Too much smoke?

JCD

JCD

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A little history- I’ve just gotten this engine together. This is the second time it has started and idled since Saturday. Timing is set and carbs are dialed. Oil is returning to the tank. It was a complete rebuild along with the gearbox and every other part of the bike. 850 MK3. Standard bore. New pistons and rings, valves, seals, etc. I lightly honed the cylinders prior to the build. They were clean and measured std throughout so I got std pistons and rings. Measured ring gap and installed. I’ve built probably 7 or 8 of these machines by now. I haven’t seen smoke like this. Is this excessive smoke coming from the vent? I haven’t ridden it, nor is it close to being broken in. Plugs don’t show oil, and exhaust does not show oil or smoke. Runs cool and quiet. Thanks in advance for any input.
 
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What does it smell like? It could be condensation. If so, just go for a short ride and see if it goes away.
 
Smoke or oil mist? Is that a breather lone attached to the oil tank? Perhaps its not in the correct tank fitting? Perhaps oil level too high in tank?
 
No such thing as standard bore , new pistons and rings , with a home honing done ( no . ) . A machinist needs to measure the new pistons and bore to fit .
First oversize is your best plan , in the hands of a machinist , competent . I never do these things myself , including any valve guide / valve seat cutting work .
Expecting some flak on this .
 
It is misty. Not really smokey if that makes sense. Not really condensation either. It only starts to come out when the engine is pretty warm. I have installed the JS breather coming out the timing chest to the oil tank- this is a 750r oil tank I should add. JS breather goes to the large, raised vent and the little filter is coming out of the vent closest to the oil filler cap. The chain oiler pipe has been welded shut.
 
JCD said:
It is misty. Not really smokey if that makes sense. Not really condensation either. It only starts to come out when the engine is pretty warm. I have installed the JS breather coming out the timing chest to the oil tank- this is a 750r oil tank I should add. JS breather goes to the large, raised vent and the little filter is coming out of the vent closest to the oil filler cap. The chain oiler pipe has been welded shut.
Click to expand...
On the m3, the stock setup has a more complicated breather venting into a separator vessel then into intake manifolds.

My mk2 850 tank vents into hamcan air filter box and on into carbs.
There has been an occasion when bike was idling in the morning sunshine and I noticed a mist coming out of the hamcan. When i blipped throttle it just sucked back into the filter. I presume only detected b/c of the way light was angled to it at the time.

I suspect you are seeing more mist b/c it is dumping all out the vent pipe, none getting drawn through the carbs for burning.
 
JCD said:
This is the second time it has started and idled since Saturday.
Click to expand...
Until you get it out on the road and open the throttle to get pressure behind the rings they will not bed in. Leaving it idling will only make it worse, even with such low miles you need to get that throttle wide open even if only for a few secs.
 
JCD said:
It is misty. Not really smokey if that makes sense. Not really condensation either. It only starts to come out when the engine is pretty warm. I have installed the JS breather coming out the timing chest to the oil tank- this is a 750r oil tank I should add. JS breather goes to the large, raised vent and the little filter is coming out of the vent closest to the oil filler cap. The chain oiler pipe has been welded shut.
Click to expand...
I'm probably reading what you said wrong.

The crankcase breather connects to the pipe on the side of the oil filler tube. The pipe near the front of the tank is where the vent you showed goes.
 
Tornado writes"
No such thing as standard bore , new pistons and rings , with a home honing done ( no . ) . A machinist needs to measure the new pistons and bore to fit . First oversize is your best plan , in the hands of a machinist , competent . I never do these things myself , including any valve guide / valve seat cutting work .
Expecting some flak on this ."

Incoming flak. How do you know that JCD is not competent to measure and fit? Why would you recommend boring if the barrel is within tolerances? That's plain dumb. Your lack of competence "I never do these things myself" shouldn't be generalized in the form of advice to everyone else.
 
Stephen Hill said:
Tornado writes"
No such thing as standard bore , new pistons and rings , with a home honing done ( no . ) . A machinist needs to measure the new pistons and bore to fit . First oversize is your best plan , in the hands of a machinist , competent . I never do these things myself , including any valve guide / valve seat cutting work .
Expecting some flak on this ."

Incoming flak. How do you know that JCD is not competent to measure and fit? Why would you recommend boring if the barrel is within tolerances? That's plain dumb. Your lack of competence "I never do these things myself" shouldn't be generalized in the form of advice to everyone else.
Click to expand...
And here's your flak!
1) You disparaged the wrong guy! You should learn to use the "Reply" button to ensure that this does not happen!
2) While Torontonian's comments were a little strong, yours were ...
 
Easy boys! This is a question about a Norton and acceptable amounts of gasses venting after a rebuild. Thanks Stephen Hill for coming to the defense. I didn’t feel the need to reply to that comment, because that was not an answer to my question, it was more of a critique. We all have our skills and methods. To Torontonian, I am quite able to measure the bores, pistons and rings with more than squinted eyes and my tongue hanging out of my mouth.

I’ll get the bike on the road and brake it in slowly and heat-cycle it, torque it, adjust it, seal up any leaks and see where we land. I’ll report back to anyone interested in hearing about it. Thanks to all who were helpful on this issue so far!

Cheers
 
Back in the late 1960s/ early 70s , when I was in jr. high-school , I attempted a top end overhaul on my worn out oil burning Honda 90.
To my amazement , the rebuild fixed the problem . Even more amazing was that an older kid heard about it and brought his smokey Honda to me for the same treatment. He was willing to pay me actual money for playing with his bike!.
In no time I had a great little fun business going doing the rebuilds on Honda 50s, 90s as well as a couple of CB160s.

It all went well for a couple of years until I rebuilt the top end on a very creampuff Honda 250 Dream. Afterward the owner called to say that it was making even more oil smoke after the rebuild than it had before.

My older brother knew the owner and informed me that he was a very slow rider, always putt putting along at very low rpm/ speed.
With that bit of knowledge, I asked that he leave the 250 Dream with me for the weekend. I think he assumed that I would disassemble the engine and "fix" my incompetent work.
Instead I spent the next two days running the bike hard in the gravel pits next door as well as in the trail system on our farm. It made a piss poor mx bike, but I still had fun with it. By Sunday morning the exhaust was running clean, but I flogged it all day anyway, just to be on the safe side!
He got the bike back on Sunday night and was very happy with it afterward. I never told him how I fixed it as he probably would not have cared to hear about his pride and joy Honda Dream being thrashed mercilessly in a gravel pit!

Glen
 
Thought it was smoke we were discussing , but now it's " fog " .
I apologize , just advice from my point of view of rebuilding a Norton engine .
Enjoy .
 
worntorn said:
Back in the late 1960s/ early 70s , when I was in jr. high-school , I attempted a top end overhaul on my worn out oil burning Honda 90.
To my amazement , the rebuild fixed the problem . Even more amazing was that an older kid heard about it and brought his smokey Honda to me for the same treatment. He was willing to pay me actual money for playing with his bike!.
In no time I had a great little fun business going doing the rebuilds on Honda 50s, 90s as well as a couple of CB160s.

It all went well for a couple of years until I rebuilt the top end on a very creampuff Honda 250 Dream. Afterward the owner called to say that it was making even more oil smoke after the rebuild than it had before.

My older brother knew the owner and informed me that he was a very slow rider, always putt putting along at very low rpm/ speed.
With that bit of knowledge, I asked that he leave the 250 Dream with me for the weekend. I think he assumed that I would disassemble the engine and "fix" my incompetent work.
Instead I spent the next two days running the bike hard in the gravel pits next door as well as in the trail system on our farm. It made a piss poor mx bike, but I still had fun with it. By Sunday morning the exhaust was running clean, but I flogged it all day anyway, just to be on the safe side!
He got the bike back on Sunday night and was very happy with it afterward. I never told him how I fixed it as he probably would not have cared to hear about his pride and joy Honda Dream being thrashed mercilessly in a gravel pit!

Glen
Click to expand...
That's the olde-tyme "Italian Tune Up" method from back in the day!

Are you still accepting bikes for treatement and how much you charging?
 
The mined out gravel pit has been converted into a dog park and our old farm is a snooty, high end housing subdivision.
I'm not sure if I could get away with the Steve McQueen /Great Escape act there nowadays! :)
 
JCD said:

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A little history- I’ve just gotten this engine together. This is the second time it has started and idled since Saturday. Timing is set and carbs are dialed. Oil is returning to the tank. It was a complete rebuild along with the gearbox and every other part of the bike. 850 MK3. Standard bore. New pistons and rings, valves, seals, etc. I lightly honed the cylinders prior to the build. They were clean and measured std throughout so I got std pistons and rings. Measured ring gap and installed. I’ve built probably 7 or 8 of these machines by now. I haven’t seen smoke like this. Is this excessive smoke coming from the vent? I haven’t ridden it, nor is it close to being broken in. Plugs don’t show oil, and exhaust does not show oil or smoke. Runs cool and quiet. Thanks in advance for any input.
Click to expand...
Just one cause of excess oil smoke…the rocker spindles have oil holes that are supposed to point forward on the exhaust and rearward on the intake.
 
ILLF8ED said:
Just one cause of excess oil smoke…the rocker spindles have oil holes that are supposed to point forward on the exhaust and rearward on the intake.
Click to expand...
I’ll pull the rocker covers and see if they are puddling up. I rebuilt the head on this one and many others, and haven’t put one in wrong yet…I say yet! As I get older, I certainly question things like this! Thanks!
 
JCD said:
I’ll pull the rocker covers and see if they are puddling up. I rebuilt the head on this one and many others, and haven’t put one in wrong yet…I say yet! As I get older, I certainly question things like this! Thanks!
Click to expand...
You can quickly check where the oil hole is in the spindles....just pull off the cover plates and use a thin bit of wire with a short right-angle bend at the end....sratch it around inside the spindle tube to get the bent end to engage & locate where the hole is....
 
I've never seen any oil puddling on the exhaust side. The intake side can, but it takes a heck of a lot of puddle for it to get above the top of the valve guide seals on the intake side.

I modify the shape of the oil return holes at the side of the valve spring pockets to reduce the chances of puddling and help with the oil return. The return holes end up with an oblong funnel shape at the top.

It could be you didn't break the glaze on the bores enough with the hone work. Rings should still bed in eventually. I had a rebuild that smoked at stop lights a little for over 1000 miles because I did something similar to what you did 30+ years ago although even lighter hone by hand with emery cloth. It did stop smoking.

Sounds to me like you don't need any help with this build to me, but maybe I'm projecting. :)
 
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