piston circlip designs

[timebombprod]

the circlips my bore kit came with are a different design than my OEM ones and i was wondering if i should run a certain one, the OEM is a simple open ring shape and the bore kit circlips have more of a 2 stroke design to them, having one end bent in a bit. somebody whos been helping me out with my rebuild said the bore kit circlips are a design that tend to fall out and i just wanted to see your guys opinions on them.

 

[zed1015]

Never had any type fall out that have been correctly fitted.
Circlips that come adrift have usually been reused and distorted or the wrong size from the get go..

 

[rphillips]

I'd just pick the easiest to install.

 

[Grimly]

I'd use the ones that come with the kit. I suspect they'd know what they're doing.
Like said, never re-use circlips and be careful with them in fitting.

 

[timebombprod]

Okay Im gonna use the ones that came with the kit, are there any disadvantages to any circlip design?

 

[rphillips]

Back in the day, some piston kits came with nylon buttons instead if spring clips. Just stick a button in on both ends of the pin & the button took up the space between the cyl. wall & end of pin, no way for pin to slide out. Anybody still use them??

 

[Grimly]

Okay Im gonna use the ones that came with the kit, are there any disadvantages to any circlip design?

The older circlips with two eyes on them had more mass and were sometimes prone to leaving their grooves at high revs.
However, I've never known it happen on an engine that was rebuilt properly. I suspect the tales of woe came from victims of re-using old ones or buying (or paying for an engine rebuild) by some eejit who cut corners.

 

[eil]

If both sets are brand-new, then either one is fine. I would use whichever ones were easier or more fool-proof (for me) to install.

 

[zed1015]

Back in the day, some piston kits came with nylon buttons instead if spring clips. Just stick a button in on both ends of the pin & the button took up the space between the cyl. wall & end of pin, no way for pin to slide out. Anybody still use them??

Yes! MTC Pistons and a few others use Teflon buttons.
Ok for race bikes that get fairly regular inspections and we use them on the drag bike but they can polish a strip on the bores on higher mileage engines and wear down to nothing allowing the pin to gouge the liner so i only use circlips for the road motors.

 

[Rijko]

I'd use the ones that come with the kit. I suspect they'd know what they're doing..

+1.

OEM grooves in the pistons and corresponding circlips are not always the same size as other manufacturers.
So use the clips that came with the kit or make sure it's ok to use OEM clips.

Differences may be subtle.
Like Yoshimura has the grooves in the pistons closer together than OEM on some bikes, so the OEM wrist pins are a fraction too long and need Yoshi ones or access to a lathe to shorten the OEM pins a couple of tenths.

Baffling at first, because you can insert the wrist pin and see the circlip groove looking perfect.. except the circlip won't click into the groove.

Dangerous if not noticed, that's a non-seated clip just waiting to cause damage.

 

[Nessism]

Circlips with the little hook bend on one end are easier to remove. I agree with just using with what comes with the kit.

 

[timebombprod]

Here's my bore kit circlip next to the piston, is there a certain way the circlip sits relative to the groove for the circlip? Like if the bent end should be opposite of where the groove in the piston is open

 

[Grimly]

Gap to the bottom...
https://www.engineaustralia.com.au/wp-content/uploads/2018/04/SB010.pdf

 

[timebombprod]

okay sweet, thanks!