Can't see carb throat...

[Skiddz]

Bought a Raptor 50V2 off flea-bay just about two years ago. Built, partially set up but has never seen fuel. With the long weekend, I decided once and for all to get it flying so took it apart, reassembled and got the head/tail/gyro set up and now I'm working on engine stuff.

Engine is an OS .50SX-H and I can't see the carburetor while it's installed in the heli so I have no idea when the carb is completely closed. I can BARELY see the edge of the carb's throat above the head when I look in from the front of the heli, but can't see if it's open or closed.

How the heck do I set up the throttle if I can see what the carb is doing?

[Funky]

First, connect the throttle servo link to the throttle arm on the motor. Make sure the ball on the servo is the same distance from center as the ball on the throttle arm. The servo arm and throttle arm should run parallel to each other.

Turn down your high and low throttle servo endpoints to 50. Go to low stick, drop your throttle trim to 0 and adjust the low endpoint until the arm closing your throttle stops moving. Next go to high stick and adjust the high endpoint until the servo stops moving. Make sure its not binding in either direction.

This works great for my 9303 with a mechanical throttle trim. You can do the same thing with a digital trim, but its not as quick. Some radios use a digital trim with a throttle cut. If your radio has a throttle cut button you will need to program the button to move the throttle stick to fully closed. Adjust the digital throttle trim to find a good idle point.

[creightoncarr]

I do the same thing, except I like to position the ball links on the servo and throttle arms so that I get full travel on the throttle arm with 100% high and low ATV's.

[Funky]

I like to use the lower ATVs so my throttle moves a little faster than my collective servo. This should allow my throttle servo to slightly lead my collective servo while punching the throttle. Its only a fraction of a second's difference though so I am not sure how much of a difference it really makes. The way it was explained to me is like a car going up a hill. If you start to give it gas just before the hill the car gets up the hill much easier than gassing the car at the same time you start climbing a hill.

Although even without a difference in ATVs, the load on the collective servo probably slows it down enough compared to no load on a throttle servo to have the same effect :dontknow

[Kinger]

I think you guys are missing the point. I don't think he's asking how to set up a throttle servo to engine linkage, he's asking how does he know what direction to rotate the carb barrel to get to full throttle vs. having it fully closed.

If I'm not mistaken, full throttle will be when the carb barrel is rotated counter clockwise and fully closed when you rotate it clockwise. Another way to tell if the carb is full open or closed is to turn your engine over with your starter. (Make sure your glow igniter is not hooked up and you don't have fuel going into the engine.) Then as you are turning the engine over, rotate the carb barrel back and forth. When it sounds muffled, the carb is closed.

[Skiddz]

I'm pretty sure I know which way is closed (not my 1st nitro model - just my 1st Raptor) on the engine. I just wanted to be able to see the barrel itself as I tweak the throttle trim. I'm on a 9C so not sure if I'm going to use a switch for throttle cutoff or use one of the pitch sliders. Guess I'll see what "feels" best when I get to that point.

Like Funky, I'm going to set the throttle to open slightly faster than pitch increases.

[flyn-n-va]

On the OS engine there is marks where the throttle arm shaft goes into the carb. Line up the 2 marks on top and the carb is fully closed. Push the arm and line it up with the mark 45 degrees around and its fully open. It also has some marks in between for mid stick but they are not needed. I have a 9c also and set the throttle up just off the fully closed mark, then go to the throttle cut screen and activate that to close it the rest of the way with a switch. I use the trainer switch, that way it will only work if the throttle lever is all the way down. It keeps you from killing the engine accidentlly.

[Skiddz]

Noticed those tonight when I got the throttle linkage all done. Got it set so that at 100 ATV, the servo is JUST binding at full deflection both ways. I'll dial down the end points to stop that and then work on setting idle speed with trim and cut with switch H (Trainer switch)

Just gotta get the wiring cleaned up, mount the Rx, flight pack and governor and see if she'll start...

[flyn-n-va]

Cool! If you are using a GV-1 Gov. try to keep the ATV close to 100%, I think it has to be atleast 50% to work.

[Skiddz]

Throttle Jockey, but I don't have any docs for it.. Will have to check the TJ website to see if I can fine some docs.. If not, I'll probably pick up a GV-1...

[Funky]

Throttle Jockey, but I don't have any docs for it.. Will have to check the TJ website to see if I can fine some docs.. If not, I'll probably pick up a GV-1...

Take a look at the Multigov from Aerospire if you are in the market for a new Gov. It works great with tons of fine tuning options.

Here is the manual for the TJ Pro

http://www.modelavionics.com/docs/pro_instructions.pdf

And Throttle Jockey

http://www.modelavionics.com/docs/instructions.pdf

[Skiddz]

Cool, thx Funky!

I actually did find the docs for the TJ, but will bookmark that page for future reference should I lose 'em again...

Now if I could find the box with all the bling and 2 sets of SAB blades in it, I'll be set. (Went missing about a year ago when I had new wood floors put in the house. I'll probably find it when I move.. heheh)

[BarracudaHockey]

Yep, you want equal end points. Before I install then engine I run a fine tip sharpie in those grooves, makes them easier to see when you set it up, most of the time fuel spray will make the marks disappear eventually but it will get you through initial setup. In the old days I used to scribe a low mark, high mark and an index mark on the throttle barrel.