81 ET250 running rich

[06apexak]

I swapped the Keihin carb to a mikuni round slide, vm30. Starts great, idles good, but no power (bogs down) mid range to top end. Runs like you have the choke on. Choke free play seems ok, but I did notice in the parts list that the needle is a 3.3. I see a lot of folks here sayng it needs to be a 1.5. I have a new pump, new carb, new fuel lines, new fuel filter, and new uni filter. I am a bit stumped.

Any ideas?

 

[jfpsteve]

Et250 carb

Hi, I believe a 3.3 needle will not stop the flow of a fuel pump and will flood the engine. You need to install a 1.5. 3.3 is for a gravity flow systems like a motorcycle with tank mounted higher than carb and with very little or no pressure. A 1.5 is used in a pressurized system which is what happens when a fuel pump is used. (low mounted tank on a snowmobile). Good luck!!