MS 170 Throttle linkage question (choke won't stay engaged)

[garndawg]

OK, I'm obviously doing something wrong...

I have three MS 170's, all having their carbs rebuilt/replaced, and I'm obviously not putting them back together again correctly.

When the two nuts on the airbox are cinched down tight, the control lever won't stay in Choke. It springs back into the run position. I can loosen the airbox until it'll stay, but the nuts are barely finger-tight.

When the control rod is rotated to choke, it lifts the 90 deg section of the throttle linkage and binds it up against the little square bump on the bottom of the airbox. If I release pressure on the control rod, it springs back into the 'run' position (i.e. choke won't stay engaged). If I cut off the bump on the airbox (tried this on one saw), the linkage likes to pop out at the carb.

So I'm doing the following, but am pretty sure somethings wrong:
- Control rod under the linkage, with the 90 section resting on top of the throttle control bump
- airbox barely on there (nuts finger tight)

Also, do these saws use a gasket between the carb and the airbox or intake boot? Mine didn't have any, but I found a part that's listed for MS 170's, but it looks wrong for this saw.

Thanks for the help, gents.

 

[walterg]

No gasket on mine. Where did you put the spring steel.?
It goes on the top, not the bottom.

 

[walterg]

Here is a quick pic. The kill wire is not hooked up in this shot.

 

[garndawg]

Understood, I'm good on the kill switch and choke, it's the throttle linkage on the other end causing the trouble. Thx much

Sent from my SM-G900V using Tapatalk

 

[walterg]

Just to make sure you understand what im saying,
when you put the control lever back in, you should of lifted the flat spring steel up.
If you install it without lifting the spring steel, it will cause all the issues you are describing on the throttle side.

In the PIC I posted the control lever is in the full choke position.

 

[garndawg]

Just to make sure you understand what im saying,
when you put the control lever back in, you should of lifted the flat spring steel up.
If you install it without lifting the spring steel, it will cause all the issues you are describing on the throttle side.

In the PIC I posted the control lever is in the full choke position.

Yes, I can confirm the flat spring is positioned like yours is in the pic. In your pic, my problem area is just outside your pic in the upper right hand corner.

It's odd, everything looks right and acts right until I install the airbox. Then, when the control rod is rotated to the "choke" position, the bump in the control rod lifts the 90 deg section of the throttle linkage up until it binds on the airbox. On one side of the linkage, the control rod is lifting, on the other side, the small square molded bump in the bottom of the airbox is pressing down. Pressing the control rod down into 'choke' creates a clockwise flex in the throttle linkage, which provides the force to flip the control rod back into the 'run' position when released.

That bump on the airbox is there for a reason, but I just can't figure out what I'm doing wrong.

 

[walterg]

Only other thing I can think of is, you have to squeeze the throttle before you can put it in the full choke position.
Just trying to cover all bases.

 

[garndawg]

<facepalm>

I. Am. So. Stupid.

 

[benj180]

Just wanted to say thanks for this, even 8 years later as I was doing the exact same thing!!