# Throttle cable mysteriously shrunk



## Slynn (Nov 27, 2018)

Really, my throttle cable didn’t shrink, but my brain must have. Here’s the scenario:

Rebuilding a Stihl BR550 backpack blower and all the fun that entails. I get to the re-assembly and I’m replacing the factory carb with an aftermarket carb.

Everything matches up. Same size, angles, holes, throttle arm height and travel is exactly the same.

Upon attaching the throttle cable to the carb and then putting the cable sleeve in its plastic molded seat, it pulls the throttle wide open. As in, there is no farther a distance that it can travel. It’s maxed. No slack to pull.

Here’s what I’ve checked:
No, the carb isn’t upside down or backwards.

Looking at the other end of the throttle cable: Checking the trigger on the handle shows that the trigger is extended as open as it can go. As in, it’s not locked in the depressed position.

Removing the throttle cable completely from the unit confirms that the cable travels freely. No kinks or twists. Throttle cable does not need replacing.

Close inspection of both the factory and aftermarket carb reveal no magical adjustment screws that allow the throttle arm to travel down and loosen the connection. Also noted in that close inspection- the original carb’s throttle arm travels no lower than the replacement arm currently travels (so no adjustment screw “should” be needed).

So, the throttle cable is the same. Carb is identical to the original. All cables are fitting into their proper routing slots.

Clearly, it’s an operator error on my part, and a super stupid one at that. But for the life of me, I can’t figure out, mechanically speaking, where I’ve gone wrong. I’m sure it will be a duh-huh moment when the error is discovered. Any ideas?


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## Slynn (Nov 27, 2018)

Yes, I searched the forum before posting the question.

Yes, the neck of the throttle cable is completely slid down into the slot and the “knot” is seated fully/flush.


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## geogrubb (Jul 28, 2006)

I would guess it is a routing issue, the cable is going over something when it should be under or vice-versa. Have a good one. Geo


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## geogrubb (Jul 28, 2006)

Check where the cable bracket is attached to the blower tube if it slid forward just a little it could create your problem, I had it happen with a FS85 trimmer. Have a good one. Geo


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## finaprint (Jan 29, 2006)

X2, if the carb linkages are truly the same then any error has to be in the location of the cable HOUSING ENDS, making the cable inner seem to be the wrong length. 

Or an overlooked mistake, the only other way it can happen.


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## Slynn (Nov 27, 2018)

Okay. I tried all of the things and finally cried uncle, bringing it to my $tihl dealer. They told me I have a bad throttle cable and need to replace it. I paid the $25 assessment fee and got my blower back. I can replace the cable myself. I intend to try and rig it up to run anyway, knowing that I need to artificially extend the cable by a half inch. If that doesn’t work, I’ll extract the cable and find out just what made it suddenly become too short. I’ll let you know what the final solution becomes. At least I know I’m not crazy. I did put it back together correctly!!!


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## Milton Fox Racing (May 27, 2014)

Before you remove the old one - check the route again. If it is just a half inch short - it could be going over/around something rather than under/beside something....


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## finaprint (Jan 29, 2006)

The cable rarely frays internally and if strands break they can lock up pulling cable one way. You can tell that by watching both ends to see how much extends out.


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