1980/1 25 hp Mercury with the shift in the tiller handle
SN 6185615
I picked this up a few weeks back knowing it needed some work. Started digging into and found the tube assembly (aluminum shaft running the length of the handle that attaches to a pulley and the cables on the motor end and to the twist grip on the other) in the handle to be catching. While taking that apart it broke the aluminum just in front of the plastic pulley. The catching was because it had mostly broke/ripped already. I started investigating why that would possibly break. I couldn't find any reason why it should have broken there (burrs, bends, etc.). On the off chance it was caused in the handle, I started working that end. It was smooth considering it's age. That wasn't the problem. Went the other way then. I was doing the process of elimination when I finally got to the Throttle Cam. The throttle arm (to the butterfly valve) will get hung up part way through it's travel.
First thoughts were a burr or nick in the throttle cam, nope. Moved onto the butterfly valve arm. It moved very well. Checked the plastic bushing on the end of it to make sure it was turning, it turns smooth. No binding or sticking. Well, then it has to be something in the throttle cam pivot, it moves fine but... Took that off, it's straight and appears true but I did notice it rides in a slotted bushing that was set up so it would give it adjustment front to back (original PN 23-86968 supersede to 17764A 2 from what I can gather). I can't seem to find a "sweet spot" for it, it will get hung up at some point between idle and 3/4 of the way to WOT depending upon where it is set at.
So, my questions are these:
Is the bushing designed to be set and left alone or is it suppose to slide to allow full travel?
This bushing has a shoulder/lip on it that rides along an edge on the block side. This appears to be designed this way or is that shoulder/lip just "worn in" because of the age of the motor? I can't find a decent picture of the bushing to know one way or the other. If just worn in, then I should be able to adjust the slot in the bushing to whatever angle works best for the throttle cam after said shoulder is removed, right?
Finally, there is 2 different carb configurations for this motor, I have to verify which I have, but what is the difference in throttle cams between the 8799A 1 and 96096 PNs? Could that be my issue, wrong throttle cam on it? I'm curious if they have the same slope, same pivot point, etc..
I've been a long time lurker but couldn't find anything on this topic. If I missed it, post a link to it for me. Thanks!
SN 6185615
I picked this up a few weeks back knowing it needed some work. Started digging into and found the tube assembly (aluminum shaft running the length of the handle that attaches to a pulley and the cables on the motor end and to the twist grip on the other) in the handle to be catching. While taking that apart it broke the aluminum just in front of the plastic pulley. The catching was because it had mostly broke/ripped already. I started investigating why that would possibly break. I couldn't find any reason why it should have broken there (burrs, bends, etc.). On the off chance it was caused in the handle, I started working that end. It was smooth considering it's age. That wasn't the problem. Went the other way then. I was doing the process of elimination when I finally got to the Throttle Cam. The throttle arm (to the butterfly valve) will get hung up part way through it's travel.
First thoughts were a burr or nick in the throttle cam, nope. Moved onto the butterfly valve arm. It moved very well. Checked the plastic bushing on the end of it to make sure it was turning, it turns smooth. No binding or sticking. Well, then it has to be something in the throttle cam pivot, it moves fine but... Took that off, it's straight and appears true but I did notice it rides in a slotted bushing that was set up so it would give it adjustment front to back (original PN 23-86968 supersede to 17764A 2 from what I can gather). I can't seem to find a "sweet spot" for it, it will get hung up at some point between idle and 3/4 of the way to WOT depending upon where it is set at.
So, my questions are these:
Is the bushing designed to be set and left alone or is it suppose to slide to allow full travel?
This bushing has a shoulder/lip on it that rides along an edge on the block side. This appears to be designed this way or is that shoulder/lip just "worn in" because of the age of the motor? I can't find a decent picture of the bushing to know one way or the other. If just worn in, then I should be able to adjust the slot in the bushing to whatever angle works best for the throttle cam after said shoulder is removed, right?
Finally, there is 2 different carb configurations for this motor, I have to verify which I have, but what is the difference in throttle cams between the 8799A 1 and 96096 PNs? Could that be my issue, wrong throttle cam on it? I'm curious if they have the same slope, same pivot point, etc..
I've been a long time lurker but couldn't find anything on this topic. If I missed it, post a link to it for me. Thanks!
