<div>Ok, so Irealize that this is an very silly question but Ifigured a quick post will save me some time in the shop.

Ipurchased aYS 91FZalready mounted on a Hangar 9 P-51 Mustang. This combo had been runup but never flown. Anyway, it came with everything but a transmitter so Iadded my own receiver and started to set the plane up. Unfortunately, with the way the engine is mounted Ican't see the carb intake very well and can't get a good read on if pushing the throttle arm forward opens or closes the throttle. Is it forward open, rearward closed? Iknow what my OSengines take but, after a lot of reading, YSengines seem very "unique" and Idon't want to take the engine off the plane to mess with the carb but Icertainly don't want to start this thing full throttle!

Thanks for the help!</div>

I guess it depends on the set up.  in my case the throttle opens when pushed back (or pulled back) toward the firewall with the throttle arm moving aft.  Unlike other four strokes, you look down from the top to see in to the carb throat in a YS.

I would set it up to run on the test stand and set the throttle in the mid position and start, then move the throttle on the tranny to see what happens.  Be careful as the enginne will be turning over pretty fast.  But that way you can determine the throttle control is reversed or correct.  That is if you push up the throttel on the tranny and the engine accelerates then it is correct.  If you push up the throttel on the tranny and the engines slows down to idle it is reversed. If reversed, then reverse the servo on your tranny and it is fixed.    Use end point adjustment, sub trim or the like to get the travels correct.

Good luck,

Chip

The throttle arm on a YS can be adjusted 360 degrees so based upon the configuration of where the arm is the throttle could be opening or closing. Here is what to look for......
Looking at the motor with the head up if the arm is set up pointing up(towards the head side of the motor and not the crank case)then moving back from the propeller to the firewallwould be opening the throttle.

Hope that helps. If you can't see the throttle arm then I would suggest pulling the cowl for abetter look.
Skids

<div>Thanks for the help folks!

JimmySkids, thanks for the detailed explanation. The motor is mounted inverted with the arm pointing towards the head. Since the firewall is so long it was hard to get a good angle to look at the carb intake without removing the engine, Ieven tried a little mirror! Using the little mirror Ithought Isaw it opening when Ipulled the arm back but Iwanted to confirm. Anyway, It looks like pushing the arm towards the prop closes the throttle and pulling it back opens it. This just seemed counterintuitive and Iwanted to for a second opinion!

Thanks, you all are great!</div>

Sounds like you've got it handled...... basically counter clockwise on the arm opens the carb. Clockwise closes. Another trick not mentioned was that WITHOUTGLOWattached you could open the throttle put a starter on the motor for 10-15 seconds, and the tank should build pressure....... if the throttle was closed it wouldn't build up the tank pressure.

Skids