Polini Cylinder Head Screws/Bolts

One of the great things about ultralights is that they are even more flexible than experimental aircraft in what a pilot can and can't do with them (within the few FAA/FAR Part 103 regulations). Engines are a major part of any aircraft and many options are available for ultralights. This Forum is for that discussion.

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ksatter26
Posts: 426
Joined: Mon Feb 28, 2022 9:06 am
Location: Farmersville TX

Polini Cylinder Head Screws/Bolts

Post by ksatter26 »

I was having a lot of trouble getting my 303 to start. I replaced the factory battery with one with a higher Cold Cranking Amps ratiing and that helped some.

I did note that I had a small amount of oily grey/black material along the cylinder. I thought this to be some Evans Cooling Fluid overflow from possible overfill. When cleaning this up, I found that at least one of the cylinder head nuts was only finger tight.

I torqued the nuts (13.2 ft-lbs), the screws (8.8 ft-lbs), and the spark plug (14.2 ft-lbs). This seems to really help in starting the engine.

Since I previously only ran the 303 for less than an hour total during startup and test runs, I'm assuming the screws and nuts were untorqued from the factory.
LA F2 Flyer
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Re: Polini Cylinder Head Screws/Bolts

Post by LA F2 Flyer »

Thanks for this Kurt. I'll certainly be checking mine as well! I've run mine for about a half hour so far. Time to grab a torque wrench!
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Badland-F5 Pilot
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Re: Polini Cylinder Head Screws/Bolts

Post by Badland-F5 Pilot »

LA F2 Flyer wrote: Thu Nov 21, 2024 9:50 am Thanks for this Kurt. I'll certainly be checking mine as well! I've run mine for about a half hour so far. Time to grab a torque wrench!
I guess this means, no plug and play with Polini! I also suppose now that I hear about this that I'll check whatever engine I get, just to prevent a repeat of the problem on my end. Thanks Kurt!

Todd
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mrpilotron
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Location: Omaha, NE

Re: Polini Cylinder Head Screws/Bolts

Post by mrpilotron »

Sounds fishy to me. This needs to be reported back to the factory so they are aware. A new engine should not require you to double check the factory assembly work.
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