piston wash

[chrisdoc0608]

im replacing my head right now and i took a look at the piston wash. How long does it take for piston wash to show a difference, the pistons were showing a lean condition when i bought the motor (all the piston top was dark on each cylinder) the edges are now showing some sines of the dark areas clearing up around the perimeter. i have put about 2-3 hours on the motor while tuning. how long would it take to show a good piston wash from the lean wash if it were dialed in correctly

ps the dark circles are the focus feature on my camera

 

[#ZERO]

I'd clean the carbon off those piston tops with some carb cleaner and try it again.

You should see signs of piston wash after using 3/4 of a tank of fuel.

 

[chrisdoc0608]

ill do that as soon as i get back sunday, thanks #0

 

[Shonuff]

Why does a lean condition darken the top? I would think just the opposite.

Thanks.

 

[D-Roc]

the extra unburnt fuel from rich conditions washes the pistons clean.

 

[Shonuff]

It was that picture that prompted my question.

Thanks Roc.

 

[Watcon]

Piston wash.

I think you are too rich on the bottom, and way too lean on the top.. The carbon will wash off soon enough without manually removing it. Possibly take a look at the tuning tips posted on here somewher, but I would reccommend going up in jet size (not just turning out the screw) and start over.
You dont say what your compression ratio is, but if you are near the edge of pump gas tolerance, the pre-ignition will also cause the piston tops to overheat and form carbon easier.

Randy

 

[ANT]

Why does a lean condition darken the top? I would think just the opposite.

Thanks.

more of the mixture is being combusted and burning it on the top of the piston. i dunno if thats the correct wording for it but basically it. too rich not all of the mixture is combusted so more gas is left on the top of the piston.

something like that i think.

chrisdoc i think it's running lean.

 

[chrisdoc0608]

thanks guys, but i ended up getting it pretty close. My problem getting the jets right was a coil that was going bad and giving intermitten spark, when it finally went out my pistons had so much unburnt fuel that the tops are now clean. I ended up going up one more jet size on the high. I will be getting a tach this summer to properly tune it but its damn close now.

 

[DAG]

is it just me or does that front piston look like its been melted away??!!! mine did this when it was running lean.

looks like i can even see the ring.. only a matter of when that ring is going to fold over and grenade your engine

 

[chrisdoc0608]

is it just me or does that front piston look like its been melted away??!!! mine did this when it was running lean.

looks like i can even see the ring.. only a matter of when that ring is going to fold over and grenade your engine

I dont know about all of that, the front piston looks just like the rear piston as far as the gap and how much of the ring is showing. Compression is even on both cylinders and there are now wear marks or melted areas on the pistons or cylinder walls. It has ran just fine since i put the motor in.