1990 stock 49 cc zuma stalls

[Beerfish13]

New to this forum. Thanks in advance for any advice.

My 1990 zuma has a manual choke. It starts very easily and has a good initial idle. Within a few minutes, idle drops to just above a stall and will stall if left alone on the stand. At this low idle, the headlight also dims even with a charged battery.

When riding, it runs great after you get past idle and on a flat road will do 32 to 35 mph. At a stop sign though, it again idles down and wants to stall if not coaxed along with the throttle.

I am assuming this is a carb issue and would appreciate advice on best way to adjust as the carb is buried behind the airfilter and under the seat/tank assembly. There does not seem to be a practical way to get in and adjust the carb screws. I am also not sure which screws I should be trying first.

[florida derbi rocket]

It sounds like the Idle screw. It is usually a knob not a screw.Even with my Delortto 19mm....I still have to take the rear rack ,seat and back shroud off my 02' to adjust it....pissed.

[Beerfish13]

Thanks Florida.

I am up in NY so it is still cold up here. Might take it apart next weekend and do my best to adjust it. It seems that the gas tank is in the way so I am not sure how it can be adjusted once the seat and tank are off.

Any advice on how to adjust a carb on a 90 zuma 49cc?

[Beerfish13]

Fixed the problem. For those interested...
had to take off seat, luggage rack and main side cover.

Tank, carb and air cleaner assembly left in place.

Found that the breather hose was missing and that the rubber skirt protecting the carb had been duck taped to almost completely cover the breather hole.

After putting on a new breather tube, the throttle screw was way out of adjustment which was easy enough to adjust. Scoot fires right up and now has a normal idle. Top speed with a 215 pounder is now about 38 on the stock speedo with a flat road and about 25 uphill.

I did notice that the pilot air screw was totally stripped. It is impossible to remove without removing the carb and drilling. I left that alone for now and will wait a month or so and see what my spark plug tells me.