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I seem to remember hearing somewhere that the different needle slots had something to do with tuning for differing atmospheric and mechanical conditions or something silly like that.

kp

SteveD wrote:What is the recommended distance b/w needle/seat replacement?

In mileage? It's not that simple. When you see your mileage drop, it's time. I've heard of people having worn needle jets after 25k miles, but that's pretty unusual. 40-50k is pretty normal, some make it longer. I think it makes a big difference what state of tune you keep your bike in, as the wear comes from vibration.

To the best of my knowledge my needle jets have 240,000 k on them.
I think it's time to change them.
Or put my needles into the second notch instead of the third.
On my recent trip of 2,200k my brothers 81 RS was beating me by at least 2 litres per tank full.
Yep, definitely time to change the needles and jets.
His RS also makes more power than mine.
But that's ok, mine has more dents.

Yeah, at 240k, pretty much everything but the crank and the wheel bearings (if correctly maintained) have probably gotten pretty sloppy.

I've already smoked the crank, and several sets of wheel bearings.
But I got a lovely crank from Nick in New Zealand, and believe I have finally sorted my preload issues.
The cranko destructo wasn't my fault, honest! It was my broken oil filter bypass spring that did it.
Everything else was my fault tho'.

I've taken the suggestion of GSPD and double checked my valves.

Here's what I found after closer inspection, left side intake rocker....

The rocker block is now installed in upside down, just keeping torque on the heads until new parts arrive....

That's gouging all along where the rocker contacts



Then there's the broken/missing bearing cages on one end



A few broken needles from the bearings and final picture, gouging on the shaft itself (right side)



I think this was the extra noise I heard, and maybe? led to poor performance by the vavle/rocker?

They are roller bearings, not 'move up and down' bearings.
This was caused by the rocker having too much vertical play at some time in its life.
The vertical play should be 0 + a film of oil.

Unless you can account for every part of the cage and all the rollers,
you should pull off the barrel and check the lifters for shrapnel.
or in the very least , pull out the pushrods and go fishing in there with a thin telescopic magnet.
You might find some missing parts.

gspd wrote:They are roller bearings, not 'move up and down' bearings.

"Move up and down" bearings?????

I was wondering where the parts of the cages would go. I don't know about the needles, but the "outer" cage and 1/2 the inner cage on one side aren't there.

I was wondering where they'd be.

Could I pull the jug partially, like doing the push rod tubes? To look for pieces, or would that not afford me enough of a view?

Adding a PS, this could have/probably happened hundreds of miles ago. Would the broken bits have made it down into the oil pan by now?

Is there anything that would keep them near the push rod hole or even on that side of the engine?

pkboxer wrote: Would the broken bits have made it down into the oil pan by now?

Is there anything that would keep them near the push rod hole or even on that side of the engine?

The chunks can't get past the lifters and into the oil pan unless they are completely pulverized.