L.A.B.
FULL MEMBER
- Joined
- Nov 2004
- Messages
- 21,452
In the USA? That would be a rare beast indeed as none were officially exported to the US as far as I know as it was a European model unless perhaps it was a personal export machine.
750 Commando LH cylinder smoking at idle (warm?)
- Thread starter StephenP
- Start date
In the USA? That would be a rare beast indeed as none were officially exported to the US as far as I know as it was a European model unless perhaps it was a personal export machine.
MexicoMike
MEMBER
- Joined
- Jan 2010
- Messages
- 3,302
As mentioned, incorrectly installed spindles will cause oil to overwhelm the seals/guides. Seems unlikely if the bike has never been apart...assuming the Norton engine builder that day wasn't asleep/drunk. 
IF the bike has original seals, they are probably ineffective due to age. They become brittle over the years. Note that nowadays, many (most? all?) current engines have seals on both intake and exhaust valves. Contrary to earlier belief, oil CAN be pulled into the exhaust stream via the exhaust valve guides. I don't know if exhaust valve seals are offered by AN (or anybody else) for these bikes but I'd install them if they are and I was doing valve work.
IF the bike has original seals, they are probably ineffective due to age. They become brittle over the years. Note that nowadays, many (most? all?) current engines have seals on both intake and exhaust valves. Contrary to earlier belief, oil CAN be pulled into the exhaust stream via the exhaust valve guides. I don't know if exhaust valve seals are offered by AN (or anybody else) for these bikes but I'd install them if they are and I was doing valve work.
There is an old J. Giles song " First I look at the Purse" , But on my bikes , "First I look at the Plugs" ( Spark Plugs can tell the whole lot.) And then I look at the Ports and the Piston tops after I do the normal compression checks and a leak down test.
In the old days it was common to decarbonize the top end and check valve clearances and replace worn parts.
In the old days it was common to decarbonize the top end and check valve clearances and replace worn parts.
kommando
MEMBER
- Joined
- May 2005
- Messages
- 7,962
You have the pushrod tunnels for the exhaust valves and the other drain for the inlet valves is on the timing side that runs down into the timing chamber leaving the driveside inlet a bit lacking in draining if parked on the side stand.
concours
FULL MEMBER
- Joined
- Dec 2011
- Messages
- 10,705
"why waste time looking at the waist line… First, I look at the purse!"
Oh Waba goober made some valid points.
The J Giles band live full house album was playing on the tape deck in my 68 Ford LSD lot of the time back in high school
Back on topic, any motorcycle running modern pump gas will color plugs with OIL only
Last edited:
I've read Peter Wolf's Book "Waiting on the Moon", and heard several radio interviews on the book and his life with the band and his marriage and some of the fascinating people he met. He is a great frontman and rock n roller.
J. Geils was a " Hard Driving Band." And like I once did "Driving just as fast as I can." WBCN Boston, until Video Killed the Radio Star.
J. Geils was a " Hard Driving Band." And like I once did "Driving just as fast as I can." WBCN Boston, until Video Killed the Radio Star.
baz
FULL MEMBER
- Joined
- May 2010
- Messages
- 8,740
Try blocking the oil feed to the head to see if the smoking stops
If it does it's something to do with the head over oiling or a loose valve guide etc and not the rings
This is a standard test so don't worry about lack of oil
If you suspect the rocker spindles are fitted wrong you can easily check by removing the oval spindle covers and using a bit of wire with a small bend on the end and have a feel which way the drilling faces
If it does it's something to do with the head over oiling or a loose valve guide etc and not the rings
This is a standard test so don't worry about lack of oil
If you suspect the rocker spindles are fitted wrong you can easily check by removing the oval spindle covers and using a bit of wire with a small bend on the end and have a feel which way the drilling faces
concours
FULL MEMBER
- Joined
- Dec 2011
- Messages
- 10,705
I guess i need to look at a manual or an engine apart. I don’t see what the side stand parking has to do with it smoking, once upright with 20-30 mins on it and a couple of hard runs up to 80 mph
In the usa yes. But i misspoke apparently. From the reading i did, the first 850’s i guess in the usa at least were hi-riders, which is what mine started life as. It was converted to a roadster at some point. 7/73 build date, serial number 306279. It looks though like the mk1-a were built 9/73. I just assumed being the early 850 it was an mk1-a
marshg246
FULL MEMBER
- Joined
- Jul 2015
- Messages
- 6,077
Confuses all new owners - don't worry about it. "A" has nothing to do with when built per se. It has to do with sound more than anything. Things like different air box, different exhaust, different 2nd gear. My 310311 left the factory as a MK2A, was sold in Scotland and then imported to the US. It is too low a serial number to be a MK2A sold initially in the US. I'm not sure, but I don't think MK1A was sold in the US at all but that doesn't mean that none ever made it here.
MK1 & MK1A were being built at the same time as were MK2 and MK2A (AFAIK).
If your battery is inline with the bike, it's not likely an "A" as the battery box was different for "A" to accommodate the airbox and the battery is across the bike in an "A".
If you want more info on Norton identification, look here: https://gregmarsh.com/MC/Norton/Info/CommandoID.aspx
Norton did not operate like other manufacturers - "model year" has basically no meaning in the Norton world.
marshg246
FULL MEMBER
- Joined
- Jul 2015
- Messages
- 6,077
Re-read my post #20 this thread. Generally speaking, yes, any smoking cause by the side stand should stop after a short while of riding.
However, you mentioned that the bike leans a lot when on the side stand and Commando's wet sump if left sitting. So, you might get a lot of oil where it doesn't belong, carbon up the cylinder a lot and be confused. That's why having a look in the cylinder might shed a light on what's wrong, but I don't think that's the problem.
The problem is that when presented with the impossible/unlikely in a forum thread, each person must rely on their experience to try to help. You have an impossible/unlikely problem. There are only a few things to eliminate. No point in me saying mine again or reiterating what others have said.
Feel free to look at my signature, go to my site, look at the bottom and call me. Sometimes it's easier to work through things on the phone instead of in a thread.
L.A.B.
FULL MEMBER
- Joined
- Nov 2004
- Messages
- 21,452
The first production Mk1A is supposed to have been 306591 the model being built for the European market due to new noise regulations coming into force there so 306279 should be a late Mk1. No Mk1As therefore were officialy imported into the USA as far as it's known.
No but then yous is nowhere near first. I'm sure I read somewhere that there were no Mk1A Hi-Riders.
L.A.B.
FULL MEMBER
- Joined
- Nov 2004
- Messages
- 21,452
I'm not entirely sure the Mk1s were still being built when the factory switched to the Mk1A.
Also as far as I know the first more than a thousand Mk2s were built after 307311 before Mk2A, the first of which is supposed to be 308360 then I expect they were probably built in batches of each.
306394 was also built as a Mk1A apparently but possibly a pre-production model?
I may take you up on that. It sometimes is much easier talk through an issue, and i certainly appreciate the wisdom
concours
FULL MEMBER
- Joined
- Dec 2011
- Messages
- 10,705
Have you done a compression test yet?
As an aircraft mechanic, certainly you are in the "test, don't guess" camp.
Have you done a compression test yet?
As an aircraft mechanic, certainly you are in the "test, don't guess" camp.
