I have Ross Racing rings to put in a Laverda. Ok cylinders bored @ 8/100ths. Rings 2 & top pregapped gapped@ 33mm. Ok the oil expander ring edge when placed in piston will stick out slightly from the circumference of the piston. So my guess is it also is Ok. Rails are on the inside lip step...So I guess it is preset? 2nd & top ring are @ 33mm gap but the rails when on the oil expander ring have a much larger gap. Called Ross they said it should be Ok. Just want to be sure...
oil expander rings Laverda
- Thread starter Evan
- Start date
I fitted my Ross Racing pistons yesterday and the oil ring did give me some concern.
The website is useful https://www.rosspistons.com/wp-content/uploads/2016/08/Ring-Installation.pdf
Essentially, the gaps dont overlap and the ends are fitted pointing downwards, the rings are fitted with the gaps 90 degrees away from the oil ring gap and 180 degrees apart from each other.
The home made ring compressors worked a treat
The website is useful https://www.rosspistons.com/wp-content/uploads/2016/08/Ring-Installation.pdf
Essentially, the gaps dont overlap and the ends are fitted pointing downwards, the rings are fitted with the gaps 90 degrees away from the oil ring gap and 180 degrees apart from each other.
The home made ring compressors worked a treat
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Dellortoman
Hero member
- Location
- Tasmania, Australia
Evan said:
33 mm gap?
chrisk
Hero member
- Location
- Brisbane, Australia
Paul Marx said:
Me too
Ofcourse the expander ring is set back by the rails when rails are set top and bottom. But w/ the rails on... the expander does stick out around the circumference. So I guess expander ring is supposed to stick out beyond the piston circumference just inside the rails. I was thinking the expander ring may be weak this way and prone to break. And the rails are far beyond 33mm gap. So put it on anyway???
chrisk
Hero member
- Location
- Brisbane, Australia
Dellortoman said:33 mm gap?
What is this 33mm gap everyone is talking about? Don't slam it back together yet, something ain't right.
Dellortoman
Hero member
- Location
- Tasmania, Australia
Your description is a little vague to me, but it sounds as if the corrugated separator that goes between the upper and lower oil scraper rings has a greater OD than the scraper rings themselves. That doesn't sound right to me.
The upper and lower oil rings should have a larger OD than the cylinder bore, so their spring pressure forces them against the cylinder wall (in a similar manner to the compression rings). The oil ring separator (aka: support rail) should be wound tighter with its tension inward so it sits against the back of the oil ring groove. If your separator is loose on the piston, it will rub against the cylinder wall rather than sit back against the piston. I'm surprised the Ross people said that's OK. Perhaps they misunderstood your question. I'd check with them again if I were you. Send them a photo to show exactly what you're talking about.
None of the ring gaps should be 33mm. That would mean the ring doesn't go all the way around the piston! It must be 0.33mm (which sounds about right for the bore size) so you're only out by a factor of 100.
End gap is only important for the two compression rings, although the 2nd ring may have a slightly smaller end gap because it doesn't get as hot as the top ring. The end gap is not critical for the oil ring. Don't worry if it's more than 0.33mm.
The upper and lower oil rings should have a larger OD than the cylinder bore, so their spring pressure forces them against the cylinder wall (in a similar manner to the compression rings). The oil ring separator (aka: support rail) should be wound tighter with its tension inward so it sits against the back of the oil ring groove. If your separator is loose on the piston, it will rub against the cylinder wall rather than sit back against the piston. I'm surprised the Ross people said that's OK. Perhaps they misunderstood your question. I'd check with them again if I were you. Send them a photo to show exactly what you're talking about.
None of the ring gaps should be 33mm. That would mean the ring doesn't go all the way around the piston! It must be 0.33mm (which sounds about right for the bore size) so you're only out by a factor of 100.
End gap is only important for the two compression rings, although the 2nd ring may have a slightly smaller end gap because it doesn't get as hot as the top ring. The end gap is not critical for the oil ring. Don't worry if it's more than 0.33mm.
Evan said:
This was the critical point for me 'the rings are fitted with the gaps 90 degrees away from the oil ring(expander) gap and 180 degrees apart from each other.'
If the ring gaps line up with the expander gap there is interference that makes the rings sit proud.
michipons
Hero member
- Location
- Palma de Mallorca
Did you get ross rings or total seal rings?
I recently bought ross pistons and were delivered with total seal rings, that REQUIRE to make the ring gap, since they are overlaping (top and second) the oil ring is fine.
The topic is still fresh, I uploaded some photos of the ross explanations.
By the way, how did you do the home made rings compressor? What is the material that compresses?
Regards,
Miguel
I recently bought ross pistons and were delivered with total seal rings, that REQUIRE to make the ring gap, since they are overlaping (top and second) the oil ring is fine.
The topic is still fresh, I uploaded some photos of the ross explanations.
By the way, how did you do the home made rings compressor? What is the material that compresses?
Regards,
Miguel
Gravelroad
Hero member
- Location
- Central Europe
michipons said:
Gravelroad
Hero member
- Location
- Central Europe
You talking about the 794U-3 type, Gerald, right?
https://www.autodoc.de/hazet/10217063?utm_source=priceagregator&utm_medium=nextag_atd_de
A set of 2 is the nicest thing I can imagine for bringing the pistons into the barrel of a 180 triple. (bigthumb)
https://www.autodoc.de/hazet/10217063?utm_source=priceagregator&utm_medium=nextag_atd_de
A set of 2 is the nicest thing I can imagine for bringing the pistons into the barrel of a 180 triple. (bigthumb)
piranha-bro2
Hero member
- Location
- Melbourne
Unless I was doing a motor a week, I couldn't justify anything so extravagant! Some thin sheet with a few bevels in the right places and a hose clamp will do me. I've actually done loads of SFs with no ring compressor and only broken one 2nd ring over many decades. Triple is a tad trickier.