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What’s the nozzle for and why is there a jet in the crankshaft bearing?

Started by Marqus, November 20, 2022, 02:04:11 PM

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Marqus

Hi,

Can anyone explain what the nozzle is for, that sits behind the generator and sometimes gets scratches from primary chain?
And why is there a bronze jet in the lower crankcase half???

????????????

Thanks

Pat Conlon

There is an oil jet that directs oil onto the starter chain, is that what you're referring to?
https://fjowners.com/index.php?topic=19016.0

#23
1) Free Owners Manual download: https://tinyurl.com/fmsz7hk9
2) Don't store your FJ with E10 fuel https://tinyurl.com/3cjrfct5
3) Replace your old stock rubber brake lines.
4) Important items for the '84-87 FJ's:
Safety wire: https://tinyurl.com/99zp8ufh
Fuel line: https://tinyurl.com/bdff9bf3

RPM - Robert

Quote from: Marqus on November 20, 2022, 02:04:11 PM
Can anyone explain what the nozzle is for, that sits behind the generator and sometimes gets scratches from primary chain?

Pat already covered the nozzle jet for the starter chain.

Quote from: Marqus on November 20, 2022, 02:04:11 PM
And why is there a bronze jet in the lower crankcase half???

The oil "jet" is a restrictor Yamaha installed into the center main bearing journal. The reason I believe is that main bearing journal doesn't have any other function other than to lubricate the bearing, so it doesn't need as much oil as the other journals. Journals 2 & 4 provide the oil to the connecting rods. The right bearing sends oil to the cylinder head and the left bearing needs the additional oil to provide a more stable bearing surface to keep the crankshaft centered to control the ignition rotor movement.