carb adjustment

[jeff70]

Hey all, I have a few questions on carb adjustments.
I am running a K&N cone filter and have opened up the stock muffler. My main jet is opened to .042 and the pilot is stock. It runs good but doesnt seam to build enough RPMs. Also it smells rich if I adjust my screw out more than 1 turn.
What could be causing the Low RPMS, And why can't I adjust the screw out to the stock 1.5 turns??
The plug looks great, It does have a slight backfire till it warms up.

[1989Marathon]

Originally Posted by jeff70

Hey all, I have a few questions on carb adjustments.
I am running a K&N cone filter and have opened up the stock muffler. My main jet is opened to .042 and the pilot is stock. It runs good but doesnt seam to build enough RPMs. Also it smells rich if I adjust my screw out more than 1 turn.
What could be causing the Low RPMS, And why can't I adjust the screw out to the stock 1.5 turns??
The plug looks great, It does have a slight backfire till it warms up.

What motor and setup?

[jeff70]

stock G2 4" lift 22" tires
also I am running at 7500 feet

[Tinken]

That's about a 106 jet. If it smells rich and the plug is dark, it will bog on the top end as you suggest. As you lean the main jet back, your engine will rev as it would normally.
Ah, 7000 feet, gonna use less fuel higher in altitude.

[jeff70]

It does smell rich, but the plug looks perfect, a nice light tan. Maybe I will grab a few leaner jets before I head up camping again,

[sho305]

Must be altitude they are usually lean if you open up the airbox and/or exhaust.

[jeff70]

Yea, I was thinking along the same lines, I'm just looking for a cheap fix, this winter I will be putting a v-twin in it so I don't want to spend alot of money on the stock motor.

[sho305]

If the filter is on the carb you could try putting a little section of tube/hose on the carb then the filter. Sometimes it will flow more air from a tube (like a velocity stack) than it will right into the inside of the filter that is open, but that is just a guess it may not matter, so don't hold me to it lol.

You can also check your jet size with drills or a torch tip cleaner, then solder it shut and make the jet smaller.

[Tinken]

Originally Posted by jeff70

this winter I will be putting a v-twin in it so I don't want to spend a lot of money on the stock motor.

Same here, I was just trying to get as much out of the stock motor over the summer before big block this winter. As Sho recommends, you can solder the jet shut and use my drilling chart above to make the correct jet. The hole doesn't have to be perfect on these carburetors because it is only a fuel meter, where as the fuel then passes through the main nozzle and becomes atomized. Also the pilot circuit works with the main and is what you are adjusting with the screw. Because of your altitude, even the oem pilot may be too rich and that is why you are having to dial it back some.

Another thing that helped me was running an iridium plug, NGK BRP8EIX. They last a long time, are tough to foul and seem to burn through richer mixes.

[jeff70]

Thanks for the info guys, I am going on vacation this friday for 9 days. I should have plenty of time up camping to play with the cart.
Also I know part of my problem is the belt, but today my new Gates Gforce belt showed up, so with the new belt and leaning her out I should have a fun week.