"Unsumping" a Sumped Norton

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Stephen Hill

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Oct 28, 2009
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Has anybody tried unsumping a sumped Norton by removing the spark plugs and just kicking it over until you get enough oil back into the oil tank to start the bike?
I appreciate that I could try this and see but if it would take me half an hour of kicking and still not do much, I'd rather just learn from those wiser than me and not kill myself on a hot sweaty summer afternoon.
And yes, I appreciate that if I rode the bike more, I would not have this problem..... :)
 
A lot easier to undo the drain plug if it has wet sumped, just did mine 3 days ago from sitting since February but only had just under 1ltr of oil in the sump, only takes a few minutes to drain while checking other things before a ride.
 
It's going to make you so tired from kicking you probably won't feel like riding. As Ashman says just drain it into a clean container and dump back into the oil tank. Not sure which model you have. Some only have a single large drain plug. If you have one of those you can replace it with an aftermarket one that has a smaller magnetic plug screwed into it. Less chance of cross threading the big plug. Also do a search on the AMR wet sump fix. I've done four of those and while it may not completely cure the problem, it will make it a lot better.
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I've never bothered draining the sump prior to first start after being parked for a while.
I started my '70 Roadster with a sump full of oil a few weeks ago and it just started as usual.

I've removed the timed breather in favour of a reed valve, so crankcase pressurisation isn't a problem.
 
Guess it will only blow the crank seal if started with lots of oil in crankcase. Don't think kicking will manage. But only seen it happen once.
 
It took Norton until 1975 to positively retain the crank seal...
No point rushing these things, is there? ;)

I was rather disappointed to have to machine off the circlip retainer part of my Maney cases to accommodate the CNW primary drive pulley.
 
That is how I prime my oil system after draining the oil tank and sump, and changing out the oil filter, then refilling a new filter and filling the oil tank. Point is yes you could suck oil out of the sump with the kick start, but it takes a lot of kicking. If the sump is really full like a liter or more, it could be difficult to kick over without a breather of some type.

I don't have a sumping issue using a ball valve with an ignition shutoff switch. Generally frowned upon, but it works better than the AMR mod. Jim Schmidt has a couple of reed valve solutions if you don't already have one. So does CNW and NYC Norton.

In the olden days I removed the sump plug as Ash suggests.
 
This prompts me to get on with installing a reed valve in my1972 Combat.
I like the CNW reed valve but it seems a bit pricey when I factor in currency conversion and shipping through the border.
I will get one of the reed valves (below) and mill an aluminum housing.

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A 72 is easy to do, just put a 180 inline reed valve in the breather pipe coming out the rear of the crankcase.

Something like this

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A Yamaha EGR valve.
 
I just start it and run it, puts its self back with a little smoke, never had an issue. I now have an o ring between the seal and the sprocket, but that is only because I rebuilt the engine.
 
I have 2 reed valves instead of just one. I never drain the crankcase and refill the oil tank and I don't get more than an oily film in the belt drive primary after a few months of riding. I have one mounted on the back plate of the timing chest with 2 extra holes drilled between the timing chest and the crankcase, and I have Jim Schmit's camshaft port reed breather on the other side. The 2 of them seem to work ok. The only oil leakage is from out of the oil tank breather hole which is from atomized oil from the air inside the oil tank
 
Stephen Hill said:
Kommando, do you just use the upper unit in the photo?
Click to expand...
On my commando I use only half of the top unit
The half with the reed valve
Its bolted to flat blanking plate on the back of the timing chest where the starter motor was designed to go on a 750
 
Last edited:
maaseyracer said:
I just start it and run it, puts its self back with a little smoke, never had an issue. I now have an o ring between the seal and the sprocket, but that is only because I rebuilt the engine.
Click to expand...
Jerry Doe posted a vid awhile back demonstrating just that on his 850 - idling while looking into the oiltank as it filled back up. Maybe someone can find and repost that vid here.
 

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