Smoking MK2a

MCP · Feb 6, 2023

Lineslinger said:
I am of the opinion your cylinders, one for sure, are not breathing properly.
I believe you stated new carburetors.

Laser temperature gauge on the header pipes? Measure air intake/flow/volume? Head temperature at carbs. and exhaust ports? Carb manifolds insulated?

Those cylinder temps. should be close to very close and the header/exhaust pipes should reflect that.
Let us know what you come up with when it dries out?

Thanks for the suggestions. I don't know how to measure the intake/flow/volume, but I did get some temperatures, see below.

I checked in 3 spots right & left at 4 & 6 minutes.

1) At the headers where they exit the head Header R Header L
2) At the mufflers (peashooter seam where it tapers) Muffler R Muffler L
3) At the head where the carb manifold meets the head Head at manifold R Head at manifold L

I do have new carbs, but I had the same issue with the originals.

Guess my theory of different packing in the mufflers is out the window.

MCP · Feb 6, 2023

seattle##gs said:
You have the kind of problem that promotes premature aging. I can add 2 more in the exhaust dept.
#1...The Twittering Exhaust Pipe...nearly undetectable even after you know what to look for. I said PIPE, not muffler.
#2....After market mufflers with a restriction installed leaving only a passageway no bigger than a quarter. That kept me going for a couple of months, never suspecting that some muffler maker would cripple their own product with a restrictor plate. I only found it when I had the bike up on the lift and happened to look over and see the restriction. I've seen this type of restriction in Atlas and Dominator mufflers but never in peashooters. I put on a set of used peashooters and the problem disappeared. I've never forgotten that lesson. HINT TO DOMMIE AND ATLAS OWNERS: get the biggest drill you can find run it down your mufflers...instant power improvement and a better sound.

seattle gs - thanks, I'm not following your suggestions.

marshg246 · Feb 6, 2023

MCP said:
Thanks for the suggestions. I don't know how to measure the intake/flow/volume, but I did get some temperatures, see below.

I checked in 3 spots right & left at 4 & 6 minutes.

1) At the headers where they exit the head Header R Header L
2) At the mufflers (peashooter seam where it tapers) Muffler R Muffler L
3) At the head where the carb manifold meets the head Head at manifold R Head at manifold L

I do have new carbs, but I had the same issue with the originals.

Guess my theory of different packing in the mufflers is out the window.

Right hotter, yet right fouling? I would consider this easy if it were right hotter, left fouling. Still, hotter usually means leaner which could be an air leak or air screw out too far. First, I would remove the entire left exhaust and make sure there is no obstruction anywhere. Look especially where it meets the head. I've seen where the pipe is cut too long and the outer flange part is weld on creating a "catch" inside the pipe.

If not that, I would ensure that the carbs are perfectly manually synced, that the needles move with the slides, that the air screws are out exactly the same amount and that the slides are open exactly the same amount at idle.

MCP · Feb 6, 2023

marshg246 said:
Right hotter, yet right fouling? I would consider this easy if it were right hotter, left fouling. Still, hotter usually means leaner which could be an air leak or air screw out too far. First, I would remove the entire left exhaust and make sure there is no obstruction anywhere. Look especially where it meets the head. I've seen where the pipe is cut too long and the outer flange part is weld on creating a "catch" inside the pipe.

If not that, I would ensure that the carbs are perfectly manually synced, that the needles move with the slides, that the air screws are out exactly the same amount and that the slides are open exactly the same amount at idle.

Thanks Greg
Correct, right fouling, right smoking prior to the head work done. So far (haven't ridden yet) but at idle, no more smoke on the right side now. To early to say on the fouling.
- the entire left exhaust was off, just put it back on after the head work - no obstructions
- air screw out too far, its possible, but a reminder, this heat issue was like this before I replaced the original carbs last summer. And I didn't replace the carbs for the heat issue though (a tuning issue); but I did purchase carbs from the same person who installed them, a qualified Norton mechanic. So same heat issue new carbs. I will check the air screw though.
- the needles and slides were manually synced

marshg246 · Feb 6, 2023

MCP said:
Thanks Greg
Correct, right fouling, right smoking prior to the head work done. So far (haven't ridden yet) but at idle, no more smoke on the right side now. To early to say on the fouling.
- the entire left exhaust was off, just put it back on after the head work - no obstructions
- air screw out too far, its possible, but a reminder, this heat issue was like this before I replaced the original carbs last summer. And I didn't replace the carbs for the heat issue though (a tuning issue); but I did purchase carbs from the same person who installed them, a qualified Norton mechanic. So same heat issue new carbs. I will check the air screw though.
- the needles and slides were manually synced

OK, lets assume for the moment that it is carb related and all the temp testing you did was on the center stand at an idle. And, let's assume that the exhausts are identical and the air cleaner(s) too and the carbs are perfectly sync'ed. Different heat = different air/fuel mixture = different air screw setting. If they are out 1-1/2 turns each, then something is wrong. Air leak, fuel height too high and flooding on one or both carbs. Fuel height too low and starving on one or both carbs. Not actually sync'ed (one throttle stop in more than the other)

Lineslinger · Feb 7, 2023

What Marsh 246 said.
Consider, Its not too big a deal for you mechanically, to pull your carburetors and reassemble. Clear all ports, check float bowl level etc etc.
That way YOU will know for sure they match.
I am wondering about a blocked/clogged passage or float bowl level that is incorrectly set.
You can do this. Its not that complicated and the understanding of how it all interacts is knowledge you will always have.

73NortonRider · Feb 20, 2023

hhh said:
The rings rotate in use. Ring gap orientation is a myth. But upside-down is bad.

A myth that this is a myth. Its been proven to be a problem if not installed as recommended by the factory. After redoing what I had mistakenly did and correcting the rings the bike stopped smoking.

hhh · Feb 20, 2023

73NortonRider said:
A myth that this is a myth. Its been proven to be a problem if not installed as recommended by the factory. After redoing what I had mistakenly did and correcting the rings the bike stopped smoking.

I could understand how you don't want the gaps at the thrust points, but why do some bikes have pegs to hold the rings in place if they don't rotate? Also, I just read some larger diesels actually detect if the top ring stops turning as a warning of engine condition (but haven't verified this.)

Torontonian · Feb 20, 2023

I would replace both intake seals with Teflon type , not Norton plastic type .

The cylinders and bores will last forever with regular oil changes .

The valves and guides and seals need a machine shop long before that .

Grandad · Feb 21, 2023

Ring pegs - only engines I've worked on with piston ring pegs have been two strokes where the pegs are designed to prevent the rings from rotating such that the end gaps then align with the gas transfer ports, something that can cause untold damage.

MCP · Mar 25, 2023

WZ507 said:
This might possibly shed a ray of light on the temperature difference from R to L side.

WZ507 said:
This might possibly shed a ray of light on the temperature difference from R to L side.

Cold Case #001 - The Case of the Cold Pipe (2015)

The Case of the Cold Pipe The following is a description of the suspect. • Bone stock '74 850 Roadster with 10K mi • Carburetion - stock Amal 932 Concentrics freshly rebuilt, new air cleaner, synchronized via vacuum gauges at idle and on the road. • Ignition - points, auto-advance...

www.accessnorton.com

Big thanks to WZ507 for posting that long ago.

Problem solved, why one muffler gets hot and the other is cooler.

Since my last post I had the carbs off, swapped the coils, swapped the leads, changed the black box (dont know the proper term) on my Wassell, nothing worked. So this morning I swapped the pea shooters, whats there to lose, and voila, now the left heats up and the right stays cool.

I bought the pea shooters at the same time so I'd think thats odd.

My next question is there any harm to the motor when its like this?

Torontonian · Mar 27, 2023

MCP said:
Big thanks to WZ507 for posting that long ago.

Problem solved, why one muffler gets hot and the other is cooler.

Since my last post I had the carbs off, swapped the coils, swapped the leads, changed the black box (dont know the proper term) on my Wassell, nothing worked. So this morning I swapped the pea shooters, whats there to lose, and voila, now the left heats up and the right stays cool.

I bought the pea shooters at the same time so I'd think thats odd.

My next question is there any harm to the motor when its like this?

Just received 2 new peashooters mail order source un-named and both are different .
Not noticeable at first glance but can see they are .

hhh · Mar 28, 2023

Torontonian said:
Just received 2 new peashooters mail order source un-named and both are different .
Not noticeable at first glance but can see they are .

I bought a pair once that looked identical but the flutes were rifled on one and straight on the other. I have no idea if it made any difference.

MCP · Mar 28, 2023

Torontonian said:
Just received 2 new peashooters mail order source un-named and both are different .
Not noticeable at first glance but can see they are .

Thats interesting.

My pipes are Wassell stamped "Made in England", thats the only marking; bought new together in June 2021. I like them and I've ordered another one which I'll have in a couple weeks, so I plan to swap the cooler pipe for the new one. I'll see what happens.

Yesterday I started the bike, a little smoke from the left side (thats a first), then it cleared, nothing from the right (thats a first). Exact opposite to what I've had since I got the bike running in May last year.

MCP · Apr 13, 2023

Bringing this to a conclusion, I received and installed the new muffler - it looks identical; and in the end the muffler that I considered hot (relative to the other - cold muffler) was the problem. I now have 2 mufflers running at the same temperature.

Also, the hot muffler regardless what side it was on produced a little bit of smoke, the cool side didn't, bizarre. With the new pipe on now, both sides are slightly smoking, but once warmed up the smoke disappears. The bike has only 150 miles since new rings so I'm told thats normal.

I have a great local supplier and he's taking back the other muffler. Thanks to everyone's input, and I hope this helps someone in the future.

Smoking MK2a

MCP

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Cold Case #001 - The Case of the Cold Pipe (2015)

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