1984 Aero 50 top speed help

[captaincodfish07]

Hello. I inherited a 84 Aero 50 from a friend and am working on it. I can get it up to ~32 with half throttle but when I open it up all the way it starts to slow down and lurch. Does this mean I have potential to go faster if I can get more or less gas to the chamber? I have adjusted the mixture screw and found little speed variation. A friend suggested I try a different needle. Any advice on how to optimize the speed? I have cleaned the carb inside and out. Thanks!

[maddog]

Take off the front pulley, if there is a ring held on with 3 screws take it off and you should 40mph.

[Wheelman-111]

Greetings:

Lurching beyond half-throttle suggests the main jet is wrong. Pull and examine the spark plug. Post pics if you can. Darker then Oak is rich. Maddog believes there is a restrictor on the variator. That may be, but lurching suggests power, not transmission is the main issue.

[vintagegarage]

I have a dead stock 1984 Aero, and I can get it to 40 MPH only while going down a pretty good hill... I might get to 45 mph on a very steep hill. 35 on the level is about normal for mine. In any event, to answer part of your question, it isn't normal for the engine to slow down and lurch once you open the throttle past 1/2. It should gradually increase in speed past 32 as you increase the throttle and the engine should run smoothly. Once you are at full speed, you may be able to maintain full speed on level ground with slightly less than full throttle, but the engine should definitely not slow down if you then give it full throttle. Also, the mixture adjustment should have little or no influence on full throttle running, but should make a dramatic difference to the quality of the idling and ease of starting the engine. Set the mixture screw adjustment by following the instructions in the online shop manual. Verify that you have full flow of fuel to the carb by sucking on the vacuum tube to the fuel valve, and watching the flow of fuel out of the fuel line to the carb. It should run out in a pretty good stream, definitely not a dribble. If you have just a dribble, you may have some sort of blockage between the tank and the fuel valve.

[captaincodfish07]

Thanks for the responses. I do need to adjust the mixture screw because it takes a long time to start up and doesn't idle well. I was thinking that was because of a faulty bystarter but haven't been able to test it yet. And I will post pictures next time I work on it. It definitely feels like it wants to go at least 35-37.