I am doing something very, very wrong because my air box gets a good lubing when I run the bike with the oil level at the top mark on the dipstick.
I follow this procedure to the letter. https://youtu.be/I2pkEmt_Bqw
All I get for my trouble is a tyre soaked in oil as the air-box relieves itself of all the oil it has just been given by vomiting down its drain pipe onto the exhaust and the rear of the bike. No danger of rust there then.
After less than 30 minutes the oil is below the dipstick!
In my next session, I shall run the air box drain pipe into a bottle tie-wrapped to the frame so that it does not smother the rear tyre in oil. However, that doesn't answer why it is happening at all. Any ideas?
Just for historical context, my old MkIII 850 used to do exactly the same thing when I had it. After puzzling for ages, a sage old dude told me that the dipsticks were marked wrongly and that the correct level is exactly 1/2" below the lower line. Of course, everyone knew this except me. It ran perfectly for years once I wised up.
There’s been an update for this prob for 3 years , yours hasn’t had it done, one of many updates. There are more updates as well no doubt, u might wanna consider just giving back to dealer in one piece or taking to factory for them to sought it all out,u got an uphill battle
I think they did change the length of the dipstick at some point, and I was told don't fill to the top mark and as Richard says there have been updates to the system, look at the images I posted a while ago.
Yes sounds an odd update,but the newer dip stick is longer,over filling on it’s own can result in oil in air box, the air box kit mod is plugging off vent tubes on rocket cover & new arrangement of oil separating tube things behind the barrels,& little drain bottle fitted on swinging arm that can be emptied every 3000 miles ( on mine anyway) ,check valve on oil line & another little filter, these bikes have continuously had little tweaks and mods
Thanks guys. I managed to find an hour to chat with a very helpful engineering manager (Rob) in Norton HQ. We came to the same conclusion I.E. That until she is modded up to Mk2 level in "problem" areas I am going to be in for a lot of hard work. Actually, I don't really mind as long as you guys don't get bored with my dumb questions and it doesn't get too expensive. The bike was cheapish so I recon I can spend a few quid on it. I love a challenge.
Rob says that the oil mod can be considered a two stage mod. He supplied the part numbers for stage 1 along with a technical note covering the whole thing. Some Mk 1s need the whole thing and others just need the 1st stage. I'll do stage 1 and see where I get.
As far as oil level is concerned, Rob informs me that the level must be between the two marks. The video I saw said fill to the upper mark which is simply wrong. Plus, the air box vent that comes out under the engine was supposed to be capped off. It is used to drain the air box not vent it. The cap is missing on mine. I shall be redesigning the breathing and venting arrangements when I finish replacing my girlfriend's ceiling.
Thanks for the help everyone.
Been talking to that nice Rob Jameson in Norton. I ordered and rapidly had delivered a set of parts to upgrade my MK1. The most significant piece appears to have been a new longer dipstick. Once fitted I found that I needed to suck about 3/4 liter of oil from the frame to correct the level. Or to put it another way, I had 3/4 liter too much oil in the bike as measured on the original dipstick.
Shame on Norton for not recalling the early bikes to correct a basic error of design but well done Rob for sorting me out.