pole saw issue, low speed... gear reduction head?

[toadman]

I just recently picked up a stihl HT56-c pole saw... It appears to have the same motor as my fs56 string trimmer, but holds less fuel & feels to run at far lower top end RPM.
I am curious, I played around with the pruner head and found it's geared down a fair bit... Does anyone know the differences between the two motors?
Their both listed as having the same HP & displacement, they both share a partial model number and several casting numbers.
The carb part number is different, but appears to mount the same...
Ignition coil is the same, as is the flywheel & shaft clutch, most of the plastics, and the air filter assembly.

My main question is, does anyone know if there's a reason they dropped the RPM?
it's limited down about 3k slower than the weedeater motor.
Both 4-stroke nicely on the top end & idle well, run smooth, and clean out under load as intended, so I am fairly certain it's not a tuning issue.
I don't believe it's limited by the coil, as it's the same part number as my string trimmer which turns a 3k rpm faster.

Would it harm anything to swap over to a weedeater carb for a little more cutting speed, or am I missing something?

it's not a shaft resistance issue, I removed the shaft from both motors out of curiosity and it changed nothing for the run speed. (<100rpm change)

It runs well, exceptionally quiet & has a surprising amount of torque for the little chain, but very slow chain speed.

 

[SteveSr]

I would think that they would be the same exact engine. You likely have a carb or clogged spark screen issue.

 

[DND 9000]

The engine and the components of the engine are the same on the FS 56 and HT 56 in general. Maybe you don`t have the same components in both of your machines, because of different age and revision stages.

 

[toadman]

I would think that they would be the same exact engine. You likely have a carb or clogged spark screen issue.

I only have a couple hours on the pole saw, I bought it new...

The engine and the components of the engine are the same on the FS 56 and HT 56 in general. Maybe you don`t have the same components in both of your machines, because of different age and revision stages.

did they change the trimmer motor as well?
It would seem that the RPM the pole saw motor runs at would be pretty ineffective as a string trimmer without redoing the head gearing...

 

[HarleyT]

Same carb too.

 

[SteveSr]

I only have a couple hours on the pole saw, I bought it new...

Sounds like you need to take both of your tools back to the dealer and ask for an explanation. Sounds like something isn't right with the HT56 pole saw

 

[DND 9000]

did they change the trimmer motor as well?

When there are changes made, the complete series gets normally the changes. Maybe your pole saw engine isn`t right or it needs to be tuned. Best would be to have it checked at your local dealer. Both engines (on the trimmer and the pole saw) have the same rpm specification.

 

[HarleyT]

Just for the hell of it, swap powerheads, Just takes loosening 5 screws on each power head.
See if it runs the same, if not, or what. Gives you more info.

 

[toadman]

Just for the hell of it, swap powerheads, Just takes loosening 5 screws on each power head.
See if it runs the same, if not, or what. Gives you more info.

I am going to try this, I am super curious!!

 

[HarleyT]

I am going to try this, I am super curious!!

Yeah, then after that, swap the cutting heads. That would help determine if your problem may be in the shaft area.

 

[HarleyT]

Anything noteworthy?

 

[toadman]

Yah, the weedeater motor spun 3k higher on the polesaw, and cut very well, while the polesaw motor barely cuts grass.

 

[Ax-man]

I have one of those pole saws also . Just curious what you came up with for max rpm's at WOT??? I had to screw around with the carb settings several times on mine before I finally got it dialed in to get it where I liked it. It wasn't the cutting speed of the head but more getting that engine to start and accelerate to WOT after a brief warm up and run like a two stoke should run.

If I remember right mine is just under 10K at WOT. It seems like the module has a limiter on it.

I am not crazy about those engines and cussed more than a few of them when I was working on them at my part time job at the Stihl dealer. They are fussy temperamental engines .

I like the pole saw for what I need to use it for and can't complain about the engine or the way it cuts because it was free to me from the dealer as a Christmas bonus because I helped them out so much and I guess they felt I was under paid . I offered to pay but they didn't want my money. If it wasn't for this darn Covid virus I would be working for them again .

 

[toadman]

I got 8500-9k on the pole saw, and 11k- 11200 on the trimmer.
I did figure out the issue, I swapped carbs and the pole saw came alive with the weedeater carb!!!
Swapping motors onto the opposite shafts had no effect on operating RPM of each motor.
I adjusted both carbs, and No matter what I did to the pole saw carb the motor ran the same.
New carb will be in monday.
Same PN as the one on my weedeater, which is older, but has the updated carb.
Dealer is just giving me the new one, apparently it's a known issue to them & several power heads have come back to them running poorly or not at all from that same batch I got.