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Connecting rod Bushing

Old 06-08-2009, 08:19 PM
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acam37
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Default Connecting rod Bushing

Q: How many flights does it take to destroy the connecting rod bushing and crank pin when running improper oil content?

A: only 6

This is the result of running my ST G2300 on 32:1 oil ratio against the advise of people who know better. I figured it would fail, but not this soon. I had planned to send it to Ken Lambert for the needle bearing conversion, but had to fly it in the meantime. Big mistake.

I'm posting these pics just to show you exactly what happens to the bushing when you run it with low oil content, so there is no question about what will happen. Here is the proof.
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Old 06-08-2009, 08:42 PM
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richg99
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Default RE: Connecting rod Bushing

Just trying to learn here....if 32-1 is incorrect....what ratio is correct?  thanks Rich
Old 06-08-2009, 09:37 PM
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acam37
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Default RE: Connecting rod Bushing

The experts in this area recommend a 10:1 gas oil ratio which I believe is about 20% oil. I tried this ratio, but could not get my engine to run. It kept fouling my little 1/4 X 32 plug. Lowered the oil and the engine came alive, then quickly died. I hope Ken can save this engine for me. I think the rod bushing and pin are the only damage.
Old 06-08-2009, 11:26 PM
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adrian222
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Default RE: Connecting rod Bushing

I run my ryobi's at 50 to 1 and never had a problem and that is with basic two stroke oil infact the engine will blow smoke if I let it idle for a while.

Adrian.
Old 06-09-2009, 12:08 AM
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acam37
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Default RE: Connecting rod Bushing

Do the Ryobi's have needle bearings on the rod? I know they were purposely designed to run 40:1 or 50:1. Not a glow engine. They were designed to run 18 to 20% castor or castor-synth blend. Convert it to gas and lower the oil content without some modifications and that spells trouble. I found out the hard way.
Old 06-09-2009, 02:42 AM
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Jezmo
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Default RE: Connecting rod Bushing

I run my SuperTigre 51 and 90 at 16:1 using Redline Two Stroke Racing synthetic and on the 51 I have gotten over 35 hours on a single RimFire 1/4X32 plug.  The 51 has over 75 hours and still runs strong, the 90 has about 10 hours and runs great as well.  Both were converted using CH synchrospark ignitions, the 51 still uses the glow carb albeit somewhat modified and the 90 has a walbro on it.
Old 06-09-2009, 10:20 AM
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acam37
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Default RE: Connecting rod Bushing

Maybe after I get this final mod done I can have peace of mind knowing that it won't seize up and quit due to the wrong gas/oil ratio. I was thinking about using that gas that is already premixed. It comes in 50:1 and 40:1 in 1 quart containers.

I was at the saw shop the other day talking to the repair man and he told me that all these additives they are putting in the gas is reaping havoc on these small engines, especially the carbs. He suggested that I use the premix stuff and run the fuel lines dry before putting the plane up for the day.
Old 06-09-2009, 07:00 PM
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Twin Star
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Default RE: Connecting rod Bushing

If you live near a lake with a marina that sells fuel the boat fuel is exempt from the alcohol additive.
Old 06-11-2009, 08:00 PM
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tkg
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Default RE: Connecting rod Bushing

UH,,,10:1 is 10%......20:1 is 5%


ORIGINAL: acam37

The experts in this area recommend a 10:1 gas oil ratio which I believe is about 20% oil. I tried this ratio, but could not get my engine to run. It kept fouling my little 1/4 X 32 plug. Lowered the oil and the engine came alive, then quickly died. I hope Ken can save this engine for me. I think the rod bushing and pin are the only damage.
Old 06-11-2009, 09:55 PM
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mangolo
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Default RE: Connecting rod Bushing

10 parts of gas and 1 part of oil makes it 9.09% of the total volume of the mix; 9 parts of gas and 1 part oil makes it 10%



Waldo
Old 06-12-2009, 01:00 PM
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KenLambert
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Default RE: Connecting rod Bushing

it looks like the crank got kinda hot , blue, but it should be fine.

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