Oil jets

[Rob62]

I was chatting to a guy at the Mallory festival of 1000 bikes a couple of weeks ago. I was telling him about my CB750 project. He asked me if I knew that the oil jets needed to be drilled out to a larger size than standard to ensure they dont block up. I said I hadn’t read about it but I did know that they can become blocked.... he seemed quite confident that it was a common well known modification. What do you guys reckon?

[Trigger]

Never enlarge a oil jet, this will reduce the pressure in the bottom end 
It is not called a restrictor jet for no reason.

[Rob62]

Yes, it'll certainly reduce the velocity. You ever come across any enlarged jets trigger?

[Trigger]

Yes, it'll certainly reduce the velocity. You ever come across any enlarged jets trigger?

Yes, on fecked cranks 
Drilled out jet on the left, original on the right, and the crank was the result   

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[MrDavo]

Yes but the jet wasn’t blocked, was it?

[Nurse Julie]

Two options, well 3 actually. Blocked jets, the cam is toast. Drilled out jets, the crank is toast, along with oil pump, gearbox bearings, shells and when the swarf gets up to the jets, your cam is toast as well. Standard jets with no blockages and not drilled out, nice running engine with no damage.
If anyone requires any drilled out jets, knackered oil pumps, gearbox bearings etc, or knackered cams, we have quite a collection!!! 😭😭😭😭

[paul G]

Two options, well 3 actually. Blocked jets, the cam is toast. Drilled out jets, the crank is toast, along with oil pump, gearbox bearings, shells and when the swarf gets up to the jets, your cam is toast as well. Standard jets with no blockages and not drilled out, nice running engine with no damage.
If anyone requires any drilled out jets, knackered oil pumps, gearbox bearings etc, or knackered cams, we have quite a collection!!! 😭😭😭😭

 

[Rob62]

Well put Julie..

[UK Pete]

Can't believe people tell such bullshit tales
The engines are designed to run with these jets as all posts mention it's gonna kill the engine drilling them out


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[UK Pete]

It's much like the old tale of putting sawdust in the engine to quite it down
WTF  I have heard several takes of that 🤣🤣🤣

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[Moorey]

You can picture the thought process.
I know if I drill these out it will let more oil through.
End of thought process.
It also tells you a lot about those who told you to do it.

[adespin]

Is there any way of telling if the jets are blocked or on the way to getting blocked without removing the engine ? do the jets provide a splash feed to all parts under the cam cover ? is it possible to see the jets in action through the tappet covers while running ? Many questions i know, but i'm getting paranoid, i adjusted the tappets about three hundred miles ago, and i can now hear them again, i will check them again to see if they have altered.

[adespin]

Just done a forum search and i now realise that i have asked a similar question last year, dementia must be setting in 

[Nurse Julie]

Did you get an answer last time....dont forget the rest of us must have dementia setting in too 🙄🙄🙄

[adespin]

Did you get an answer last time....dont forget the rest of us must have dementia setting in too 🙄🙄🙄

Sort of, still not sure if the cam carrier bearings are pressure lubed or splash fed.

Thanks,
Adrian.