I have Stock carbed 85 gs. pretty much full emmisions. rats nest. etc.. have to hold foot on the gas pedal to keep it alive from a cold start. once it warms up it will hold a rough idle. it will drive pretty good. but it jerks from time to time. just recently it will hesitate in the lower rpms. then gain power at about 3500 rpms. now it wont idle and wont start even when warmed up. i have to spray starting fluid every time to get it to start up. will run and drive. just will die if i let my foot off the gas pedal.

 

Sounds like fuel delivery issues, which, beyond this tidbit, I will leave to the Experts here to suggest.
Have you changed the Fuel Filter??? should be done _yearly_. Easy and cheap. ($4 at any auto store). $10 bottle of Seafoam in the gas tank will do you NO harm either.
Presume you have reasonably new plugs and dizzy cap/rotor?

Stu Aull
80GS
Alaska

 

You have junk in the carb and it needs to be pulled off cleaned and rebuilt. Search on jeff20B
posts about rebuilding nikkis. You also need to make sure your tank is clean and not supplying
junk in the gas and the filter is fresh as well.

Short term a bottle of seafoam in the tank, fresh filter and spraying the bejeesuz out of the
carb with a good aerosol carb cleaner product may get you past this temporarily. If you take the
top off the carb make sure you don't touch or loose any parts for the floats or adjust anything
at this point.