Emgo pistons

Status
Not open for further replies.
Exactly F.E. that's my point.
Maybe the circlips were squeezed too tight during fitting or the cylinder bore was out of line causing the gudgeon pin pushing to one side? ...... ofcourse only skilful mechanics work on Nortons so it has to be the poor quality of the products!?
 
Last edited by a moderator:
Fast Eddie said:
But LOTS of pistons have round wire circlpks that don’t pop out.

So I’m still curious as to why the Emgo ones do?
Click to expand...

The US made JE pistons come with pins that are generously chamfered/beveled on the ends. When spring steel wire clips are used with this design the clips will not come out. When subjected to side forces the bevel of the pin end fits a little bit INSIDE THE PIT and actually attempts to force the clip to expand and makes it tighter in its recess.

The Hepolite/JCC pins lack enough OD chamfer on the end of the pin so side forces can push wire clip out of the groove and then you have a damaged cylinder wall. This is also why you see wear on flat clips and its why you have to be careful to orient the flat clips with the sharp side outward - if you install it the wrong way it can come loose.


See the end of the chamfered JE pin (right side) compared to the end of the Hepolite/JCC pin below.

Emgo pistons



There is a notch shown below at the pin boss so you can insert a small tool and remove the JE spring steel clips. The shorter pin is JE and is lighter than the Hepolite/JCC pin.

Emgo pistons
 
Last edited:
Emgo pistons
jseng1 said:
The US made JE pistons come with pins that are generously chamfered/beveled on the ends. When spring steel wire clips are used with this design the clips will not come out. When subjected to side forces the bevel of the pin end actually attempts to force the clip to expand and makes it tighter in its recess.

The Hepolite/JCC pins lack enough OD chamfer on the end of the pin so side forces can push wire clip out of the groove and then you have a damaged cylinder wall. This is also why you see wear on flat clips and its why you have to be careful to orient the flat clips with the sharp side outward - if you install it the wrong way it can come loose.


See the end of the chamfered JE pin (right side) compared to the end of the Hepolite/JCC pin below. The Hepolite pin was taper bored and that is why it is so thin. The JE pins can be taper bored up to the chamfer.
Click to expand...


That pin on the left looks sufficiently chamfered, to me.
The pins that came with my Harris and Hepolite versions of JCC pistons were certainly chamfered to effectively expand the clip, should the pins be pushed outwards against the clips. I tried it.
 
nortonspeed said:
Exactly F.E. that's my point.
Maybe the circlips were squeezed too tight during fitting or the cylinder bore was out of line causing the gudgeon pin pushing to one side? ...... ofcourse only skilful mechanics work on Nortons so it has to be the poor quality of the products!?
Click to expand...

Whether this was directed at my comment or not, I'll answer as if it was...

First of all, the problem with specifically MY wire circlips was the extra 'tang' which pertrudes inward on the circlip acts like a bobweight (like a centrifugal advance weight in a distributor) It's mass flexs the circlip when the piston goes up and down. This is why I believe the only wire ones that will work look like the one's in Jim Schmit's pictures. NO Tangs on them. Having extra mass at the greatest leverage point to flex the circlip is a mistake. The engineer who designed them is a dunce...

Secondly, I rebuilt that engine after the wire circlip debacle with cut steel circlips and haven't had any problems for 20 years of riding after that reassembly. I'm very conciencious. After my incident, I tore the top end down and brought it to the machinist. He told me the score was very light and mostly low on the cylinder wall. He said, assemble it with proper circlips (obviously) and if it smokes, then we'll go for the next bore size. 20 years,.... ZERO smoke and the new circlips stayed put.

Third, You can second guess my skill set all you want. Maybe I crushed the circlip to install it... If you read my first post, you'll see that I used the shitty wire circlips which I got with the pistons, but I was skeptical when I saw them and only used them because I figured the supplier knew better than I,... which he did not..
 
I had trouble with these pistons as well.
I acquired my 72 as a basket case more than 20 years ago, about 80% complete. carefully took it apart, by the books, not much internet then. The shop in CA that sold me the bike provided me with EMGO pistons and Hastings rings. I put it all together by the book, and fit the pistons as they were factory marked L+R, as is sitting on the bike.

after getting it all together, and going thru the ring seat/break-in miles, it started to smoke real bad. So It took it all down again, and saw that, by valve marks in the tops of the pistons, the L+R marks on the piston tops were 180º opposite! So of course I switched them around, put it all together again, and the smoking was just as bad. Concluding that the first, piston-opposite assembly had damaged my valves, I took it down again, and replaced my new valves, guides, and seals, with newer ones... this is getting expensive!

Upon re-assembly, the bike ran well (mikuni and boyer helped!) with almost no smoke and lotsa power... for about 8K miles. Then last year, I saw oil gushing out of a crack in the cylinder base flange, and took it down again, only to find that crack, and a crack in the cylinder wall.... grrr can't say for sure but I think the original piston mis-mark may be what screwed the pooch.

Looking at another $1000 or more in repairs, three weeks ago I sent EMGO an email, describing the above situation, asking for a new, correct pair of pistons. To this date, NO REPLY. They obviously do not stand by their products, some of which products that really involve life and death issues.
 
DonOR said:
I had trouble with these pistons as well.
I acquired my 72 as a basket case more than 20 years ago, about 80% complete. carefully took it apart, by the books, not much internet then. The shop in CA that sold me the bike provided me with EMGO pistons and Hastings rings. I put it all together by the book, and fit the pistons as they were factory marked L+R, as is sitting on the bike.

after getting it all together, and going thru the ring seat/break-in miles, it started to smoke real bad. So It took it all down again, and saw that, by valve marks in the tops of the pistons, the L+R marks on the piston tops were 180º opposite! So of course I switched them around, put it all together again, and the smoking was just as bad. Concluding that the first, piston-opposite assembly had damaged my valves, I took it down again, and replaced my new valves, guides, and seals, with newer ones... this is getting expensive!

Upon re-assembly, the bike ran well (mikuni and boyer helped!) with almost no smoke and lotsa power... for about 8K miles. Then last year, I saw oil gushing out of a crack in the cylinder base flange, and took it down again, only to find that crack, and a crack in the cylinder wall.... grrr can't say for sure but I think the original piston mis-mark may be what screwed the pooch.

Looking at another $1000 or more in repairs, three weeks ago I sent EMGO an email, describing the above situation, asking for a new, correct pair of pistons. To this date, NO REPLY. They obviously do not stand by their products, some of which products that really involve life and death issues.
Click to expand...

You fitted the pistons backwards, fixed that and did 8,000 miles and then the cylinder broke. Have I got that right?
 
DonOR said:
I had trouble with these pistons as well.
I acquired my 72 as a basket case more than 20 years ago, about 80% complete. carefully took it apart, by the books, not much internet then. The shop in CA that sold me the bike provided me with EMGO pistons and Hastings rings. I put it all together by the book, and fit the pistons as they were factory marked L+R, as is sitting on the bike.

after getting it all together, and going thru the ring seat/break-in miles, it started to smoke real bad. So It took it all down again, and saw that, by valve marks in the tops of the pistons, the L+R marks on the piston tops were 180º opposite! So of course I switched them around, put it all together again, and the smoking was just as bad. Concluding that the first, piston-opposite assembly had damaged my valves, I took it down again, and replaced my new valves, guides, and seals, with newer ones... this is getting expensive!

Upon re-assembly, the bike ran well (mikuni and boyer helped!) with almost no smoke and lotsa power... for about 8K miles. Then last year, I saw oil gushing out of a crack in the cylinder base flange, and took it down again, only to find that crack, and a crack in the cylinder wall.... grrr can't say for sure but I think the original piston mis-mark may be what screwed the pooch.

Looking at another $1000 or more in repairs, three weeks ago I sent EMGO an email, describing the above situation, asking for a new, correct pair of pistons. To this date, NO REPLY. They obviously do not stand by their products, some of which products that really involve life and death issues.
Click to expand...

I can’t see how the piston design, or the fact you fitted them backwards, could have led to the barrel cracking. That’s a separate (and not unknown) issue surely?
 
well, I fitted pistons as they were factory marked, L+R ... but not sure how long of a time the cylinder had been failing for, it could have been a long term fault that anything may have caused, but the incorrect piston marks are a serious manufacturing defect that cost me a second head rebuild, no?
 
If they stamped a pair of pistons wrong, it seems likely they would have stamped many more pistons wrong that day.
 
DonOR said:
well, I fitted pistons as they were factory marked, L+R ... but not sure how long of a time the cylinder had been failing for, it could have been a long term fault that anything may have caused, but the incorrect piston marks are a serious manufacturing defect that cost me a second head rebuild, no?
Click to expand...

Oh I see. It’s probably obvious to you what you meant to say, but I did not conclude from your post that the pistons were incorrectly marked, I concluded that you simply assembled them incorrectly!

Just a thought, but perhaps Emgo concluded the same? And perhaps that’s why they didn’t reply?
 
yes, and I fuked up by installing them as factory marked. If I paid somebody to do the work, and they installed them as marked, where would I be then?
 
Well they certainly look incorrectly marked in your previous post!

I still say this has no direct correlation to your cracked barrel though. If the barrel was good, it would take a heck of a lot of force to crack it. The kind of force that would totally destroy valves and bury them into the head.

As to claiming anything piston supplier, I suspect they will have covered their ass by saying something like ‘check all clearances prior to assembly’.

Might not seem ‘fair’ but I would very much doubt you have any legal case against them.
 
I recall using Emgo pistols that were incorrectly marked, reversed. This was in 1999. I did see it before I put the head on. I assumed whoever marked the pistons was severely dyslexic.
 
ok, thanks, I'm sure you would know, and the barrel fault is probably another thing, and the wasted valves and guides were some time ago.
mistakes happen, and though I believe ‘check all clearances’ should be the manufactures thing, life is not fair...
but as a businessman of almost 40 years, I can honestly say that anything I did wrong, I made right. No matter what the cost. not the case with EMGO.
 
A businessman who operates on the principle of fairness is, sadly, a rare thing these days IMHO. And the bigger the business, the rarer it becomes!
 
worntorn said:
This idea that all US residing British bike owners on this forum must purchase only US made parts must be coming from some sort of splinter fringe group.

Glen
Click to expand...

But Glen there are also good parts for our Nortons made in Europe not ? Where the people live better than in ASIA.
In France parts Emgo, Wassel, Spark etc. .. is less and less welcome,it is against manners or copy.
 
Last edited:
Triton thrasher - the piece of clip wire in the photo below is too close to the flat of the JCC/Hepolite pin - it could push out the clip. There is not enough champer on the pin to be safe. And the fact is that JCC clips are coming loose. This does not happen with JE pistons/pins/clips.

oOnortonOo is right - the tangs on the JCC/hepolite clips are an accident waiting to happen. And they would rub on the flat of a pin even if the pin was chamfered - the pin would push out the clip at the tangs - then the entire clip would come out and eat away at the cylinder wall.


Emgo pistons


Go back and look at oOnortonOo photo of Emgo (?) wire clips on the previous page. You can see that the top clip is worn flat on one side from rubbing against the pin.
 
Last edited:
Status
Not open for further replies.
Back
Top