700 Throttle setup help please.

[Rctintin]

First off, I am using a YS, and because the carb is 'spaced' off the crank case, the push rod provided is too long. Luckily, I have a M2.5 die, so extended the thread and cut the rod a little shorter (length set to servo bolt center to throttle barrel centre).

Now, I am using a DS650 tail servo on the throttle, and using the '6 legged' futaba horn, (outer hole at 13.5mm). The YS arm is 14.5mm, and the futaba '4 legged' horn is 16.5mm. I first off tried the '6 leg' horn, and needed to use 120% on the high end point (causing binding) with the throttle set to 50/50 on curve, and carb at 50%, and then full back trim to cut engine.

That is too much 'end point' for the govner, so do I go with the '4 legged' horn, and reduce the throws, or a large circular disk, and drill my own hole at 90deg to push rod, and at 14.5mm as the YS arm is? (It's not a YS arm, but a Bling QuickUK alloy one)

Thanks for any help, cheers,

[ddracer]

What servos are you using on your Cyclic? If it 610's then I would drill a disc with the same spacing as your throttle. ( if your throttle servo is slower than cyclic then you can use a longer arm but getting true linear is harder) Set the EPA to 80 each way. Your rod is already the same lengh as the centers to start.

Set the curve linear, trim closed. Pull the throttle arm all the way closed the open it by 2mm. Set the lengh of the rod. Open the throttle and and check rod lengh. If its to short increase the EPA by 5% each way and repeat the process.

If you get to a point where its just a fraction out you can use the EPA to tweek but try to keep the EPA at each end within 5% of each other.

You will find that the throttle will always lead the pitch, The engine will start at about 1/4 trim the the curve will be as close to true linear as possible. If you can get hold of Rays Authrotive Dvd it has a section on this and it has always worked for me and the other guys at the field.

[Rctintin]

Thanks for the info DD. Whats EPA? And having watched finless bob's vid on the 700 build, he said about keeping the end points as close to 100 as pos, or it will upset the gov settings.

Cyclics are 610's

[heligray]

hi epa is end points adjustments hope this help, best off luck

[ddracer]

Fair point if your running the govenor. But the same rules apply start with 100% EPA but after setting try to have a max difference of 5%.

[Rctintin]

OK, will give it a shot. Cheers.

[Rctintin]

OK guys, really struggling here!

I have drilled a disc at 14.5mm the same as throttle arm. I have no sub trim, I have 90 deg between pushrod and arms. Now, I pulled full back trim, so when moved up, the engine is at idle, and full back trim, throttle closed.

However, in order to get the right length, I have had to go to 79 on the low EP, and to get full throttle, I have 127! ? WTF?

Also the YS manual said 40% throttle at hover, but using 50/50 on a linear curve, hover is at approx 65% so my engine will be at 65%! Some serious head speed there I think! I know I can use curves to lower that, but what am I missing here?

Please bear with me, it's my first nitro for 13 years!

Thanks for any help here.

[Rctintin]

Thinking out loud here, and I have brain fuzz, and need to sleep, BUT, If I am at 127 and 79, I cant be at centre where I drilled my hole. I've gone +27 and -21 from 100 EP. that makes 48, half it, =24, 24- 127 =103 and 24+ 79 =103.

So should I set my end points to 103 high and low, and then 50/50, and thats my centre throttle?

(Or am I talking utter bo$$ox)

[ddracer]

Yes if you need the extra travel then that is fine. As both end points are the same your govenor will be fine with it.
This is one of those things that take some getting used to (Like setting up a gyro). Once you get the nack of it, it is easy. At low stick low trim did you have the throttle arm on the carb open 2mm? The reason you do this is because 99.9% of carbs are closed (Hole is totally shut) for a bit of throttle movement before it stats to open if that make sence? Where as the arm stops moving the the hole is fully open.

[Rctintin]

I had the trim fully back and then with the link off the throttle arm ball, adjusted the end point till it popped on without any binding with a fully closed carb. There seems to be a fair bit of movement from fully back trim to mid position.

Do I do as I said before, by going back to 103 each end, and then getting centre that way?

Cheers guys

[heliward0]

place the throttle linkage in the centre of the servo (so you can see the servo horn screw through the link rod) and the same down to the carb barrell screw and lenthen or shorten untill both the screws can be seen in both the eyelets.. this SHOULD give you as near as damn it a correct linkage lenth.. then its just fine adjusments to 100% perfection, (hope this makes sense)

[heliward0]

also remember that your no looking to get it perfect on the closed position because the idle is not fully closed its above the closed line,, you will only fully close it by trim clicking it right off,,(like -15% for instance)

[Rctintin]

Thanks guys. You will see by my first post that the rod length is spot on centre to centre. I now have 14.5mm on both disc and throttle arm. So every thing should be equal as it is with the aileron links and arms. Will have another go tonight, but have probably spent 3 hrs on this little bit!