why?

[warrior111]

Ok, i took the top end out of my quad about a week ago, anyways, when it was running it was running rich, the plug was super black. But, i got a pipe, filter, high comp pistion, bored, ect.. with my airbox lid ON. could this be why it was running rich? Was it not getting enough air?
I would like to figure this out for when i get it running agian, any help would be appreciated.

 

[20warrior00]

take the lid off and see if that helps, if not just jet it a bit leaner

 

[warrior111]

but i dont understand, if it got mods, why would it be running rich on stock jetting?

 

[20warrior00]

my warrior runs rich to with all my mods (pretty much the same as you have) and i still have stock jetting

 

[yamarider]

Mods don't necessarily mean it's going to need richer jetting. Usually it does, but one thing that can affect this is more vacuum, which pulls more fuel through the same size jet. There are tons of factors in this, and every build is a little different. If all else checks out fine, maybe you just need to jet down leaner than stock and see how that works for you.

Have you checked the float height on the carb? A float set too high can also cause it to run richer with the same size jets.

And yes, the stock airbox lids are very restrictive, especially for a modded engine. I wouldn't think it would be enough to make it run excessively rich on a modded engine, but it could be a contribuiting factor.

 

[warrior111]

thanks YamaRider and 20warrior00, the floats shouldnt be set to high, i got them set so the gas stops flowing when the floats are level, if they are set high gas poors out my over flow. And i will try taking my lid off, and if that dont help ill jet lower, thanks.

 

[jasonp]

but i dont understand, if it got mods, why would it be running rich on stock jetting?

I see you have a jet kit but say you are running the stock jetting?

Basically higher compression piston will take up more space up inside the combustion chamber. There is less area there for air now. So less fuel is required for a correct air to fuel mixture.

Sometimes a bad valve stem seal or a piston rings not seated or bore that wasn't done right causing oil to get into the combustion chamber causes the black (rich) look on the plug.

Also anything restricting air flow on the intake like dirty air filter or stock air box setup will make the engine seem to run richer. The stock setup on the warrior is pretty restrictive.