Honda GXH50 throttle linkage with pics

Discussion in '4-Stroke Engines' started by HoughMade, Jan 12, 2008.

  1. HoughMade

    HoughMade Guest

    OK- I was able to get some pictures of what I did. I will try to explain what is shown in each picture.

    Background- I removed the entire external governor assembly- that is, everything outside of the engine case from the arm that attaches to the shaft that comes out of the case up. When i started this, there was nothing- nothing attached to the black plastic arm that actuates the throttle butterfly. The pictures will show this. Here we go.

    I will do this over three posts, just to be clear. These first pictures show the PTO side of the engine and will deal with the throttle return springs.

    They show the same thing from different angles. I had to experiment with about a dozen springs before I got a pair that pull the throttle shut reliably, but was not too hard to actuate.

    You will note two small, matching aluminum brackets at either end of the springs. These are window or door screen brackets that hold a screen it and are available at most any hardware store. I drilled small holes.

    As you can see, the springs are anchored under a valvle cover bolt- hey it's there, why add stuff. It is rigid and positions properly.

    The other end, where the springs are attached to the throttle is hard to see, but better in later pics. Essentially, the steel wire linkage that attaches to an arm to pull the throttle open is bents in sort of "Z" shape. It is this wire that goes through the end of the aluminum bracket and then into an existing hole on the throttle arm. I hope that this along with the pictures explains.

    Next chapter- the throttle cable attachment.

    Attached Files:

  2. HoughMade

    HoughMade Guest

    Now we are on the cover side of the engine. Here you can see where the throttle cable comes from the handle. There is plate that is attached by two of the valve cover botls that extends beyond the spark plug boot. This is still not far enough to interfere with your leg- or rather, my leg. This securely hold the cable sheathe. I found ascrew on cable end in my junk box. I think it is a generic lawn mower throttle cable piece. The clip is from my local Ace hardware and as i said, holds the sheathe securely.

    The cable ataches to an arm that is located, again, from a valve cover bolt. If you have kept track, you know I am using all four valve cover bolts. While the other three used the stock bolts, I made a stud for this one so I could take the arm off and adjust tension on it easily. This is important because the arm needs to be able to rotate freely. I used a stainless 4mm bolt (I think) of appropriate lenth and cut the head off. I then threaded it into the hole and placed a nut on it to secure the valve cover (all this and i never took the valve cover off, but don't woryy, it is really not hard to do even with all this, I know valve adjustment will be necessary). This leaves enough of the stud exposed so that I could put a flat washer, a sping washer (wave washer, and another flat abd a lock nut on it so that it moved freely, but does not rattle around.

    The arm that is attached there is "T" shaped, this will show in a later picture better. Currently, as you can see, it is made from a stright piece bolted to an angle, but I may fabricate one piece. The barrel I used to attache the cable is available from Ace as well (mine at least) and "throttle parts"- go figure.

    As you can see, when the cable is pulled, the "T" piece is pulled back and because the steel wire (generic lawm mower solid throttle cable) is attached to the arm of a "T", instead of the arm itself, it pulls to the side and back instead of just back- to get smooth throttle response, it has to pull out (towards the side of the bike, and back (really towards the front of the bike).

    Next post- more detail on the "T" piece and linage to the throttle plate.

    Attached Files:

    Last edited by a moderator: Jan 12, 2008
  3. HoughMade

    HoughMade Guest

    Part three:

    The picture here is taken fron the carb side of the engine and the point is to show steel wire from the "T" piece and the aluminum screen door/trhottle return bracket attach to the black plastic throttle arm.

    I think you can see here what I mean by the "Z" shape on the wire. The wire is attached by one of the barrel and screw throttle attachments to the "T" arm, then the wire extends over the aluminum bracket and is bent down at a 90 degree angle. It is then bent at another 90 degree beneathe where it passes through the throttle arm. I do not mean to imply that it is bent in place- it is bent before assembly. The nice thing with using those barrel and screw connectors is that you can adjust the cable and steel wire to get just the right tension.

    Attached Files:

  4. srdavo

    srdavo Active Member

    very nice design.

    hooking up a throttle cable to some of my contraptions, is always my least favorite part of a build.

    Thanks for taking some of the guess work out of it!

    Do you have any concerns about the eventual wear at the pivot point on your "T" arm?
  5. HoughMade

    HoughMade Guest

    That was a thought, but as it rotates about 30 degrees and there is not constant motion- not much. Also, the wave washer takes up some slack, so even with some wear, it will not get sloppy.

    Plus, you have to understand that I am a sunny weather recreational rider- I will likely go years and years without that being an issue- people who ride much more would still probably go a long time. I guess i could mount the T arm with a replaceable bronve bushing- faster wear, but somewhat "self lubricating" and serviceable. Thanks for making me think about it.
  6. srdavo

    srdavo Active Member

    No.....THANK YOU, for taking some of the thinking out of my next builds!!! :D

    Nice work.