O.S. 52 Surpass idling problem
09-03-2005 | 11:36 AM
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From: Caledonia, IL
O.S. 52 Surpass idling problem
Somehow, I remember a specific forum on engine problems on RCU, but can't seem to find it now, so I'm putting the question here.
I have a nearly new (about 1/2 gal. run thru) O.S. Surpass (4 cycle) 52 engine on my deHavilland Beaver. The engine runs powerfully and is very adequate on this 6' w.s. Beaver. I'm having trouble getting the engine to idle properly tho. I've adjusted the h.s. needle leaner since the initial break-in, and it runs well at full throttle vertically as well as when held horizontally with no rise or fall in RPM's. When the engine is idling tho, even if I've trimmed for a little higher idle speed initially, after 10 or 15 seconds, the engine will slow down and sometimes sputter to a stop. I also find that after starting, with the throttle opened to produce maybe 5000 RPM, when taking the ignitor off the glo plug, the engine will slow down considerably. The latter condition to my understanding, tells me that the mixture is too rich, but if I lean the H.S. needle much more, the engine appears to run lean and smells like it's overheating. I've tweaked the idle mixture screw about 1/4 turn to the lean side, but the engine continues to have this problem. Here's a strange, tho: While taxiing back to the pits yesterday, the engine was IDLING a little fast, and it took some lucky manuvering to get the plane past the maze of fence openings without striking one of the wings before I was able to slow the engine down by pressing the kill button, which by the way, only slowed the engine enough to stop it's forward movement! Maybe someone with some 4-cycle experience can help me out here, as the plane it's on was a kit and took considerable time to build. I sure don't want to lose it in a dead-stick landing situation way over a corn field.
Jackster
I have a nearly new (about 1/2 gal. run thru) O.S. Surpass (4 cycle) 52 engine on my deHavilland Beaver. The engine runs powerfully and is very adequate on this 6' w.s. Beaver. I'm having trouble getting the engine to idle properly tho. I've adjusted the h.s. needle leaner since the initial break-in, and it runs well at full throttle vertically as well as when held horizontally with no rise or fall in RPM's. When the engine is idling tho, even if I've trimmed for a little higher idle speed initially, after 10 or 15 seconds, the engine will slow down and sometimes sputter to a stop. I also find that after starting, with the throttle opened to produce maybe 5000 RPM, when taking the ignitor off the glo plug, the engine will slow down considerably. The latter condition to my understanding, tells me that the mixture is too rich, but if I lean the H.S. needle much more, the engine appears to run lean and smells like it's overheating. I've tweaked the idle mixture screw about 1/4 turn to the lean side, but the engine continues to have this problem. Here's a strange, tho: While taxiing back to the pits yesterday, the engine was IDLING a little fast, and it took some lucky manuvering to get the plane past the maze of fence openings without striking one of the wings before I was able to slow the engine down by pressing the kill button, which by the way, only slowed the engine enough to stop it's forward movement! Maybe someone with some 4-cycle experience can help me out here, as the plane it's on was a kit and took considerable time to build. I sure don't want to lose it in a dead-stick landing situation way over a corn field.
Jackster
09-03-2005 | 05:01 PM
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From: kerrville, TX
RE: O.S. 52 Surpass idling problem
jackster,
I've had a couple .52s and they are super little engines. They have also been very easy handling with one exception....they HATE any plug but OS four stroke plugs. Have not found another variety that provided good running characteristics at both top end and idle...at the same time. So, if you can tune for top-end but loose reliable idle...or vice versa you might want to switch to an OS F plug. That is if you aren't currently running same. BTW, plugs can be born funky, so it might be a good idea to try another plug. Again...if you haven't done that already.
I generally run 5% two-stroke fuel for the extra oil...sometimes 10% two-stroke. Needles set a little on the rich side.
I've had a couple .52s and they are super little engines. They have also been very easy handling with one exception....they HATE any plug but OS four stroke plugs. Have not found another variety that provided good running characteristics at both top end and idle...at the same time. So, if you can tune for top-end but loose reliable idle...or vice versa you might want to switch to an OS F plug. That is if you aren't currently running same. BTW, plugs can be born funky, so it might be a good idea to try another plug. Again...if you haven't done that already.
I generally run 5% two-stroke fuel for the extra oil...sometimes 10% two-stroke. Needles set a little on the rich side.
