US 41cc Engine problem
04-25-2007, 09:30 PM
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US 41cc Engine problem
Hi guys, I hope someone can help me out here. I have a US 41cc gasoline engine mounted to the new GP Aeromaster bipe. The engine has a spring starter and is brand new(old stock). I purchased it from a member here on RCU a couple years ago. My question is why is there so much runout on the crankshaft and if this is common on these engines. I can hold the prop in the 12-6 o'clock postion and move the top of the prop at least 1/64"-1/32" back while pressing on the top blade with my hand. I do know that it starts very easily and runs great with no adjustments to the carb whatsoever. I have also noticed that it seems to run very smooth until 3/4 throttle, then the plane shook so badly it loosened the 4-40 socket head cap screws holding the N struts in place to the point that I lost 4 of them along with the lock washers and flat washers for the N struts. By the way this engine is hard mounted to the firewall. I appreciate any help someone can give me. Thanks, Ben
04-25-2007, 09:48 PM
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RE: US 41cc Engine problem
You probably got one of the in between US41s sold by Tower a few years ago...The taper in the flywheels was cast, not machined, and the hubs were drilled and tapped off center..Some of the hubs unscrewed the first time someone put a starter on the prop...Some of the cylinder castings were bad enough that the pulse hole under the carb block leaked....
The US engines have roller bearings on the crank and are not very tight when new...
I had good results straightening out the flywheels and making hubs that had no runout...
Anyone who remembers the old RC Online forum might remember the open letter I put on there about these engines
The instructions that came with the engines said all were run prior to shipping..Impossible, the leaky pulse and loose hubs would have shown up there...I think Tower was in denial, I don't know how many they got back to repair, if any.....
The problems disappeared after a while, maybe someone saw the light...[8D]
The US engines have roller bearings on the crank and are not very tight when new...
I had good results straightening out the flywheels and making hubs that had no runout...
Anyone who remembers the old RC Online forum might remember the open letter I put on there about these engines
The instructions that came with the engines said all were run prior to shipping..Impossible, the leaky pulse and loose hubs would have shown up there...I think Tower was in denial, I don't know how many they got back to repair, if any.....
The problems disappeared after a while, maybe someone saw the light...[8D]
04-26-2007, 12:55 AM
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RE: US 41cc Engine problem
Thanks for the quick reply Ralph. So in essence, I have a boat anchor mounted on the plane. I was really wanting to maiden the plane this week, oh well. Thanks again for the quick reply. Ben
04-26-2007, 01:25 AM
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RE: US 41cc Engine problem
The crank and flywheel are easily fixed......There are lots of US 41s out there.....
Take the spark plug out and watch the hub as you rotate the crank, the bad ones were easy to see.....
Take the spark plug out and watch the hub as you rotate the crank, the bad ones were easy to see.....
04-26-2007, 06:40 PM
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RE: US 41cc Engine problem
Hi Ralph, Can you point me in the direction to get this fixed? Can you do it for me or refer me to someone who can? What did you mean when you said the roller bearings weren't tight when new? Was the workmanship that shoddy on these engines? I have a friend who once swore they were as well built and lasted as long as any other competitors engine if not longer. Thanks again for the help. Ben
11-27-2009, 02:22 PM
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RE: US 41cc Engine problem
Hi all, i have us 41 cc engine its new. i have take from my frind.he buy it from tower before approxmatly 6 years.i have fitting the engine on my top flight p-51 mustang.
i dont know how this engine work. i see a video in youtube for the enigine working.the guy only turning the engine and its running from first trying.
i have going and do the same thing with my engine but its hard to start and when its start its off fast only running few second , i have try too many times but the same problem i have.any one can help me and telling me how its this engine working?
i have DA 50 and DL but its not the same steps to work this us 41cc engine.
i dont know how this engine work. i see a video in youtube for the enigine working.the guy only turning the engine and its running from first trying.
i have going and do the same thing with my engine but its hard to start and when its start its off fast only running few second , i have try too many times but the same problem i have.any one can help me and telling me how its this engine working?
i have DA 50 and DL but its not the same steps to work this us 41cc engine.
11-27-2009, 02:54 PM
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RE: US 41cc Engine problem
Should work pretty much the same. Set the carb needles to 1-1/2 turns open to get the engine started. Adjust the needles for best performance after the engine warms up. It's possible that the carb diaphragm and check valve gasket need to be replaced due to old age. Prolly a good idea anyway since ethanol is now used in gas. The carb you have was probably made before the change to ethanol resistant diaphragm material.
11-27-2009, 08:41 PM
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RE: US 41cc Engine problem
ORIGINAL: teufelhund
Hi guys, I hope someone can help me out here. I have a US 41cc gasoline engine mounted to the new GP Aeromaster bipe. The engine has a spring starter and is brand new(old stock). I purchased it from a member here on RCU a couple years ago. My question is why is there so much runout on the crankshaft and if this is common on these engines. I can hold the prop in the 12-6 o'clock postion and move the top of the prop at least 1/64''-1/32'' back while pressing on the top blade with my hand. I do know that it starts very easily and runs great with no adjustments to the carb whatsoever. I have also noticed that it seems to run very smooth until 3/4 throttle, then the plane shook so badly it loosened the 4-40 socket head cap screws holding the N struts in place to the point that I lost 4 of them along with the lock washers and flat washers for the N struts. By the way this engine is hard mounted to the firewall. I appreciate any help someone can give me. Thanks, Ben
Hi guys, I hope someone can help me out here. I have a US 41cc gasoline engine mounted to the new GP Aeromaster bipe. The engine has a spring starter and is brand new(old stock). I purchased it from a member here on RCU a couple years ago. My question is why is there so much runout on the crankshaft and if this is common on these engines. I can hold the prop in the 12-6 o'clock postion and move the top of the prop at least 1/64''-1/32'' back while pressing on the top blade with my hand. I do know that it starts very easily and runs great with no adjustments to the carb whatsoever. I have also noticed that it seems to run very smooth until 3/4 throttle, then the plane shook so badly it loosened the 4-40 socket head cap screws holding the N struts in place to the point that I lost 4 of them along with the lock washers and flat washers for the N struts. By the way this engine is hard mounted to the firewall. I appreciate any help someone can give me. Thanks, Ben
I had a 41 on my TFGS P-51.. Not a powerhouse, but did fly the plane acceptably....until.....flying straight and level when the crankshaft broke completely off the motor just behind the flywheel......absent the 5" spinner, 18/10 prop, and the flywheel, the plane shot straight up, and only blind luck and an excellent pilot saved it with a wheels up landing....I had purchased the 41 new from Bennett, who refused to have anything to do with repair or replacement.......My advice, get a Zenoah G-45 and enjoy years of dependable flying....
11-28-2009, 11:16 AM
#13
RE: US 41cc Engine problem
The G62 and the G45 wave basically the same exterior dimensions
I always saw a G38 used on the same planes as the Q42 and US41. The US/Q 41/42 used a 18 X 10 at around 7200. Everyone used a smaller prop on the G38 and it turned more rpm. The G38 weighs less than the Quadra. A G45 is probably heavier?
I always saw a G38 used on the same planes as the Q42 and US41. The US/Q 41/42 used a 18 X 10 at around 7200. Everyone used a smaller prop on the G38 and it turned more rpm. The G38 weighs less than the Quadra. A G45 is probably heavier?
