HOws this piston look?

[Delarado]

Pictures coming up.

Looks like its been run a bit lean (I knew that) But nothing too serious.

Just seeing what other people think as I have no idea really!

Any input appreciated

Cheers

[Delarado]

HOws this piston look?

[Delarado]

HOws this piston look?

[n00by]

looks fine to me.

[Stuart]

I generally look for any scores in the piston liner and piston if all smooth but compression low then I replace the piston ring and bang it all together again. If any scores on the liner or piston then I replace them all..

[smcb1]

looks fine to me too. give to a good rub with some alcohol wipes and all should be good to go again

[tonystevens]

Looks ok to me too, at the bare minimum id be tempted to fit a new ring while youve got the engine out.

[davec_7]

Looks OK to me. It might be worth replacing the bearings while you have it apart, you can also look at the piston ring itself when you take it out, but from what I can see its fine. I assume it runs ok and there is plenty of compression and it sounds alright?. I always check the temperature by putting a finger on the rear of the crank case and if I can leave it there without me haviing to take it off because its too hot to touch then the engine is not running too learn.

Hope this helps
cheers

Dave

[mark_w]

Looks fine to me, why do you think it was run lean?

[Delarado]

Because it was marked, i saw on a video once that the piston should be clean or it has been run lean.

I only took it out to have a look at it, its back in there now! (Although I have put a shim in there)

When your tuning these you tune so it sounds right rather than for maximum power dont you? (I.e it'll make more power lean that it will when its just right?)

Just wondering when to stop. I think I had it roughly about right before, now I want to muck it all up again and tune it myself for practice sake

[Made2Fade]

Nothing wrong with that piston!

[waveydavey]

Its about the sound, the power and the amount of smoke Carl. I probably use the amount of smoke and the sound. As you know I was having problems with my YS last weekend, plenty of mid range power and quick recovery but the top end was struggling. I knew it wasn't going to go pop but I also knew by the sound that it wasn't right. Removing the Align 3 way filter allowed the fuel through and although I had messed up the needles I knew that it was going to tune. So have fitted a MOAS and will start again on Saturday, I very rarely feel the backplate as I can tell by the sound and the smoke whether it's one way or the other. Once it's roughly there it's then that it comes to fine tuning it with a click here or there on the top or the mid, remember that they both affect each other

[mole hunter]

Year, piston looks fine but what's going on with the insulation on those wires?

[electricsceadu]

without looking at the whole piston you cann't tell if ifs ok or not correctly
but by the pictures shown it is servicable

[trillian]

Regarding the tuning, where you want to be is that point just slightly on the rich side of the hypothetical 'perfect' point. The thing about tuning for max power is that where the absolute max power is would be too lean, you'd have power for a few seconds but then as the engine heats up it will start to lose power and when the piston expands too much it begins to score the liner.

On some engines the margin is narrower depending on how close the piston fits to begin with. Most newer engines have a pretty wide margin for error.

Not long ago I found a nice article on tuning, I'll try to find it again. Basically the approach was starting with the idle mix and doing a pinch test to determine if it's set correctly (this probably won't work on a pumped engine though). Then starting with the high and mid needles at the factory settings, going next to the high needle and lastly the mid.

I'll see if I can dig it up I think it was on RR which is back up again now.

A while back I did this with two of mine, starting from scratch because of the colder weather and doubts about a few things and I discovered my idle was too lean on one engine and the high needle was too lean on the other. I'm happy to keep them a bit on the rich side even if I'm giving up a bit of power. I guess in theory you could get the tuning closer using a carbsmart as it can make those fine adjustments as the temps change but I have never tried one myself.