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1947 ES2 oil grade

Submitted by simon_amos on Wed, 10/03/2010
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Singles

This question must have been answered many times but can anyone recomend a grade of oil for the 1947 ES2, I have tried a mono grade 40 but causes smoking until the engine warms, my thoughts are try a 30. The engine has been rebuilt and as good as new oil pump fitted. Tried a 20-50 that seems to make it worse. Seems most definately a oil grade problem as the warmer the engine gets the cleaner the exhaust.

Any help would be most appreciated.

Paul

Submitted by simon_amos on Thu, 11/03/2010

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I run mono 40 in mine and its fine. If its only while warming up it could be clearing out the oil that has coated the insides and run down to the sump. If the rebuild is new let it bed down a bit before worrying too much

ChrisN

Submitted by simon_amos on Thu, 11/03/2010

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Thanks Chris, probably right. I have rebuilt the engine resleeved etc and expected a small amount of smoke until the rings bedded in. I fitted a plastic oil tank to monitor the oil level and discovered it was not scavenging very well at all, after much ado change of oil pump I completely stripped the engine again, found a small crack in the casing externally where the blanking plug seals the oil suction tube. Repaired that and now have a good scavenge but annoyingly bad smoking until it warms up. It's certainly keeping me thinking.

Paul

Submitted by ian_allen on Tue, 16/03/2010

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Hi Paul.

Have you checked the pressure relief valve in the timing case and does your engine have a feed to the rear of the cylinder? I think Iâm right in saying that the pressure relief valve is in the line with this feed to the rear of the cylinder. The valve is meant to lift when the oil pressure is high (i.e. when the engineâs cold) and spray the excess onto the timing gears, if it is sticking then more oil would go to the cylinder. First unscrew the adjusting screw, remove the spring and check that the ball is not sticking. It is sometimes beneficial to give this ball a light tap with a hammer and punch to ensure that it is seating properly. According to the Norton manual it is adjusted by screwing the adjuster screw all the way home and then unscrewing it one and a half turns. It is then locked in place with a centre punch. The need of the feed to the rear of the cylinder is somewhat doubtful and I understand that it was dropped from later models. I run my ES2 on 50W oil through the summer with no problems.

Cheers.

Ian.

Submitted by phil_hannam on Tue, 16/03/2010

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Hi Paul

I am no Singles expert by a long way but have found, in the past, that smoking engines are not always caused by the obvious.

My first thought was that the piston to bore clearance was excessive. It might well be but you mention that the problem worsens with 20-50 oil. Generally, if this is the case then the grade of oil would make little difference at start up.

The next possibility was a ring problem. Gaps too big or worse still, some rings fitted upside down.I have come across two engines recently where in both cases the 'one-piece' oil control ring and 2nd compression ring were fitted inverted despite having'TOP' written on them.

Returning to the 20-50 grade oilburning issue might be the clue to finding the answer. On the twin cylinder engine you get excessive smoking when the rocker areafills up with too much oil. A lot of this extra oil then gets sucked down past the valve guides to lubricate the plugs.

The twin motors can also suffer from cracks between the valve seats, loose valve seats and poorly fitted guides that have scoring in their bores. Again, with any of these problems,the thinner oil will soon find its way into the combustion chamber while a straight 40 or 50 will take a little longer but will get there once hot.

Final thought. How good is that oil pump? Is it really getting the sump cleared quickly enough?

Phil Hannam

Submitted by simon_amos on Thu, 18/03/2010

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Seems this problem is not going to give in easily, thank you for your help Ian and Phil, I have tried so many things now I'm getting to doubt myself. Last weekend I fitted 2 new compression ring with .008" ring gaps, I did not have a new oil ring so continued with the original, did a few miles and was well pleased very little smoke if any, then this week fitted a new oil ring expecting a clean exhaust and back to square one and the excessive smoking, The engine starts fine from cold runs clean for 20secs then the engine idle increases and the smoke appears, take the head off and the piston crown is covered in oil. The piston is actually pumping oil. Why with a good set of rings and a clean bore? I have now restricted the oil feed to the rear of the cylinder but still no improvement. Remove the sump plug and may be 1/2 a cup of oil so the pump is scavenging OK. The oil ring does not appear to have a top side but have tried both ways. The crankcase breather is clear. Definately not coming down the valve guides as the 1947 singles had no rocker feed, relied on vapour only.

Can anyone tell me how much clearance the piston skirt to crank should have when at the bottom of its stroke, this may be problem as there were no standard pistons available for a 47 single, I used a 50s model piston and machined the skirt the same as the piston that came out of the engine, but as the engine was smoking badly when it came to me it is a potential problem. Rambling a little now. Did someone once say no problems just solutions, I would be most gratefull for one now.

Paul Jelbert

Submitted by ian_allen on Fri, 19/03/2010

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Hi Paul.

Clutching at straws now and I hopeI'm not teaching anyone 'to suck eggs!'- When my ES2 had a knackered bore it would smoke severely when I opened the throttle after the over-run, i.e. when the motor sucked oil up past the rings. Your mention 'breather'. Have you checked both breathers? Thereare one or twosmall possibilties - the breather that's attached to the crankcase just above where the primary chaincase fits- there are some where the union incorporates a ball-valve. If this is fitted 'upside down' - easily done - itwill serve to pressurize the cankcases and blow oil past the rings. Total disaster would be averted by the timed breather that runs throughthe crank driveshaft and exits behind the drive sprocket. Is that breather clear?

Are the valves and guides in good nick? Leaks past these could lead to excess pressure or could explain the idle increasing. The exhaust would show carbon up the stem if it was worn and, if bad enough, would allow exhaust gas to pressurize the crank-cases. The inlet being wornwould make idling erratic - more so once warmed up. Any oil mistthat had made its way up there would be added to the incoming fuel.

Yours, still thinking.

Ian.

Submitted by simon_amos on Fri, 19/03/2010

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Happier chappie this evening, Spoke to A Gaggs today who supplied the piston, I wanted to determine if the piston skirt length was critical, He had come across a similar problem with a Triumph twin that had been sleeved and bored, an incurable bad smoker, only remedy was a rebore to +020", this cure was unexplainable. He also mentioned that in some cases a honed bore can cause a smoking problem until the rings get a shine on the bore or a slight glaze, bingo last weekend after fitting the new compression rings I obtained a reasonably clean exhaust, the bore had achieved a slight glaze. Then monday I decided to fit a new oil ring, to further improve things I also gave the barrel a light hone, now I can understand why the smoking was back as bad as ever, the original state of the barrel was machined and honed. This evening I took the bike for a couple of mile run and by my return an almost clean exhaust, hopefully it will only get better, I'm going to leave well alone now. Incidently the oil I'm using is 20/50, may try Mono 40 next as my model 7 seems to thrive on it. So thankful to everyone for help and ideas, the solution is running it in. My wife is also pleased as the garage was passable without holding her breath.

Paul

Submitted by simon_amos on Sun, 28/03/2010

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Another point worth mentioning, Mike Pemberton at Pushrod Performance informed me that JP piston rings are radially thicker than the Hepolite rings. I have now looked at the thickness and it's quite right JP rings are 0.6mm thicker, I would imagine this will give them extra ring tension on the bore, also over 1mm on internal ID of the piston ring.

I then decided to start again, ordered a new standard JP piston from FW Thorntons who are most helpful, machined the Skirt to suit the 47 ES2 stroke and have fitted the piston with the new standard thicker JP ring set, extra expense but I now have peace of mind, a lovely clean exhaust and also gained a fair bit of knowledge of the behaviour of the ES2.

Just need some sunshine now to enjoy the bike.

Thanks and regards to all who have helped me with this problem.

Paul

Submitted by steven_lewis on Sun, 29/07/2012

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Hi, myexperiencewith the ES2 is to machine the piston oil groove to take a 3 piece oil ring. This has worked outstanding in 2 of my bikes to date.

Also, with running in a new engine, drain the sump prior to starting cold....this eliminates the flywheels throwing up the extra oil onto the piston. Cheers

Steve

 


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