jetting carbs

[mudbug3]

I had my friend weild up come custom two into two exhaust pipes with 1 5/16" inch RLV mufflers on the end of each pipe. I also made a long intake runner using truck radiator hoses and attached a cone shaped , K&N air filter on the end. After my friend had all of the different pipe sections weilded all together , I then took my Argo for a 30 minute test ride through the woods by my friends house to see how my new exhaust pipes sounded. My pipes now have a much deeper idle and a really nice rumble when ever you twist the throttle. When I got back to my friends weilding shop I then checked to see how much blueing I had on each exhuast pipe. Each pipe was a medium blue all the way to where each RLV muffler was attacted. Not good. It was late in the evening so I did'nt have the time to pull out the plugs and see how each spark plug electrode looked, but it seems to me that my engine is really running lean now. My friend has about 20 really small drill bits. My plan is to drill out the low speed jet and the main jet one size bigger and then recheck both spark plugs after running the engine at different rpms. I plan to drill out the low speed jet and main jet one size bigger until I see the electrode colour change to a tan or light black colour. I've heard that it's better to jet an engine a little richer because this helps it run cooler? I hardly ever run more than 2 mph in the places that I choose to go. At what engine rpms does the main jet kick in?

[Joe H]

Hey mudbug, I think we are going to need some more info. What engine, what carb, how long are the pipes from the port to the muffler and are they equal length, are the pipes chrome? Sounds to me as if you never get off the low speed jet with the kind of driving you do and for that a little more back pressure from the exhaust is good, not really the type of driving the requires a flowed out exhaust unless your 2 mph is at full throttle!

[Model Citizen]