PISTONS and RINGS TEIKOKU (JAPAN)
- Thread starter pierodn
- Start date
- Status
o0norton0o
VIP MEMBER
- Joined
- Apr 27, 2015
- Messages
- 2,000
Jim, It looks like these pistons come with the wire style circlips with the big tangs. Having been burned by that style of circlip popping out after a rebuild, I would hesitate to use this style circlip, but I would defer to your judgement.
- Joined
- May 28, 2003
- Messages
- 2,591
I have several of these mild pop-up high compression piston sets in various sizes. Nice and light, relatively...
The only problem is the ring pack is the early shallow type. They do have enough meat to cut the oil ring land for the deeper/late ring pack.
No further info on the pin circlip good/bad?
- Joined
- Dec 10, 2008
- Messages
- 7,253
I agree, I would not use that style clips in a Norton.
I am getting the feeling that these pistons may be very old stock. In that case I would likely defer to the JCC Emgo pistons. At least they fit a standard c-clip, even if the c-clip that comes with the JCC is junk, that easy to remedy.
Last edited:
Hi Jim.
These circlips seems to me are the same of GPM Gandini that i fit on my nortons.
Are they so bad too?
Thanks.
Piero
- Joined
- Dec 10, 2008
- Messages
- 7,253
They have a reputation for coming unseated and damaging the cylinder when they are revved hard.
o0norton0o
VIP MEMBER
- Joined
- Apr 27, 2015
- Messages
- 2,000
I've had a big tang wire circlip come out at speed, with a "POP" and a puff of blue/white smoke a few weeks after a rebuild. Certainly, anyone could say that I didn't get it seated properly, so it was my error, not the part that failed.
If you look at the circlip, there's no reason for the long tang pertruding toward the middle of the clip. I believe it acts like a bob weight when the piston changes direction and compresses the circlip. Of course this is just my speculation, based on my experience, but that's my single data point. I replaced them with the cut steel type and they've stayed in place for a few decades...
We do all that work to restore and improve a bike like a commando, then use the cheapest possible circlip which may be suspect in a place where part failure is catastrophic... No thanks, I'll spend the extra few dollars for 4 cut steel ones.
.
If you look at the circlip, there's no reason for the long tang pertruding toward the middle of the clip. I believe it acts like a bob weight when the piston changes direction and compresses the circlip. Of course this is just my speculation, based on my experience, but that's my single data point. I replaced them with the cut steel type and they've stayed in place for a few decades...
We do all that work to restore and improve a bike like a commando, then use the cheapest possible circlip which may be suspect in a place where part failure is catastrophic... No thanks, I'll spend the extra few dollars for 4 cut steel ones.
.
Hi.
I understand.
What do you think about the seager circlips (for sale from Andover?).
Thanks
Piero
o0norton0o
VIP MEMBER
- Joined
- Apr 27, 2015
- Messages
- 2,000
I replaced my wire circlips after my incident, with the seager circlips, and had no issues with any of them popping out for over 2 decades of riding. If you look at the circlips they are stamped out, and usually have a sharper edge on one side of the circlip. That sharper edge faces away from each piston's center.
Hi.
Sorry, if i have understood well the sharper edge goes on the external side and the convex side internal?.
Thank you.
Piero
Last edited:
- Joined
- Aug 14, 2009
- Messages
- 144
Never had problems with these wire-circlips on my GPM-pistons....i am no racer, but i treat my Commando not always nice 
i rather think that when they pop out than they are not installed correctly...
I also always doublecheck that the opened side of the circlip points to the piston crown...
i rather think that when they pop out than they are not installed correctly...
I also always doublecheck that the opened side of the circlip points to the piston crown...
- Joined
- May 7, 2005
- Messages
- 7,160
Correct sharp edge outwards so it resists being pushed outwards more than the rounded edge.
o0norton0o
VIP MEMBER
- Joined
- Apr 27, 2015
- Messages
- 2,000
Never had problems with these wire-circlips on my GPM-pistons....i am no racer, but i treat my Commando not always nice
i rather think that when they pop out than they are not installed correctly...
I also always doublecheck that the opened side of the circlip points to the piston crown...
I know that I can't rule out improper installation in my case. I rather think that anyone who examines these circlips sees that they are the worst choice of all possible choices. I realize that because they are already in your bike and have worked without issue for some time, that is evidence that they work fine. Of course I can't dispute your actual experience with these circlips given your result, but they are clearly the cheapest possible circlip you can buy... and given my experience with them I think the seager style circlips are a better choice and cheap insurance.
- Joined
- May 7, 2005
- Messages
- 7,160
But the circlip you use is also determined by the shape of the circlip groove in the piston, I got Cycle Craft pistons with wire circlips in the box but when I pressed blu tak into the groove and examined the impression found it was a square groove so ideal for seagar circlips which I then bought. If the groove had been round in profile I would have machined it square before fitting seagar clips.
- Joined
- Feb 10, 2009
- Messages
- 2,974
It would take a braver man than me to use this.
- Status
