Smoking 1951 ES2

Welcome to my world, theres a thread on it somewhere I posted, the most likely cause I'd the head over oiling. It's easy to test clean off the piston through the plug hole if necessary then disconnect the banjo to the head and feed it back into the tank, then go for a short ride and see if it smokes!

If it is next job is to look at the banjo and reduce the flow!

For some reason the web site won't let me cut and paste but search on ES2 engine problems

Having recently completed a restoration of my father's 1951 ES2 and had it running I was eager to get a few miles on the bike this year.

Unfortunately it smokes too much and I'm hoping someone may be able to point me in the right direction as to what the probable cause might be.

I have taken the head off and there is quite a lot of oil on the top of the piston, is this likely to be coming from the head through the valve guides or up from below?

What should I look at first?

Any thoughts appreciated.

Hi Justin

I had similar problems for a long time with my '51 ES2. Have you tried riding it? Mine was worst at tickover and when I first started it. Pull away down the road and it seemed to clear. But I was using a lot of oil!

Have a look here. This was following my problems and correctly restricting the flow to the rocker box mad a huge difference. It doesn't smoke at all now and being able to get a sensible reading from the plug has allowed me to play with carburation and get it running better than ever as well.

Barry's sketch, attached halfway down the page, showed exactly where I'd gone wrong. Check what you've got on the banjo bolt.

It's also worth checking the engine breathers are working properly, high crankcase pressure will force more oil up into the combustion chamber.

Good luck with it, they're a great bike once you get them right

Andy

Justin:

Just a thought but are you sure that you installed the piston rings correctly, that is top side of each ring to the top?

Mike

This is all explored in my thread, I can only speak of mine but it has a new piston, rebore, new valve guides valves and springs, I removed the ball from the breather and the oil pump is excellent with hardly any wet Sumping, the likely culprit Is the head being over oiled and an inspection of the banjo and bolt shows how rudimentary the oil flow control is. It's easy to temp disconnect the supply to test the theory.

Mind you Mike P said his ES2 smoked for over 1000 miles until it had run in nicely. Anyway mine hardly smokes now so I've moved on to other problems like how to move the footrests back to the swing arm!

Did it ......! http://www.nortonownersclub.org/noc-chat/technical1-singles-forum/132676687?b_start:int=0

Oh no it doesn't work .. grrrrrr!

Previously justin_peare wrote:

Sorry I can't help with the footrests, mine's a Plunger.

No prob mines a modified frame for trials!

Was that with the head off and was the sump full of oil? I.e. Had it wet sumped? That's likely to certainly exacerbate if not create the problem?

this is what i found with my es2 engine when it was smoking and burning a lot of oil. to see what was happening i removed the barrel fitted the oil ring in the bore without the piston to where it would be in normal operation ring gap to the side .placed a piece of cardboard underneath the oil ring so as to block the led torch light i was shining down the bore . viewed from underneath. the light you can see in the photo number (1). is a gap of about 2 thou between the oil ring and the bore. it was similar front and rear of the bore.

the photo was taken from a video clip so crap quality

Barry

Barry, that's interesting, I didn't try that, but it's not unusual foe a bore to wear unevenly. I assume that was a worn bore?

Hello Dan. the engine came fitted with the new piston as i found out it had been honed out. it had a mirror like Finnish on the bore. who knows it may have semi seized up in the past and probably thats why the new piston appeared, i don't know its history. at the time i had a lot of oil coming out of the exhaust rose area dripping down. and generally oil being squeezed out of every joint there was, back pressure i assume. first i did the head thinking it was that. i had new valve guides, valves, valve seats, springs, and the exhaust thread done. thinking it might be the guides worn causing the smoke, not to be it was the bore out of shape.

Barry

If it's been honed correctly I don't think the finish to the bore should be mirror like. A dull look with faint crosshatching is normal. Rings won't bed in if it's too shiny, and oil will find it's way up the bore far more easily.

Hello Tony. as you say if it had been done correctly it wouldn't have had that Finnish. i was told it was probably done with a three legged hone one with the wrong grade stones fitted. anyway i got it sorted at the end of the day

BARRY

Justin:

The cylinder bore should not be mirror-like. After the final hone and cross-hatching the bore should be a dull grey.

I suggest that you re-hone the barrel.

Mike

Don't ask me how I know.....

Have you got the correct oil ring installed? If the engine was built with 16H rings. 16H oil rings are only 1/16" wide and ES2 are 3/32". So if it has the slimmer oil rings in a wider groove it acts like an oil pump as the ring flutters in the ring groove. Smokes like bilio....

Paul

Previously justin_peare wrote:

Having recently completed a restoration of my father's 1951 ES2 and had it running I was eager to get a few miles on the bike this year.

Unfortunately it smokes too much and I'm hoping someone may be able to point me in the right direction as to what the probable cause might be.

I have taken the head off and there is quite a lot of oil on the top of the piston, is this likely to be coming from the head through the valve guides or up from below?

What should I look at first?

Any thoughts appreciated.

the ES2 piston is flat on top, original new ones are rare, I forget which side valve ones fit but they have either a small dome or a much bigger one which usually requires a bit of machining to avoid hitting the valve. New modern ES2 pistons are available from RGM and Andover Norton, both are heavier than the originals.

Dan