No throttle stop

[jebbab]

Hey all. I just picked up a used DA 50 the motor was just returned from DA, or so I was told. It does look like it has all new gaskets. My question is that the throttle stop screw has been removed? No big deal or should I order one from DA??? I would think I could just use my servo travel to set idle?? What do you all think. This is my first DA motor and just want to make sure that everything is right. All of my other gassers have stop screws. Thanks

[flyin woodbutcher]

no you dont need the screw. You need to be able to close the throttle all the way with the servo. DA 50s are great engines.

FWB

[Temptation]

The first thing I did to my DA 150 was remove the throttle stop screw. As FB said, "you need to be able to control the entire travel of the throttle blade with the throttle servo.

DA uses Walbro carbs. In many applications a throttle stop screw is needed. In our application it is not needed.

Mike Darr

[DATech]

We remove the stops before shipping. Better to have the servo dictate the end points.

[JoeAirPort]

Really? Then how do we know where the throttle end of travel really is? The reason I ask is because couldn't it start going back the other way and cause some weird throttle response? Just trying to understand this.

[main_gears_bent]

I don't believe its possible to make the butterfly in the carb turn completely around, Your linkage would bind up somewhere in the rotation, and they just aren't capable, try it by hand, it will stop.

[DATech]

Hello
At full throttle, the plate should be vertical in the carb bore. A degree or 2 either way will have no negative effect. The plate is mechanicly limited from opening much past vertical by a stop. Your throttle servo should be trimmed to hit it's end point just at or slightly before hitting the stop.

The carb plate is normally just slightly opened at idle. Low throttle trim is used to completly close the plate and kill the engine. A throttle stop screw would need to be completly backed out to allow this. (Or removed...) The plate will stop against the carb wall and not alow it to over rotate. With the servo end points set correctly and a very slight amount of flex/play in the linkage, there will be very little, if any, bind when the throttle plate is closed.

If the user is not careful and the standard throttle arm with it's stop is removed to use a different arm setup, the plate can go past center and basically be reversed. This is when you will have some very strange throttle response due to the strange airflow on the fuel orfices from the plate being in the reverse position. (We see this once in a while on engines sent in for service...)

[jebbab]

Thanks Guys, I just wanted to make sure that I wasnt missing something here.