Wet sumping

Previously stuart_munroe wrote:

Went to the ES2 this morning to find a large puddle of oil under the bike. It appears to be coming from the lower breather so I assume it is wet sumping. The drain plug is rather "tender" so I thought that rather than fit a tap or valve I would drain the tank after every ride. The Pela vacuum unit looks good and has a pipe designed to fit inside the dipstick tube of modern cars. Do any of you think it could be persuaded to slide inside the feed pipe to the sump and collect the oil from the engine as well?

I don't have my ES2 manual handy but I don't think the feed pipe goes to the sump. It goes to the pump gears. A solution I have read on this site repeatedly is the use of the Velocette check valve. Have you thought of that?

Yes, the feed pipe goes to the oil pump, obvious really when you think about it. There has been lots of discussion about the pro's & con's of anti drain valves, personally, I'm not a great fan, if the oil drains from between the valve & pump, & if it's wet sumping to that extent it almost certainly will, then when you start the engine, the oil pump is sucking fresh air & won't always pull the oil through quickly enough, resulting in exagerated bottom end wear. If you have a wet sumping problem, investigate the reason & rectify that rather than trying to mask it.

Regards, Tim

Yes, the feed pipe goes to the oil pump, obvious really when you think about it. There has been lots of discussion about the pro's & con's of anti drain valves, personally, I'm not a great fan, if the oil drains from between the valve & pump, & if it's wet sumping to that extent it almost certainly will, then when you start the engine, the oil pump is sucking fresh air & won't always pull the oil through quickly enough, resulting in exaggerated bottom end wear. If you have a wet sumping problem, investigate the reason & rectify that rather than trying to mask it.

Regards, Tim

well said Tim a man with experience on such matters Wet sumping needs looking at , do not try doing improvement like fitting a tap or other devices that will only cost you in the long run yours DJ anna j

ES2's have a roller bearing big end assembly! As long as they are wet with lube oilwhen starting/running, that is their normal workingenvironment. I have never encounted a big end that is dry upon dissassembling, even after having stood for several years. So starting an engine that has air in the feed gallery is not going to do any harm. Anyway, those geared pumps soon pull oil through, just check out how quicklyan oil pressure gauge registersthat has been fitted to an earlytwin upon starting after an oil change.

Previously Paul Knapp wrote:

ES2's have a roller bearing big end assembly! As long as they are wet with lube oil when starting/ running, that is their normal working environment.

Agreed Paul, but it will soon dry out with the heat/friction generated if there is no oil supply, & if the pump is worn to the extent that it allows bad wet sumping or thereâs even a small air leak in the feed pipe connections pump side of an anti drain valve, thereâs no guarantee that it will pull the oil through quickly. I stand by my advice that wet sumping issues should be investigated & rectified rather than masked by after market additions

Regards, Tim

Agreed Tim, my Model 50 does not wet sump at all, even left standing for almost a year, while others do wet sump after 2 weeks standing onwards. My point is that when it gets that bad the problem can be fixed. The design means that some wet sumping can happen but shouldn't be an issue if you are starting your bike every couple of weeks or more. Leaving the engine on compression will help slow down wet sumping. 16H included in the above.

On another note Tim, At some stage a long term update on how your Commando is doing, running on 15/40 semi oil please? I changed my Mk 3 from Chatsworth 40 to Millers 20/50 earlier this year and it starts so much easier (Kickstart only) No wet sumping as yet with it either for some reason I can't work out, all things being equal?

Hi Neil,

I think you've got the wrong person, I've not tried 15/40, I've run my Commando's on 20/50 for years now, I used to go straight 40 or 50, but found that, as you say, with 20/50 starting is much easier, wet sumping less of a problem, top ups are less frequent & best of all, it can be bought for much less than mono grades. I've done well over 30,000 miles on one of them since changing, it gets used in both freezing & swealteringly hot conditions, & everything in between, & have had no problems so far.

Regards, Tim