Dommi 88 crankshaft

I have rebuilt several Dommy engines and not removed the grub screw. If you can get it out after picking off any centerpunching and perhaps using a hammer driver it would give peace of mind to get the passage flushed through . Possibly more important if there has been mechanical breakup and loose metal fragments.

hello ,

i thought i would remove my crank grub screw .what a job i couldnt loosen it at all . it all got chewed up. so thought i would drill it out .but with it all being chewed up i couldnt make out which was the crank or which was the grub screw to drill a hole central. anyway just managed to get it right and removed what was left of it, then renewed it. personally i wouldnt bother removing it.

barry

The grub screw into the top of the crankshaft should not extend down enough to block the oilway. However it will probably have collected a small amount of debris between the bottom end of it and the Big-end oil way.  The best advice is to leave it alone.  Once the engine is running the centrifugal force will compact any rubbish in the drilling and stop it from wandering about the system

A torch light or Endoscope through the crankshaft flange should allow a good view of the oilway in that region.

Of possible interest........the first batches of Atlas bikes sent to the USA all had issues with the crankshaft oilways. These having poorly drilled passages that did not meet up properly in the crank web shoulders Consequently this restricted the oil flow to the left hand side of the crankshaft. Enough oil passed through to allow the big-ends to bed in but not enough to cope with higher speeds afterwards..