Need to get it straight

[Root_Doc]

OK, I am relatively new at this. To begin, I am in Louisiana, {low elevation}. 70 degrees. T6 and the T6 boxless air filter. I am running 1:40 klotz. Riding around like a grandma and fouled the plugs with carbon. The main is a 280 and the needle is the toomey needle. Not sure what size this is. If anyone knows please help. Ran a plug chop and got almost no color change. Yes, I know seems lean. I will try a 300. The main question I have is that if the mixture if based on a fuel to air ratio, then would it not be true that if the oil mixture was increased, would this not decrease the amount of actual fuel to the carb making it more lean. In other words would I need to change the jetting to an even larger main if I wanted to go to 32:1.

I have read many forums but I havent found any that discussed this issue. thanks. If this is a dumb question just tell me because once again I am new at this.

Root

[dajogejr]

NEVER change your oil to fuel ratio to compensate for jetting changes.

32:1 or 40:1 is fine, but figure which you want to run and stick with it.

 

With no air box, those temps and elevation, you should be at or around a 340 main.

You probably fouled it out because the low speed jetting...or pilot, air screw and/or needle aren't adjusted properly...

 

To answer your question, the less premix you put in the gas, the richer the jetting becomes, but not by very much.

Less oil in the gas allows it to pass through jets more quickly, therefore richening up the mixture.

[MILO]

someone correct me if i'm wrong, but i think you are talking about 2 different things here. premix vs. fuel to air

 

mixing more or less oil in the premix basically only changes your mix ratio. granted, too lean of a mix ( not enough oil) can cause problems due to lack of lubrication for the cylinder. even though it may seem to run awesome on a lean condition, it's not good and won't last for long. too much oil in the premix (rich) can foul your plugs, and also cause it to run like shit.

 

changing premix doesn't really require jetting changes.

 

jetting changes should only need done when either the amount of fuel flow, or air flow is changed, or temp or major elevation changes. increasing air flow would require increasing jet size to compensate, or you would be running lean.(too much air) also causing overheating and engine damage. increasing fuel level without additional air would be rich, and you may foul plugs, run like shit, and so on.

 

i don't think that premix and jetting affect each other much at all. though each is extremely important to tuning your bike properly in their own respect.