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ES2 Con rod bearing rocking movement

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After having issues with oil getting into the combustion chamber, and following another thread about engine problems, today the barrel came off my ES2 to check that the piston rings were the correct way round. I can't see a difference on either edge of the rings, so can't tell if there is a right or wrong way round.

Anyway, that's now become the least of my issues. My main concern now is that the bearing rollers on the big end side of the con rod don't feel right at all to me when I move the con rod from side to side. There's a lot of movement that I just don't remember being there when I put it together just a few months back. I understand that there will be some sideways movement, but I didnât expect the rocking from side to side that I'm feeling.

I'm posting this in the slim hope that I'm wrong and that someone can tell me that the movement I can see is normal and that I won't need to pull the fly wheels apart again to put new bearings in. You can see a short video of the issue on this youtube link:

https://youtu.be/In0Z5H6dCqE

One of the main things I don't understand is that the engine sounded really great and really tight when running (Itâs done about 100 miles so far since it was put back together) and surely if the race of bearings were shot, the engine would have sounded awful when running.

Any advice from those with experience of these Norton singles would be appreciated.

Thanks

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Hi Aled,

Just had a look at your youtube clip and the side-play on the big-end looks quite a lot, but the main test is to make sure the flywheels can't move with them at top dead centre and try to lift and push down the con-rod keeping the rod vertical and feel for any movement. The ES2/16H big-end bearing is a poor design and has the double row of rollers crowded together with only half an inch in width and no cage and this allows the con-rod to move side to side. What work did you do to the big-end when you put the engine together, was it a new bearing or just new rollers or did you use the old one?

Regards, Richard.

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Hi Aled

I understand you are more worried about the rocking movement of the con rod rather than the side way movement. Could this be due to the barrel shape rollers in the big end? When the piston is in the barrel this may not be an issue. Perhaps the only worry here would be if you have up and down movement. I don't know a lot about this type of bearing hopefully other will be more helpful.

Regards Peter

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The books say not to worry too much about rocking side to side but as Richard says, feel for any up and down play when pulling and pushing the con rod. There should not be any. What 'no movement' precisely means isn't precisely clear...

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When I put the engine together, I used a new con rod with new big end bearing, but used the existing rollers for two reasons, firstly, they looked in really good condition (not that it's easy to tell if they are worn of course), and secondly, the rollers were one row of 1/4 x /1/2 rather than a double row of 1/4 x 1/4 which I thought was better, and I couldn't find replacements that size.

It might be that a single row somehow allows for more of a rocking movement than if I'd used a double row.

I'll go away and have another look at trying to isolate the up and down movement only to see if there is any.

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When I took my 46 Model 18 apart, it also had a single row of rollers. It also had excessive side play.

This was aggravated by the fact that there was a ridge that had formed between the two rows of 1/4 X1/4 rollers.

This was very excessive and noticeable, in my case.

When you state new big end, do you mean purchased new or ?

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Hi aled, looking at your u tube clip i think you have a problem. Think you need to fit a new big end assy. why did you use the old rollers. If you had a new big end assy it comes with rollers , yes? Did you mic up the rollers that you fitted. If they are more than 0.001 thou undersize then they should have been replaced. 'Simply bearings' sell loose rollers. Does sound odd though as it has worn so quickly. Think you need to strip it unfortunately.If i remember correctly i think ive read that side to side play shouldnt be much over 0.015 thou. The rollers are not barrel shaped and should read 0.250 with a micrometer. hope thats of some use. Hope your crank pin and outer race are still ok. Regards, colin eggleton.

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Hi Aled,

When you get a new big-end bearing all parts should be matched by the manufacturer for best fit at the factory and supplied as a set. With modern CNC machines this is not so much of an issue, but back in the day it was essential. The rollers are usually a very precise size but the crank-pin and the outer ring can vary, hence the need for selective fit. When you are working with this type of bearing you will need a micrometer as you will need to measure accurately to 0.0005". Long rollers are good if they run in a cage but when they are running against each other you get a lateral skew and they scuff more than shorter ones which can wear the outer edges away more than the centre. If there is no up and down play I would be happy to use "as is" and you should get a few thousand miles out of it if you change the oil regularly.

Regards, Richard.

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Hi Aled, I think you had better start again as that rocking I see is not correct for a new assembly. Side slip, yes, but not that excessive rock. If the pin has any central ridge on the track, the one piece rollers will be running on that, promoting rapid wear, also, the uncaged long rollers, as said above, are bad news. Stick to tworows of 1/4"x 1/4" as per original manufacture. I am surprised anybody would fit second hand rollersof an unknown quality back in after going so far in a rebuild. Correct rollers are readily available. 'Simply Bearings' is one supplier.

Best of luck,

Paul

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I decided that the rocking movement in the con rod was ok for now as there was no up and down movement. I'll run it like this over the summer, and strip it down again come the winter if I feel it's getting any worse. I also took the piston rings off and found that the middle one had top written on it, where the other rings had no markings. Watched Pemberton's DVD where he only has top written one one ring, and he says that (unsurprisingly) it should be placed in the top groove. Even though I couldn't see any difference in the rings at all, I swapped the top and middle one over, put the engine back together, and all the smoking has stopped... It's hard to believe that two rings that look identical being in the wrong order could have been the cause of so much oil getting into the chamber, but I guess it said TOP on one for a reason. Thanks for all the advice everyone, I'm sure I'll be back for some more advice soon.

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Some 3 years ago Aled Corps wrote about his rocking conrod. My ES2 has now caught it. Aled concluded he would leave it as is and see how it went. How did it go, Aled? I shall be putting the top end back on in a week or two and need to know whether I have to delve into the bowels of the crankcase. Like you, I have no discernible up/down movement but a definite sideways "rock".

Problem is, I was always a bit of a "Rocker"!

George

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.. in fact every big single with a roller big end that I've owned has had substantial sideways (and rocking) motion. I have to confess that one or two have also had just perceptible up and down (not my current ES2) and have run perfectly well like that.

I do think that it's easy to go overboard and seek perfection whereas I prefer to just ride it if it's mechanically quiet and performs well. Similarly I wouldn't do a rebore until the wear was significant (Edgar Franks suggested .007" wear was time to take action) so if it's 3 or 4 thou I'm happy - plus it saves all that tedious running in.

The 350 Sunbeam I restored a few years ago had been rebored far too tight by a previous owner and tightened up when given any work. A couple of thou honed out made it far better with no loss of compression or oil burning.

Purists will probably throw up their hands in horror but back in the 1970s when my bike was my only transport and I had no money,changing bits that worked perfectly adequately would have been out of the question.

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Ian,

you say "changing bits that worked perfectly adequately would have been out of the question."

I apply that rule to my bikes today too! 

What was the old saying - "if it 'aint broke, don't fix it"?

Regards,

George

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Just to put this one to bed, I put the query to Mike Pemberton (Pushrod Performance) who answered:

When I fit a new Big-End bearing there has to be 0.001” of clearance or the bearing will self destruct. You can just about move the rod around 1/8” either way. If the rod is almost touching the flywheels then I would say it is on its last legs!

So there you have it. In my case the movement is quite normal so great relief - particularly in my wallet!

George

 

 

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