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Fuji 50 gas help

Old 12-30-2019, 12:21 PM
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TLCorsair
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Default Fuji 50 gas help

I need help identifying this issue. The underside of my P51 is splatted with black dots from the engine exhaust. Am I too rich/lean or do I have too much oil in the gas?
I have a Fuji 50 with a 22-10 APC prop. I mix 20:1 gas to oil. Also top end RPM varies with the season. All help appreciated.
Old 12-30-2019, 02:03 PM
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Truckracer
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Originally Posted by TLCorsair View Post
I need help identifying this issue. The underside of my P51 is splatted with black dots from the engine exhaust. Am I too rich/lean or do I have too much oil in the gas?
I have a Fuji 50 with a 22-10 APC prop. I mix 20:1 gas to oil. Also top end RPM varies with the season. All help appreciated.
You need to tune the engine for the season and use the recommended oil ratio. 20:1 is quite a bit of oil. But beyond that some engine / exhaust / airframe combinations just show more exhaust residue than others. Some oils largely combust in the engine and some pass through and don’t fully burn. If the engine is running right, I wouldn’t worry about it. Proper tuning will reduce the residue.
Old 12-31-2019, 01:25 PM
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TLCorsair
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Default Good advise

Thank you for the advise. I will reduce my oil ratio for the next gallon I prepare. Glad to know that seasonal adjustments are not uncommon. Happy New Year!
Old 12-31-2019, 08:56 PM
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DGrant
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20:1 is crazy rich on oil. I'd use Redline oil, mixed 40:1. That works in pretty much everything. I'd also look at your spark-plug at this point. If the engine is spewing oil(likely due to rich oil content), the plug is most likely nearly fouled. That plug will tell you a story too. If will probably be wet/oily/black... which means too much oil. There's a good chance anyway.

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