Smoking Norton

Good day everyone, I'm brand new to the forum. I am a US Navy pilot and have just picked up my first Norton. It's a Commando 750. Great bike! Actually, my dad picked it up and I am loaning him a bike so I can use the Commando.

Luckily, I have to earn the right to ride her. She is smoking pretty bad out of the left exhaust and leaking oil below a JB welded patch near the bottom left of the engine. I'm relatively handy around the bike and would categorize myself as "intermediate." I also feel like my systems knowledge of the aircraft I've flown lends to an understanding of the particulars of mechainical engines. I know this forum will be a great source of information. I'm not going to be able to start on it for a couple of months because I'm building a Yamaha Bobber right now. I would love any andvice on this problem that anyone may be able to offer. I know it's impossible to diagnose problems like this without tearing into her but I figure the problems could be narrowed down if you could see it. So, I've video taped the smoking and posted it on youtube. If you look closely you can see the oil puddling at the bottom. Here's the link http://www.youtube.com/watch?v=S3PNEt5GoWk

Any thoughts are much appreciated.

So you have a 70 model or so crank case pressure is going up that hose that comes out of the end of the cam shaft. If blow by on the rings is able to push oil up that breather it's going to get into your air cleaner and there's your smoke.

Very interesting norbsa. Sounds to me like the appropriate fix would be new piston rings...which would probablly indicate honing the block, new pistons and new rings...(right?)

Leaking below a JB welded patch? What's goin' on there?

Well my guess is that you may not have a problem. The bike wet sumped and because there is some wear = smoke. You need to clean the motor inside and out get just the right amount of oil in the system than ride and test in very short 5 miles trips always stopping to look for leaks. If it smokes than do Ludwig’s test. I think you may have simply overwhelmed the breathing system with oil. Lots of reading to do in old posts too.

I see oil burning on the header pipe too. Leaky primary?

Air craft are ordinarily simply complex, But Commandos are uniquely Complexly Simple! Besides cover decal on crooked : )
You need parts and repair manual - look in Technical Note post for sources.

Looks sounds like you got a ready eager roadworthy early pre-Combat 750.
Looks like normal exhaust smoke -for a while- on LH from bike leaning to LH on side stand so intake valve guide working it out. Oil will slowly drain from tank through gear pump into crank and into sump. As long as enough oil left in tank to run a few seconds pump returns twice the input back to tank. Piston blow by tends to pressurize insides so oil tends to come out many places in essentially elastic engine seams. Most common improvement is just PCV valve stuck in breather to tank hose, but expensive upgrades can improve to pull a vacuum. This of course can lead into NEVER ending upgrade life style.

Moto, if smokes on throttle up > rings, if smoke on throttle closed > valve guides.
Moto, If seems like carbs, first suspect electrics.

Manual listed fluid levels are all too high, so best to follow manual then watch the mess and smoke clear up over time and seek natural just sufficient levels
and use that as your calibration. Below dip stick in tank and just below triplex chain in primary. Forks need 175 ml fluid though, not the 150 manual lists.
Forks can leak and blow onto engine-etc to fool ya where its coming from too.

WARNING CAUTION!!, Primary chain tightens ALOT when hot, MUST be checked
hot to know correct slack when set cold. Only one over tight primary event can tweak all shafts connected.

Commando's should go smooth in early 2000 rpm and out handle bicycles in sharp turns - which can fool you in a seeming mild powering up sweeper where the resonace can build up - rear patch pivioting on rear isolastic to slap at front isolastic to wiggle forks back into chassis to rear tire >> for flopping fish off dock, aka Hinged Handling. Every cycle will do this, just not as soon as un-control Commandos. Best way to find safe limits and know when a tire is leaking is to ride a bit on each tire ~1/2 low air - then both, and do zig zags in a lane.

You can enter a state of reversed control reactions, very very slight before a
full blow out or while creeping up on elite sports bikes entering a sweeper!!!!
Learn that feeling, just like stall onset to the bones and stay upright about no matter what. Will feel like a slight wind eddie effect, at first before surprise.

I've a triple rod linked '72, Ms Peel that can not be forced into any handling upsets NONE! I'm not a pilot but have been tossed around in sail planes, fighter trainers and crop dusting inverted helicoppters and a fan of railed roller coasters. I truly suspect I can jerk higher instantaneous G's than anything but a tunnel hull race boat or direct impact ricochets. I get tunnel vision and need breath control to hold the loads in turns, which rather exceed two tire traction states of fat tire traction controlled race bikes i consider parking lot cone corner cripples now. Ms Peel enters reversed control states on purpose to leave aero control surface flight into pure ballistic and recoil reaction controlled crashes!
When Ya get bored with Navy flight envelopes, except 'Maybe' the deck launch
let me know. I only see elite sport bikes as pure straight line sprinters too.
Peel pulls more G's than them by combining forward and radial vectors without subtraction of divided tire traction. Only thing that pulls harder on my wrists in turns is slalom water skiing. But someday will try it on race track w/o bluff face or guard rails with in feet of face, so maybe can exceed even that!
Not accessible on quaint delightful standard grunty Commando's, bad as some get.

Steve hobot Shiver
NW Arkansas Ozarks, not too far from reaching Ozone on Hwy 21.

I have to say "diito' with what hobot shares. Especially his statement of ...

But Commandos are uniquely Complexly Simple! Besides cover decal on crooked : )

I had to laugh !!! Personally, I would fix the "crooked stickers' first (cause' I'm just that anal about em') ... THEN, worry about oil leaks and other issues. (chuckle)

Welcome flyboy from a ground pounding former marine.
Nortons are like vintage war birds when the oil stops leaking thats when the problem begins :shock:
Had a crew chief tell me that once on a CH-46
Welcome and ask away.
They are a blast to ride.
Thank you for keeping us safe
Marshal

I concur with Ludwig and Norbsa, I'd love to concur with Hobot but I don't actually speak Klingon!
Since a Commando utilises a dry sump system (well notionally at least) the oil level on a Norton must be checked with the engine warm, running and having run for a good few minutes. The oil drains into the sump if left for any length of time and a simple look inside the tank would give the impression that the oil level in the tank is low, thus many new owners top up the oil to a much higher level than is desireable. I would recommend as a starting point removing the large sump plug from the bottom of the engine and draining whatever oil is in there, then check the level in the tank - you would be well advised to run the level about half way between the upper and lower dipstick marks as it may also smoke if it is set at 'Full'. While you have the sump plug out give it a clean as there is a mesh filter in there, for absolute safety the circlip that holds the filter in place should be secured with a bit of solder. After this exercise, if it still smokes then proceed along the route described by Ludwig to identify if it could be your valve guides, rather than rings. If you find that the bike has wet sumped and been left for any length of time some of the oil may have found its way into the primary drive case, this can cause clutch slips and oil leaks, so it is worth just checking the level by removing the level screw at the bottom of the primary case.

Lotsa good advice here (you'll get used to that) - mine is, I think you're best off reading them in REVERSE chronological order from above this one...e.g., check the sump first, etc.

In plain Amercian lingo, video shows very little smoking compared to many road worhty Commandos I see at rally's or home. Encouraging that it cleared up in seconds of warm up. When Norton upped the oil pressure on Commandos they had to both restrict oil flow to head and put valve seals on intake valves. There is no need of valve seals on exhaust valves as they never see chamber vacuum only pressure out when exhaust valve off seat. Most the smoke at front appears to be just flash off of oil on exterior of header. Happens ever time a header is handled with oil on hands or a wipe off from primary weepage after leaned to LH on side stand.
Oil in head tends to collect in LH rocker area to flush/smoke out a short time on warm ups. Again PCV valve in breather to tank helps a lot to keep oil from pushing out Nortons elastic engine seams. Commando's can be made oil tight, for a time but then the old worn cad plated fasteners will begin to show rust - ugh.

One of the fascinating features of Commando's and Brit Iron in general is just finding oil leaks source. Its well known that various components head to cases had porous casting issues.

One oil leak that is dangerous but w/o any evidence is front disc brake master cylinder leaking at bar end to blow away unseen and front grip completely disappearing from one good pull down to nothing the next instant. May be discovered only when tank paint begins to bubble off, thinking the slight wetness was just gas out an old cap seal. Check level at each gas stop for 1000 miles to know for sure it ain't.

Dave M,
I think it is really Gorn, not Klingon, too much simile, not enough threats.

Dave
69S

Kapla !!!!!.

??//[]\/ ,.,. ~\]~ *** ()() {}}} * ##$ =
Hahahe another space jockey that can't take real G-forces

Hobot, It looks like you threw Captn. Kirk at the ground and scored a bullseye! I note evidence on your body of the previous crashes that you refer to in earlier posts. Those arm protectors look the business where did you get them?