I am working on a Big Stick 60 ,arf. When I fitted up a OS FS90, I saw the throttle lever is on the left. I dropped a 60 2 stroke there and saw a rh throttle. The plane is setup for rh operation. How would I run a lh throttle on this plane? I wonder if I have to use a flex cable to accomplish this. I sure want to use a 4 stroke. Thanks for any info.

crabby62,

If it were me, I'd remove the setup that is there now and redrill a new hole in the firewall on the side you want it to be on and run a new Ni-Rod. Ten minute job if that.

Just like this, one servo arm, one 1/4" piece of fuel tubing for a bushing, one 440x1 inch bolt and two 440 nylock nuts. Easy Peazy

You're going to have a blast with that model. I've got one and it flys great.

You could just leave the original grey tube in there and if you every wanted to switch engines the throttle tube would be there for you to use.

I am looking forward to flying this plane, It will be my first plane over ,60 size. After I sort out this engine problem, I will be ready to roll. ( as soon as the snow departs. )

I had a similar issue with a plane (SPAD Debonair) I built. With the engine horizontal and a fuel tank in place, I had to bring the throttle wire out on the top right (looking at the firewall from the prop side), but the control lever was on the bottom left. I don't like flex cables.

What I found was that careful bending of music wire allowed me to create a suitable hard linkage. I trial bent up soft wire until I had the right configuration.

The important part was that I found in my first attempt or two, that using 90° bends would not work. It allowed too much flex. Once I kept the bends more in line with the way the thrust was being transmitted, I was able to configure a hard wire with only two bends, each about 135° each. It’s strong and very light, yet flexible in the event of a crash.

jack

Flex cables are great as long as they have a straight run. <G>

Before the thin flex cables were available, I would periodically see someone's bent/crooked high friction installations of the old thick flex cable at the field or a club meeting. Sometimes it was all I could do to work the throttle (sometimes surfaces) with the friction being so high. Then they wondered why their batteries discharged earlier than they thought they should and why their servos were so slow.

It used to be that pushrods/actuation mechanisms were a macho thing with most modelers. Criticize someone's linkage and you were looking for a fight. This was when servos were very inaccurate, weak and super expensive, which forced many folks to drive multiple control surfaces and extraneous doohickeys with a single servo. Ah, the good old days. Many of these installations were disasters just looking for an empty smoking hole to fill.

It is wonderful to have inexpensive radios/servos/receivers available that work at least as well as the old equipment and most of the time, far better than the old equipment.

It isn't uncommon to see my models, both kit built and ARFs, with two or three guide shafts installed in the fuselage and visible on the firewall. I just build them in automatically these days because I know that eventually I will change out the engine from one type to another (two/four-stroke). I also install the Edson Universal Adjustable Engine Mount on these models for the same reason. These mounts last and last and last, plus new jaws and other parts are available from the manufacturer (RJL/MECOA) for a mere pittance. Believe me, these mounts will outlast a dozen models with ease. Contrary to popular belief, they are NOT heavy at all.

Throttle linkages require a bit of engineering creativity. They are something that I enjoy designing and installing. Always have. Good luck with yours.


Ed Cregger


*Corrected spelling

I am not real comfortable doing most of the suggestions. Basically, making a jack shaft across the width is too complicated and bending wire sounds too flimsy. Sounds like the only alternative would be a Sullivan Gold-N-Rod, or a flexible cable pushrod. Still seems like a lot of friction. Life sure is full of hard choices!!
Thom

I don't know that OS Specifically.... but many if not all Saito 4 strokes (and lots of other engines) allow for you to simply rotate the carb 180 degrees....

My method above is virtualyl friction free. The throttle requires nearly zero effort to move.

Hobbys, I guess I'm none too smart. I didn't seem to understand your pics. Do you have a jack shaft that goes under the engine from right to left?
Thom

Which are exactly the same reasons why I like a bent piece music wire. Strong, light and simple.

What Hobbsy proposed is good. The end of the (white) lever is pivoted, the wire from the servo is connected at one point and the lead to the carb is connected at another point. It's basically just a way to change the direction of the force being applied to the throttle.

Jack

Nice and simple!

This FS-90 carb doesn't reverse. No money for anything more. Retirement is a time to use what I have. Maybe I should put the old K&B .61 and make more noise.

Hmmm...just found some pics....it looks like it might....but I don't have the engine here..

Crab, just turn the servo around in its mounting hole if mounted sideways, if mounted longitudinally on the wrong side I just make a new servo mount where I want it. I use the "swing lever" so I don't have to run the servo rod right out of the firewall to the throttle arm, that's to binding and cramped.

Here is a similar set up on an RCM with a Saito .62. Me, "Big Dave" on the left, "Little Dave" in the center and Grandson Jerin on the right.

I really like that idea to remount the throttle servo. I can put the servo on the left and run a rod straight to the carb. Thanks Hobbsy. To me, thats thinking out of the box.

As supplied, the FS-70S2, FS-91S2 and FS-91S2-P have their
throttle lever on the right hand side and needle-valve control on
the left. However, where more convenient for certain installations,
these positions may be reversed after rotating the carburettor
through 180° horizontally.
Proceed as follows.
RELOCATION OF CARBURETTOR CONTROLS
Remove the intake pipe mounting screws from the cylinder head
(taking care not to lose the flange gasket [91S2/91S2-P] ) and
the carburettor mounting screws from the crankcase cover plate
bracket.
Detach short tube connecting carburettor to pump unit (FS-91S
2-P) and gently rotate the carburettor through 180° without
separating it from the intake pipe or removing the enclosed Oring
seal.
Re-install the complete sub-assembly of intake pipe and
carburettor, making sure that adjoining surfaces are clean.
Tighten screws evenly and firmly but not excessively.
Remove pump mounting screws from the crankcase cover
plate lugs, carefully rotate the pump clockwise one-quarter turn
and attach it to the second pair of lugs provided, taking care that
the central tube connecting the crank chamber to the pump
diaphragm chamber is not twisted.
Finally, make sure that all external tube connections are secure
and do not leak. As per OS web site. Hope this helps.

That's a nice setup, but all you really have to do is run the pushrod out of the stock nyrod location out past the cylinder and then bend a 180 in the pushrod and go back to the throttle arm.

The first time I heard of that I laughed, but then I tried it. I eliminated the bellcrank and it worked perfectly every time. Boy, was I red faced. Fortunately, I was alone at the time.


Ed Cregger

I'd check this suggestion first.

Greetings; My OS FS 90 is not able to feverse the carb. Sorry.
A note to Ed Cregger , today I'm going to try your setup. After all, this is a fun hobby, good education for all. Thanks

Greetings; My OS FS 90 is not able to reverse the carb. Sorry.
A note to Ed Cregger , today I'm going to try your setup. After all, this is a fun hobby, good education for all. Thanks

Crab, here is a little hint, when you bend the rod 180 degrees make the end you're connecting to the carb end up slightly below the hole in the throttle arm when the throttle arm is straight up and down. That way the rod won't have to flex so much as the arm travels through its arc and the hole position is lower at the end of the travel arc.