Airbox drain pipe!

The airbox is a beautifully shaped component, but the internal design is less than optimum.
The engine breather hose spits it's output directly at the paper air filter.
It would be better if the box had a catch bottle chamber below the airbox. Like the Hinckley Bonneville.
That catch bottle would have to fill before the fluid would impact the filter element.
That would be unlikely if owner paid carefully attention to measuring correct oil level.

The breather can be re-routed , to keep it out of the air box like a NARK system . Also keep the hose the same diameter all the way out to the catch.

This is an issue on many bikes& cars now where they route the breather pipe into the air box, where it should be routed downwind of the air box, i.e. between the airbox and the inlet port.
With this set up I just left the bung(s) off on another bike, occasionally using a drill to check that the drain had not become clogged up.

Bernhard said:

This is an issue on many bikes& cars now where they route the breather pipe into the air box, where it should be routed downwind of the air box, i.e. between the airbox and the inlet port.
With this set up I just left the bung off on another bike, occasionally using a drill to check that the drain had not become clogged up.

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Sounds like a good idea since a few seconds could save a big headache!

pingu-nz said:

Hi there
1200 miles on my sport 961, Sorry to rub it in but great weather all year round in Aussie.
After first service i drained about 50ml of oil from air box.
I keep the oil on dipstick between low mark and bottom of dipstick. I have a small plug in the hose which I can remove to drain oil .
Get into the habit of draining it after every ride 100 miles or so. if you don't drain it it will build up and saturate filter. and worse go down intake .
Norton's still leak oil Its just controllable now !
Love the bike getting better every mile.
cheers
Paul

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Hello Paul , I see the small plug you are referring to on my bike . Is this the air box drain I suppose then ? There are 2 or 3 hoses routed down there and only one has the small black plug. Norton makes no mention of this in the manual !!! Is the plug to removed for draining only and then put back in while riding it ? It seems this would have been worth mentioning to the owners . Has anyone else noticed this plug in the drain hose ? Could this plug have been removed by some of the dealers and not told to the other owners I wonder ? It also makes some sense to plug the hose while riding as you may suck unfiltered air into the engine and it would prevent muck from clogging it when driving. Did anyone read about the Southbay Norton breather kit ? I saw it once and now cannot find it . Please keep the feedback coming Paul . Thanks for the input ..TA

Fascinating, but never heard of a SouthBay Norton Breater kit.
No such thing listed on their website parts page.

http://www.southbaynorton.com/index.php ... ex&cPath=2

I see, it's on the Shop/Parts page. Like the shop fix for an existing problem.
I hope it's stainless steel.
Do you have any idea were it is supposed to be bolted to?

Hi Tony
I would defiantly remove the small plastic stopper and see what comes out into a drip bottle.
Blow through it to make sure its not blocked.
Have you had the seat off and the air filter out ?
When I removed my air filter the oil was plain to see in the bottom of the air box.
As shown the oil can contaminate the air filter if left.
The other 2 breather pipes head up under the gas tank possibly 1 is overflow for filler and other is tank breather.
My bike only has 1200 miles so still running in.
Still trying to find the ideal level for the oil.
The mechanic at the first service put in the amount stated in the service manual, which is half way between the full and low mark, but it has blown out 50ml through the air box.
The dipstick at the moment shows half way between the low mark and the end of the dipstick.
I don't want to leave the plastic stopper out .
Imagine if you pull up somewhere and everyone looks at the new Norton with drips of oil under the bike !!!

cheers
Paul

Hello Again , I agree on the keep in stopper until you need to drain , and check/drain regularly . I will replace this drain hose someday with a little bit better hose. This hose is too soft and prone to pinching. I will use a hose like the overhead oil line of a TRI/BSA of the 60's/70's. Also I will look into the SBN Breather Kit. This may be the first after market part I install. Keep us proud folks...

Hello Again , Forgot to mention. You guys are saying that you will fill the oil to between the LOW mark and the end of the stick right ? On my bike that is about 5mm in length. So That means I have to get the oil level so its just touching the bottom of the stick ? That seems wrong to me. Could Norton have changed the markings on the new oil sticks ? Again there is only 5 mm , ~ 1/4th in. between the bottom of the stick and the LOW mark. Can others check this distance on their oil sticks ? I will check total length in mm , then distance to low and high marks. TA

Ok Got the measurements of the Oil Stick . Total stick length = 11 CM (110mm) This is from the bottom of the threaded cap to the end of the stick. Almost exactly 110mm.. Distance from bottom of cap to HIGH mark = 7.95 CM . Distance from bottom of cap to LOW mark = 104.05 CM. That leaves me with 5 mm of stick left to work with . Just Saying ..

TonyA, I didn't actually measure my 2013 SF but that sounds right. Just add carefully when you refill, that 1/4 of an inch is actually a couple of ounces of oil and is not that hard to hit if you are careful. You don't change oil that often anyway right? Maybe 2 or 3 times a year?

My airbox also collects a large amount of oil,which I drain to stop air filter contamination.
Having looked into the breather set up of the entire engine,it is completely wrong,the cylinder head breather,where most of the oil vapour is produced exits the rocker cover and points down towards the airbox,so any vapour runs straight into the airbox,badly designed. It seems Norton do not do enough testing on enough bikes,we are all doing it for them,then when something goes wrong it is not fixed quick enough.I won't rattle on again about stater gears falling off !!!!!!!

All I know for sure is that my drain is very active if I haven't ridden the bike in a while, especially in the cold! The evidence in on my garage floor!

My older Harleys are the same way, the newest ones vent into the intake!

I may have had a problem concerning this post, not sure yet as I have not had a chance to check the airbox, drain, or filter.

What Happened / I was my accountants office (he has Ducati's and Aprillas (sp?) So for an accountant he is a cool guy. I headed up the street and decided to give the front Brembo's and full emergency stop, four finger hard pull, just short of locking up the front end. Did this stop from about 40 MPH. The bike stalled (and yes I had the clutch pulled in LOL ) When I restarted the bike it was smoking from the exhaust. It did restart easily, but was smoking like an mid-seventies street 2 stroke. This smoking continued, but decreased, all the way home, about a 5 mile trip. Bad enough that I could not see traffic behind me.

The engine sounded good, no major knocks or mechanical sounds that would lead me to believe that something was amiss with the engine components or lube system.

Once home, the exhaust was smoking mildly at idle. I am assuming, that I had reservoir of blow-by in the airbox. I believe this fluid, under an extremely hard brake, came up and through the filter, and fouled the filter. I plan to remove the airbox this weekend to inspect the filter. I will update this post after figuring out what happened

Hello G81 Can Cycle , Do you have a plug in your air box drain pipe like my bike ? Mine is just a black nylon screw about 8 to 10 mm long and about M3 or 4 diameter. This was installed as new from the factory I assume . You know all this but I will repeat. Bike must be on its wheels not on a stand and straight up. When I remove the oil stick cap and bike is idling I see a very faint amount of vapor puffing out. This all seems normal to me. Tony.

Had a chance to troubleshoot the problem I explained above

I had a major collection of oil in my air box

When I did the heavy brake action I believe the oil surged forward and fouled the air cleaner element. This caused the smoking exhaust issue

TonyA: There was a nylon screw in the drain tube, preventing venting or draining of the air box

Even with removing the screw, it is not draining very fast. I will clear the tube and clean the box. I will run the bike in the future without the plug, or run with the plug, but remove regularly to drain the air box.

Thanks for the heads up from everyone about this problem, or I would be scratching my head trying to understand what happened.

G81,

Wow, now that’s strange.
Why would Norton deliberately put a plug in the airbox drain?
When I was overfilling my oil I had oil draining from the airbox hose continually. However, I never experienced smoking on hard braking
I doubt that my drain is plugged but, now I’ll have to check just to see how fouled my air filter is.
I think now, with the plug removed, and a new filter, you should be fine.
Thanks for sharing.

The problem is if you don't plug the airbox drain,it will end up on the rear tyre.