so I finally finished building my phantom 85 a few days ago, balanced cranks new bearings all that stuff. so yesterday I retarded the timing to get it to stop popping so much and it worked for the most part there is just a bit less power. so I had an exhaust gasket leak and when I took off the exhaust I looked into the cylinder and there looked to be a ton of carbon buildup on the piston. so then I pulled the plug shows signs of running rich and hot and there is way too much carbon buildup on the piston for an engine that's only been running for an hour (i run the same fuel mix on my other engine and that cylinder is practically spotless). additional info: running with a g2 reed and pz20 carb (haven't touched the needle position or jetting yet) and a bh8s sparkplug.
need help identifying running rich, lean, hot or cold.
- Thread starter sabir
- Start date
Hi... I have so many things to say here... so let's just get started.
1st.. That plug looks grey... (that mean's a little lean); & 'popping' is usually a lean condition... Most carbs have smaller jets than what's needed for these engines, & reed valve engines always need even bigger jets to run correctly.... Install bigger jets.
2nd... That #8 spark plug is way too cold!!! (use a NGK #6) the piston top looks black with un-burned oil... not soot.
Using the correct heat range plug is very important to completely burning the gas/oil mix!!
Always remember that using a colder plug doesn't make a colder running engine; it makes a cr@ppy running engine!
3rd... what gas / oil mix are you using??? (I suggest using 32:1 or 40:1)... I'm guessing you're using too much oil).
4th... How did you retard the timing????? That's something I don't recommend messing with unless you have serious engine tuning experience! (PUT IT BACK TO WHERE IT WAS)... The factory timing works best!
There's probably a lot more you can do, but this should get you heading in the right direction.
Report back here & let us know how it went after you make these changes.
1st.. That plug looks grey... (that mean's a little lean); & 'popping' is usually a lean condition... Most carbs have smaller jets than what's needed for these engines, & reed valve engines always need even bigger jets to run correctly.... Install bigger jets.
2nd... That #8 spark plug is way too cold!!! (use a NGK #6) the piston top looks black with un-burned oil... not soot.
Using the correct heat range plug is very important to completely burning the gas/oil mix!!
Always remember that using a colder plug doesn't make a colder running engine; it makes a cr@ppy running engine!
3rd... what gas / oil mix are you using??? (I suggest using 32:1 or 40:1)... I'm guessing you're using too much oil).
4th... How did you retard the timing????? That's something I don't recommend messing with unless you have serious engine tuning experience! (PUT IT BACK TO WHERE IT WAS)... The factory timing works best!
There's probably a lot more you can do, but this should get you heading in the right direction.
Report back here & let us know how it went after you make these changes.
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Just saying... don't you think the engine is running a bit rich? If it was running lean there would be little to no carbon buildup. I say it's way to rich and/or the plug is to cold, like Venice said. Furthermore, Unless I am mistaken, if you retarded the timing too much, couldn't the engine potentially misfire? Since the gasoline molecules would be lese dense (or essentially farther away from each other in a given space) I think it would be safe to assume that the spark plug is having a harder time igniting the mixture because there is a higher chance that the spark will not ignite a gasoline molecule, therefore unable to start the chain reaction of combustion with all the other gas molecules in the cylinder (hence, that's why the spark plug looks oily and wet).
I suspect that there is a lot of mixture going unburned even though the engine seems to be running rich. I will assume for now here is so much tartar because unburned oil may stick to he piston, cylinder, cylinder head, spark plug, etc.; and just linger around until it eventually "dries up" when combustion actually takes place.
Just my take on the matter, so don't beat me up if I am wrong. Safe travels, that is, if you ever get this problem sorted out; lol.
I suspect that there is a lot of mixture going unburned even though the engine seems to be running rich. I will assume for now here is so much tartar because unburned oil may stick to he piston, cylinder, cylinder head, spark plug, etc.; and just linger around until it eventually "dries up" when combustion actually takes place.
Just my take on the matter, so don't beat me up if I am wrong
. Safe travels, that is, if you ever get this problem sorted out; lol.