I need a fast "save your bacon" answer here, and I need it in 2 hours or less...

 

'82 BRAT... EA 81 with Weber carb.

 

When it's cold, it stumbles/misfires like hell from 1750-2750 RPM, then gets better at about 3k, and flawless at 4k RPM.

 

Once warmed up, there is no stumble at all if the throttle is applied gently... but if I ask for power, it still stumbles/misfires from 2250-2750 (but not quite as bad as before), then not as bad from 3k-4k, then flawless...

 

It was running great before I put it in the garage for the winter. I've tried carb cleaner and new fuel with no effect. Quick ideas as to what's wrong?

Lotsa possibilities.

 

I would start by examining the ignition system.

Moisture under the disty cap or on the coil,fouled plugs,bad wires etc.

 

Fuel-wise,-make sure the accellerator pump works,could be lean from fuel delivery problems too(low float level,plugged filter etc.)

One simple thing - since it's related to temp - check that the choke is closed when it's cold and that there is power to it, it's openeing as the engine runs, fully open when at running temp, etc.

 

Pull out the secondary idle jet and inspect the hole in the tip of it - you may not have a secondary idle jet but often the Weber's do. It is used to assist in progression from primary to secondary - which could be part of your problem at mid-throttle. It's a quick check.

 

After that all the ignition components should be checked for sure. Cap, rotor, plugs and wires. Clean and regap the plugs and see how it runs if you can't replace them all right now.

 

GD

Thanks guys... just got it fixed in time.

 

The plugs were borked. Replaced 'em and it runs perfect!

i love how rock solid and simple weber's are, easy to pass the problem onto somthing else.

It's not cold enough this winter in our area, but the weber will ice over badly when it is really cold. Glad you got it fixed quickly.