|Royal Enfield Owners Club, Humberside Area|
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|Wet sumping on RE classic Bullet engines.
Some ideas from Pete Fletcher
Bullet engines are
dry sump engines (as were most early British motorcycle engine designs)
The bulk of the oil is kept in a separate chamber at the rear of the main engine casing (where you top up the oil)
The RE has two oil pumps (although they are on the same shaft) which work on a
disc valve arrangement.
The first oil pump draws oil from the tank and pumps it through the hollow
crankshaft and so to the big end bearing.
The oil is then flung off the big end and "splash lubricates" the
crankshaft bearings, little end bearing, cylinder wall etc.
Wet sumping is when the crankcase fills up with more oil than it should while the engine is at rest.
This can happen if oil finds it way by gravity from the oil "tank",
through the oil pump and out of the big end bearing.
If the sump is "wet" when you start the engine there is far to much oil
flung around inside the crankcase as the crankshaft will be dipping into the oil.
After the engine has run for a few minutes the (larger) scavenge pump will clear
the excess oil and all returns to normal.
What to do about wet sumping
If you still have a problem it may be the oil pump discs need lapping in or the crankshaft oil seal is leaking.