Throttle linkage?????
 

I just set an OS70 FS in a Kyosho p-40 and it is mounted inverted..now...the thottle arm on the engine is setting right in front of the hole in the firewall where the fuel tank tubing comes out..i have to figure a way to hook a throttle linkage that comes out of the firewall off to the right so that the linkage going back to the servo is not interfering with the fuel tank.
If i bring the throttle rod up and off to the right of the arm on the engine how can i get it to move the carburator on the engine..
Any suggestions are welcome.I can't use the Ubend method because the control rod would have to go straight back which would hit the fuel tank in behind and there is not enough room around the arm off the carburator to move forward and back as you can see in my pic.

RE: Throttle linkage?????
 

Realativly easy, just run the throttle push rod out to side and well past the throttle arm. Bend a hairpin ( U-turn) turn in the throttle pushrod back to the throttle arm.

RE: Throttle linkage?????
 

I have the same problem. I am using an L bend that is sprung so that it engages the arm and won't come out. There is nothing retaining it. Seems dicey, but it works.

RE: Throttle linkage?????
 

Consider reversing the carburetor, maybe there's better clearance on the other side of the engine.

RE: Throttle linkage?????
 

When I have tried the U bend, I have had more felx that I felt comfortable with. I use a bell crank. Usually I can mount some plywood to the engine mount and then install the bell crank on that. The ones made for CL have a bearing and work well, and are inexpensive. Serves the same puropose as the U bend, but with more positve control.

JR

RE: Throttle linkage?????
 

It's kind of ridiculous how O.S. set these up. I can't figure out how they expect us to hook up a linkage. If using an EZ connector, then you have to have access to the set screw and that may not be possible if the cowl is built into the fuselage. If using a Z-bend, then there's no way to hook it up. If using a clevis or ball link then there's not room for it to move without hitting the firewall.

RE: Throttle linkage?????
 

Get a metric allen wrench that fits the throttle arm. Move it 180 degrees as in the pic. You should then be able to use a z-bend.

RE: Throttle linkage?????
 

OK, but how are you going to connect and disconnect a z-bend if the engine is cowled in such as this? It will work if you use an EZ connector at the servo end so you can pull the whole pushrod (maybe), but not if you use a real connector. EZ connectors are bad news and I don't use them anywhere. In the case of this aircraft, the rear of the engine has to be pulled out first, so the wire has to be severely bent before the engine is out far enough to disconnect the Z-bend.

RE: Throttle linkage?????
 

Du-Bro makes (or made) a gadget to help with 4 stroke throttles. It's a sort of idler arm that mounts to the engine mount (sort of like one arm of a u control belcrank) The pushrod runs from the servo to the arm, then another rod from the arm to the throttle. It serves the same function as a u-bend but is much more slop-free and professional looking.

RE: Throttle linkage?????
 

CafeenMan

I personally agree. I don't like e-z connectors. I would use a bellcrank. However, many, many people will use the e-z connector because it is.. easy. I am not really very fond of z-bends, especailly in a situation like this where it creates a metal to metal link. On the other hand, I have been very unhappy with the results of using a u-bend.

RE: Throttle linkage?????
 

Here is a pic showing the Dubro 4-stroke throttle linkage being used on a Kyosho Corsair with an OS 91FS pumper:

http://www.whitetyphoon.com/rc/kyosho_corsair/pic04.jpg

I have used these linkages in the past, and they worked pretty well.

RE: Throttle linkage?????
 

Here was a nightmare engine install. A .52 four stroke in a Sig Rascal 40. This first pic shows the throttle pushrod in the 180 degree style recommended in the manual. It was very spongy and flexible. Second pic shows a Z-bend, and was better but made it hell to pull the motor. Finally went to a stranded cable and EZ connector. The cable ran through a nyrod tube and was firm enough to not flex but would allow the engine to come out easy with the cable still connected to the engine.

Jesse

RE: Throttle linkage?????
 

Neat Richard, Clean, neat setup. Thanks for the heads up. Now, what is the Dubro part number?

RE: Throttle linkage?????
 

Dubro part number is 665.

RE: Throttle linkage?????
 

Altho the DuBro thingie is very professional, I have had success doing the same thing with an old servo arm. Thread a #4 sheet metal screw into the motor mount with the servo arm on it. attach the throttle pushrod to one arm, and attach the servo pushrod to the opposite side. Reverse the channel if you have to.

RE: Throttle linkage?????
 

I use a flex cable with a ball link on the throttle arm. If the tank is in the way, I use the bell crank mounted to the engine mount with the link arm method.

RE: Throttle linkage?????
 

I have the same issue and used the dubro arm before but cannot this time as the throttle arm is directly behind the motor and not out to the side like my ohter four stroke. I love 4 strokes but the throttle arm hookup is a rea PITA.. (pain the the ....). I;ve had the ball links vibrate or come off and do not want to fly around at full throttle till the few runs out anymore :)

RE: Throttle linkage?????
 

Here's my Magnum52 4-stroke mounted in a SIG 4*-40

RE: Throttle linkage?????
 

I have used this method in similar situations where the carb arm is metal. It might be OK on a plastic arm but I have not tried it..

Take a 1 inch bolt that fits the hole in the throttle arm. Take a ball end pushrod and fit the ball up against the head with a nut. Use two nuts and fit the bolt to the throttle arm. Use Locktite.

If needs be the plastic part that screws onto the rod can be shortened to as little as 1/4 inch and still have a good grip.

This gives you a 7/8ths inch offset from the throttle which is enough to get a direct link from the servo to the thottle.