Piston wash???

[slyrydr]

what you are looking at is essentially two different conditions....the time you spend the most throttle time on is the wash around the edge of the piston, but it's quite likely that you have a lean spot which is what the overall lighter color is in the center of the piston....so what was the last minute or so of the engine operating conditions before you shut it off? if it was wide open, you have a lean spot there, or maybe it was in the 6500 rpm area, in which case you are probably lean there...getting reliable wash readings in the field with a laydown engine is very difficult and time consuming without a borescope...learning to read spark plugs is much easier to deal with....and what octane fuel are you running?....from a good name brand station, or something else?....head mods to your engine?....all play a part in deciding what it is you're looking at.....back to spark plug readings....if you look at the ground electrode (the upside down "L"), you have the vertical part and the horizontal part that goes over the central core electrode....if the coating (the burned on deposits) are on the horizontal part of the electrode, with the tip burned clean you have a rich condition....as you lean up the mixture, the line between burned deposit and clean electrode will migrate around the corner of the "L" electrode until it is on the vertical part of it....when the deposit line has migrated about 1/2 the way between the corner of the "L" and the very top of the threads of the plug, you're right where you want to be....you need to check various rpms' for about a 1 minute run to check for mixture throughout the rpm range of your engine....the wash on the top of a piston generally reflects the most time at any one condition that the piston sees...only by riding at a specific condition, and immediately checking wash will piston wash be reliable....but plug readings are much faster, and when correlated with egt readings, will make for a dependable tuning aid

 

[Warrior67]

what you are looking at is essentially two different conditions....the time you spend the most throttle time on is the wash around the edge of the piston, but it's quite likely that you have a lean spot which is what the overall lighter color is in the center of the piston....so what was the last minute or so of the engine operating conditions before you shut it off? if it was wide open, you have a lean spot there, or maybe it was in the 6500 rpm area, in which case you are probably lean there...getting reliable wash readings in the field with a laydown engine is very difficult and time consuming without a borescope...learning to read spark plugs is much easier to deal with....and what octane fuel are you running?....from a good name brand station, or something else?....head mods to your engine?....all play a part in deciding what it is you're looking at.....back to spark plug readings....if you look at the ground electrode (the upside down "L"), you have the vertical part and the horizontal part that goes over the central core electrode....if the coating (the burned on deposits) are on the horizontal part of the electrode, with the tip burned clean you have a rich condition....as you lean up the mixture, the line between burned deposit and clean electrode will migrate around the corner of the "L" electrode until it is on the vertical part of it....when the deposit line has migrated about 1/2 the way between the corner of the "L" and the very top of the threads of the plug, you're right where you want to be....you need to check various rpms' for about a 1 minute run to check for mixture throughout the rpm range of your engine....the wash on the top of a piston generally reflects the most time at any one condition that the piston sees...only by riding at a specific condition, and immediately checking wash will piston wash be reliable....but plug readings are much faster, and when correlated with egt readings, will make for a dependable tuning aid

Thank you very helpful..)

 

[frock]

If you have pyrometers and can watch them at WOT. If it is jetted right, it should run around 1100-1150 degrees F. at 1200 and beyond that is to lean, if it is 1100 and colder, it is rich. Just saves the headache of trying to look at the piston.

If you've dialed in a motor this way and not burned down it was pure luck. The EGT numbers mean nothing till you establish where the motor is dialed in at using plugs and piston wash, you must do this to properly dial in a motor. My brother in laws 925 genesis ran over 1400 deg all day for over 4 years before he rebuilt it (preventive maintenance). He installed his EGT probes to far from the piston and this caused the high temps, but he established his baseline first then used his EGT temps to keep his motor there afterwards with no problems.

 

[racer75]

what you are looking at is essentially two different conditions....the time you spend the most throttle time on is the wash around the edge of the piston, but it's quite likely that you have a lean spot which is what the overall lighter color is in the center of the piston....so what was the last minute or so of the engine operating conditions before you shut it off? if it was wide open, you have a lean spot there, or maybe it was in the 6500 rpm area, in which case you are probably lean there...getting reliable wash readings in the field with a laydown engine is very difficult and time consuming without a borescope...learning to read spark plugs is much easier to deal with....and what octane fuel are you running?....from a good name brand station, or something else?....head mods to your engine?....all play a part in deciding what it is you're looking at.....back to spark plug readings....if you look at the ground electrode (the upside down "L"), you have the vertical part and the horizontal part that goes over the central core electrode....if the coating (the burned on deposits) are on the horizontal part of the electrode, with the tip burned clean you have a rich condition....as you lean up the mixture, the line between burned deposit and clean electrode will migrate around the corner of the "L" electrode until it is on the vertical part of it....when the deposit line has migrated about 1/2 the way between the corner of the "L" and the very top of the threads of the plug, you're right where you want to be....you need to check various rpms' for about a 1 minute run to check for mixture throughout the rpm range of your engine....the wash on the top of a piston generally reflects the most time at any one condition that the piston sees...only by riding at a specific condition, and immediately checking wash will piston wash be reliable....but plug readings are much faster, and when correlated with egt readings, will make for a dependable tuning aid

thanks im trying to look at my pluges and see what you mean but kinda lost if you had a cupple pics or know where some are it would help me verry much

 

[785RMK]

If you've dialed in a motor this way and not burned down it was pure luck. The EGT numbers mean nothing till you establish where the motor is dialed in at using plugs and piston wash, you must do this to properly dial in a motor. My brother in laws 925 genesis ran over 1400 deg all day for over 4 years before he rebuilt it (preventive maintenance). He installed his EGT probes to far from the piston and this caused the high temps, but he established his baseline first then used his EGT temps to keep his motor there afterwards with no problems.

Must of been some hellish pistons to go over 1400 deg. since aluminum melts at 1220 deg. But anyway, using your plugs to check is a good way, I just can't see pulling you head to check piston wash unless I was racing it. For the guy to go riding a semi stock sled, most will perform really well if your close with your jetting and clutching.

 

[racer75]

help

any one know where some pics of some plugs are or have any that i could look at to relly under stand what i'm reading

 

[tundramonkey]

Here ya go.

http://tsrsoftware.com/read-plugs.htm

 

[mmurray70]

Here ya go.

http://tsrsoftware.com/read-plugs.htm

Anybody here using that "mixture ring" from that site to read plugs? I've been using it for years and it seems foolproof. More commonly used by motocross riders.