give a tappet clearance of 0.02 – 0.04 mm Click this image to watch the video on Youtube: