Oil tank vent options

Greetings,

I have a 72 Interstate.

Currently I have the oil tank vented with an 8" length of tube to a small filter behind the battery box, it's gets kinda messy back there.

I'm a triumph guy, and I route the crankcase/oil tank vents on my triumphs under the rear fender to the back of the bike.

Has anyone done that with the Norton oil tank vent?

Thanks for all replies.

Phil

10drum said:

Greetings,

I have a 72 Interstate.

Currently I have the oil tank vented with an 8" length of tube to a small filter behind the battery box, it's gets kinda messy back there.

I'm a triumph guy, and I route the crankcase/oil tank vents on my triumphs under the rear fender to the back of the bike.

Has anyone done that with the Norton oil tank vent?

Thanks for all replies.

Phil

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Haters gonna hate! I prefer the oil tank vent to connect to the air filter with the side-mounted oil tank. Unless the oil tank is over filled there should only be air and possibly the slightest bit of oil mist. IMHO, that oil mist, if any, is actually good for the carb(s).

marshg246 said:

Haters gonna hate! I prefer the oil tank vent to connect to the air filter with the side-mounted oil tank. Unless the oil tank is over filled there should only be air and possibly the slightest bit of oil mist. IMHO, that oil mist, if any, is actually good for the carb(s).

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My bike has a CNW stater so I can't vent the tank into the carbs.

10drum said:

My bike has a CNW stater so I can't vent the tank into the carbs.

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For K&N air filters, simply drill a hole into the rear of the filter and use a kitchen sink rinser hose to connect to the oil tank vent. It's a short distance and the hose nipple that is integrated stays inserted without any need for a fastener.
BTW, I have a friend with a '72 Commando who vented his along the rear fender loop and I don't enjoy riding behind him :-(

10drum said:

My bike has a CNW stater so I can't vent the tank into the carbs.

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If you have the cNw air filter, you can add an adapter to its back whether you have the dual filter for Amal carbs or a single for Mikuni filter.

Where you vent it kind of depends on how much oil comes out. If it "gets kind of messy", then you should be venting it into a catchment bottle. I have run vents down to the lower center the bike, offset so it would never get on the rear tire. But nothing really ever escaped so I wasn't too concerned. I have followed a friend who vented his Norton along the rear fender, Triumph style, and when I followed him on the highway I was sprayed with oil droplets. He should have been using a catchment bottle.

May be as he had a 72 Cdo , he had scavenge problem and breather too...

These are all interesting replies, I don't think I need a catchment bottle. when I said messy, nothing is dripping. I think the oil mist sort of fogs the area, combine that with road grunge, it gets kinda messy. I may try routing it out the back, I'm not going to route it to the carbs, it's tight enough getting the air cleaner in and out as is.

See post # 240 page 12 ?

I run a 1ltr catch bottle for my engine breather as well for my oil tank breather, the bottle sits in between the rear engine mounts, the hoses sit down to the bottom of the bottle and I have the hoses go in from the top of the bottle as well another vent hole at the top of the bottle to let the air escape, I been using this set up for over 35 years and in that time have only had a small amount of oil on the bottom of the bottle being a clear plastic bottle you can see if any oil get in there, no mess at all and not blowing any oil into the air filter or on the road.
If you are getting too much oil from your oil tank breather then you are over filling your oil tank.

Lineslinger said:

View attachment 116058View attachment 116059

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Nice and neat. Lineslinger can you say where you sourced that little gem?

Lineslinger said:

View attachment 116058View attachment 116059

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Basically that is how I vented my oil tank, but I ran the hose down and tucked the filter behind the battery box. It might be best to keep the filter above the top of the tank as you have, to allow the oil mist that may condensate to drain back to the tank.

Lineslinger said:

View attachment 116058View attachment 116059

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Nice! I use similar K+N breathers on my GTO’s valve covers, got them from Summit, but your’s looks smaller than mine.

I’d suggest there’s nothing wrong with routing it over the mudguard if you want to.

But I’d also suggest there’s no ‘need’ to do so. FWIW I just route mine straight down, behind the gearbox.

There really shouldn’t be much coming out of that hose. If there is then I’d suggest it’s likely that you're over filling the tank.

Also, the reed valve breathers already mentioned earlier do a tremendous job of reducing the overall frothing and turbulence in the oil tank.

Without a reed valve breather you have 750cc of air pumping back and forth every revolution. At a steady 4,000rpm cruise that’s 67 times per second, or 50,250cc of air per second, that’s a lot of frothing / misting going on !! A reed valve cuts this dramatically.

Cuppy said:

Nice and neat. Lineslinger can you say where you sourced that little gem?

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Cupping,
Look up Uni-Filter.They make one that’s 1 1/2” diameter that works well for me.
Mike

10drum said:

Basically that is how I vented my oil tank, but I ran the hose down and tucked the filter behind the battery box. It might be best to keep the filter above the top of the tank as you have, to allow the oil mist that may condensate to drain back to the tank.

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I had the components already in my shop. I decided on the configuration then pieced it together and installed it.
I put a Mikes XS reed valve between the crankcase and the oil tank to relieve crankcase pressure a bit.

jamesp said:

Nice! I use similar K+N breathers on my GTO’s valve covers, got them from Summit, but your’s looks smaller than mine.

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Similar application.
I had that breather left over from a 427 Ford intake manifold build and found a use for it when restoring the Norton. Its just a filtered breather, flows easily.
The only time it could get messy is if one overfills the oil tank, I have not done so........yet.

I think the vent line in Lioneslingers photos is too short to buffer the pressure pulses. Many Velocettes use a line from engine to oil tank and a line along the fender as you suggest. It is well known that the length of the lines is rather critical to tuning the vent system to work properly. I surmise that changing the length of the line may improve the amount of mist experienced. That said, I use a xs650 reed valve between the tank and engine vent. I vent my tank to the air but have never used a filter as there I cannot envision a circumstance where dusty air would be pulled into the oil tank via the vent., assumint the line is long enough,

I most definitely do not use the vent into the filter and have blocked the filter connection to the spam can. Years ago my combat seized an exhaust valve directly opposite the vent inlet to the spam can. The result was fairly complete destruction of the right cylinder with the head, barrel, piston, and rod being destroyed and the valve head coming out the back of the engine case. BIke still ran on left cylinder.

I am convinced the engine failed because the factory oil level dipstick was too short. This was in my early years of owing british bikes and dry sump engines were still new to me. I noticed on a 3k mile trip that the oil was consumed faster when the tank was at the full level but did not deduce that this was being blown into the vent tube. I believe this was before using a pcv valve on the engine breather. Over time the oil from the vent encrusted the right exhaust valve stem. Once I quickly stopped at a rest area at the top of a mountain and I believe the exhaust valve stopped open so it did radiate its heat to the seat. On starting and riding about a half mile on the interstate, the valve seized open, the piston knocked the head off the valve causing engine carnage.

Moral, make sure you have the longer dipstick and keep the engine oil below the level that causes the oil consumption. Also, I would never again route a norton oil tank vent into the spam can. Thus, I must disagree with Greg in that I do not believe venting into the filter is beneficial to reliability.

Best to all.

ilikevelos said:

Moral, make sure you have the longer dipstick and keep the engine oil below the level that causes the oil consumption. Also, I would never again route a norton oil tank vent into the spam can. Thus, I must disagree with Greg in that I do not believe venting into the filter is beneficial to reliability.

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You do you, but IMHO, you should consider the millions of cars and motorcycles that vent into the intake track and the thousands of Nortons that have had no such trouble vented into the air cleaner!

Many here, including me, have stated that overfilling the tank can cause problems with venting. Not sure how overfilling the tank relates to oil consumption as the term is normally used.

BTW, I said nothing about reliability! I said only: "IMHO, that oil mist, if any, is actually good for the carb(s)."