Bogging when not on reserve setting

[400ccHomemade]

Ok, technically, this is a motorcycle question, but I have a question about my homebuilt trike. It has a motorcycle engine etc. I was just wondering if anyone had any ideas for me. The way it is desinged, you drive around with the gas tank petcock in the "on" position. When you start running out of gas, you switch the petcock to "reserve". I think the way it works is, gas doesn't just pour out of the tank, I think there is a diaphragm that opens when a cylinder pulses. Now, what is happening is, when I am in the reserve position, the trike runs perfect. But when I try to run it in the on position, it bogs out and eventually fuols a plug. Now, the first obvious answer is I am low on gas. I'm not. Besides, if that was the case, I would be running out, NOT bogging out and fouling plugs. I am pretty sure that the "reserve" and "on" positions both run gas through the same diphragm. Any ideas here? Weird one.

[bigredhead]

empty the tank and remove then clean the petcock....

on the ON position the stem is higher in the tank.. when you switch to REZ it lowers the mesh to grab the remaining gas in the tank... i think it's simply dirty.. and in the rez position it gets enough gas to run.. but in the ON it's choking.

[ATC crazy]

I also agree...take apart or replace your petcock because there is dirt or rust in it.

I would also suggest purchasing a fuel filter and install it between the tank and the petcock so no dirt gets into your petcock, carb, or your engine

If Im not mistaken, most fuel lines are 1/4". You can find fuel filters that fit at any auto-parts store