Board index Flathead Power-Technical Questions, Answers, and Suggestions Big Twin Flatties Question about oil control piston rings

Question about oil control piston rings

Post Wed Sep 14, 2016 12:12 pm

Posts: 22
Location: somewhere near Stratford, Ontario Canada

Hi, I have a 74" UL with re-sleeved cylinders stock bore, with brand new NOS HD pistons. The rings have a one piece solid oil control ring with no windows. My machinist wants me to go to a Hastings three piece ring with the corrugated center oil ring for better oil scraping and an easier time for the oil to find it's way in to the windows in the piston. Is there any reason not to follow his advice and keep the cast oil ring, or is an updated modern Hasting style oil ring a better choice? Thanks.


Posts: 118
Go with the upgraded rings. the old oil rings are 1930 tech. the 1950s type work much better.


Posts: 120
a modern cast strutted piston using shovelhead type rings would be a big improvement. my 39 U consumes so little that i need not add any between oil changes, these pistons are readily available too.


Posts: 377
I use hastings rings myself. Company wise we sell hastingrings and OEM rings. From none we ever have any real issues.

There are theories of how the thin oilscraping rings could cause more pressure on the cylinder and thus eating away the walls faster, but as far as I know this has never been empirically proven.

There are clearly people that are Pro old type rings and people that are pro hastings type rings. I suppose in the same way that there are people that are pro multigrade and anti multigrade oil. It depends what features you give more importance.


Posts: 120
i have repop cylinders with 45k miles on them. one is standard bore and the other is .10 os due to a scratch from a bit of trash in the wrist pin. the hasting rings have been very kind to my bores. i have honed the cylinders twice for new rings since the top end needed to come off to address valve cover leaks. i do run multi weight 20/50 synthetic with a 1/4 quart of marvel mystery oil. i ride this bike every day i can and take vacation trips of 1500 to 3000 miles routinely for the past four seasons. wish you the best with your U model, set up right they are a rock solid riide.


Posts: 22
Location: somewhere near Stratford, Ontario Canada

Another piece of info is that the baffle plates in the cylinder holes have been removed. Would that make the 3 piece ring a better choice?


Posts: 377
scaryguy wrote:
Another piece of info is that the baffle plates in the cylinder holes have been removed. Would that make the 3 piece ring a better choice?


You better get those plates back in, or you will get a jammed engine eventually. The baffle plates cause extra oil to get sucked into the cilinders!


Posts: 1193
Location: Ojo Caliente,NM,USA
Samsup,
I've run lots of old bikes without them without any problem. I think they were necessary for the total loss systems but once they started pumping oil into the crank they served no positive function. You gotta cut them out of a stroker and they have much higher piston speed.
Dusty


Posts: 3316
Location: Central Illinois, USA
My experience echoes Dusty,

Welding in baffles usually causes more distortion than they are worth.

....Cotten

don User avatar

Posts: 579
Location: Spokane WA USA
"Another piece of info is that the baffle plates in the cylinder holes have been removed. Would that make the 3 piece ring a better choice?"


Do a SEARCH here, "Baffles Oiling" Gets 36 responses.
don


Posts: 2717
Location: Los Angeles, CA
don wrote:
"Another piece of info is that the baffle plates in the cylinder holes have been removed. Would that make the 3 piece ring a better choice?"


Do a SEARCH here, "Baffles Oiling" Gets 36 responses.
don



That would make it the only choice.


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