K341 balance gears- back to back test

[Greentored 3,214]

This is a topic of much debate, so thought id share some first hand experience with these gears and vibration.

The 1277 'lawn duty' got a K341 swap late last fall, and although the extent of his work was blowing leaves and a neighborhood ride, have not been able to get this 'balance gear' thing out of my head. Great runner, no smoke, nice n quiet, but is there a ticking time bomb inside that could potentially destroy a good 16hp block without warning?  Yesterday I pulled the engine back off, flipped it over, and went inside.

The wear was SCARY! I could rock and wobble the gears all over the place, and the teeth were worn sharp- Gonna call this a real good catch!  I popped one gear out, split the second with a long chisel, fished the pieces out, and slapped her back together.

The result: there is absolutely, beyond a doubt, a noticeable difference in vibration across the board, most noticeable at about 2000rpm. Overall, not any worse than a non counterbalanced K series big block- 'bouncy' at idle and just fine right up to 3600, but if someone were to run this at 2 grand I believe it would get 'buzzy' and uncomfortable.

Some of you guys are much more well versed with these and can chime in with your experiences, but after this back to back test, personally speaking, I will continue popping them out of my used engines with unknown hours/history, but if the time ever comes to overhaul a big K341, I would probably install new ones, just because of that 2000rpm range.

Hope this ends up being some useful information for someone

[pfrederi 17,741]

Both the K301 and K321 i have overhauled and removed the gears had that buzziness that wasn't there before hand.  A K341 also has it but I had not used that engine before rebuild so i can't say for certain removing the balance gears did it.

[ebinmaine 67,627]

Correct me if I'm wrong here but it seems I've only been hearing about the 341 having the exploding gear issues...

 

Is that correct or have I just not heard about the others yet?

[Greentored 3,214]

18 hours ago, ebinmaine said:

Correct me if I'm wrong here but it seems I've only been hearing about the 341 having the exploding gear issues...

 

Is that correct or have I just not heard about the others yet?

The little bit of online digging, it does seem to maybe be more of an issue with the 341s. Perhaps just because they all (I think?) had them, whereas the 10-14s could be found with or without? Maybe someone here can set us straight on that.

[pfrederi 17,741]

INteresting. 

 

K-341 had 15 variants with balance gears, K321 26 variants, K301 15 variants and K241 4 variants.  I have found one WH spec 301 with out balance gears.  I am still curious if failures are more common with old style gears and if that is why they were redesigned....

[ebinmaine 67,627]

19 minutes ago, pfrederi said:

am still curious if failures are more common with old style gears and if that is why they were redesigned

Forgive me if this has been brought up already. Do you know the physical differences between old and new style?

Like is one nylon, or shaped different, something like that....

[pfrederi 17,741]

3 minutes ago, ebinmaine said:

Forgive me if this has been brought up already. Do you know the physical differences between old and new style?

Like is one nylon, or shaped different, something like that....

 

[squonk 41,155]

Trying something here. Don't know if it will work. Loose balance gear on my K341.

 

https://photos.google.com/share/AF1QipPxLtDwCuxwmWLzvpSRmsRXh1MRSWNpQsAoymZGU5oodXYjxVFCWCKri8Z9iFH-GA/photo/AF1QipNNz5ZvsvvxKLe-5Lxm6ywAeAtgIcLTOKiEOHf2?key=dFpqVE83d3NxOGVaX2NmYkdvNHpObmNQUEY1dFN3

[Bill D 1,926]

On 3/29/2021 at 9:53 AM, Greentored said:

This is a topic of much debate, so thought id share some first hand experience with these gears and vibration.

The 1277 'lawn duty' got a K341 swap late last fall, and although the extent of his work was blowing leaves and a neighborhood ride, have not been able to get this 'balance gear' thing out of my head. Great runner, no smoke, nice n quiet, but is there a ticking time bomb inside that could potentially destroy a good 16hp block without warning?  Yesterday I pulled the engine back off, flipped it over, and went inside.

The wear was SCARY! I could rock and wobble the gears all over the place, and the teeth were worn sharp- Gonna call this a real good catch!  I popped one gear out, split the second with a long chisel, fished the pieces out, and slapped her back together.

The result: there is absolutely, beyond a doubt, a noticeable difference in vibration across the board, most noticeable at about 2000rpm. Overall, not any worse than a non counterbalanced K series big block- 'bouncy' at idle and just fine right up to 3600, but if someone were to run this at 2 grand I believe it would get 'buzzy' and uncomfortable.

Some of you guys are much more well versed with these and can chime in with your experiences, but after this back to back test, personally speaking, I will continue popping them out of my used engines with unknown hours/history, but if the time ever comes to overhaul a big K341, I would probably install new ones, just because of that 2000rpm range.

Hope this ends up being some useful information for someone

How is the vibration in your rebuilt K321 with the rebalanced crankshaft?  I believe the K321and k341 used the same crankshaft.  My vote is to leave out the balance gears and rebalance the crankshaft.  Bill

[richmondred01 2,237]

I leave them out of my rebuilds. If the customer is concerned about vibration issues, which I really on see in the m16, I advise that the crank, and or, flywheel be balanced. 
This is mostly an issue for the pullers. 

[Bill D 1,926]

4 minutes ago, richmondred01 said:

I leave them out of my rebuilds. If the customer is concerned about vibration issues, which I really on see in the m16, I advise that the crank, and or, flywheel be balanced. 
This is mostly an issue for the pullers. 

You two should work together.  You can send Scott your crankshafts to be balanced at his machine shop.  Have you ever installed one of David Kirk's balance plates in one of your rebuilt M 16 engines?

Edited March 30, 2021 by Bill D

[Gregor 4,846]

It's a garden tractor, Shake, rattle, and roll, is part of the fun. If I ever do one. They will come out.

[richmondred01 2,237]

9 minutes ago, Bill D said:

You two should work together.  You can send Scott your crankshafts to be balanced at his machine shop.  Have you ever installed one of David Kirk's balance plates in one of your rebuilt M 16 engines?

I haven’t used David’s balance plates. 
However, I have heard good things about his products.

 

Edited March 30, 2021 by richmondred01

[Greentored 3,214]

23 hours ago, squonk said:

Trying something here. Don't know if it will work. Loose balance gear on my K341.

 

https://photos.google.com/share/AF1QipPxLtDwCuxwmWLzvpSRmsRXh1MRSWNpQsAoymZGU5oodXYjxVFCWCKri8Z9iFH-GA/photo/AF1QipNNz5ZvsvvxKLe-5Lxm6ywAeAtgIcLTOKiEOHf2?key=dFpqVE83d3NxOGVaX2NmYkdvNHpObmNQUEY1dFN3

My gears made yours look like a brand new engine. Wish I had taken a video.

...and the thing was not making noise! I simply did it for peace of mind.

Think we both somehow managed to get a pin back in a couple grenades.

Edited March 31, 2021 by Greentored

[Greentored 3,214]

23 hours ago, Bill D said:

How is the vibration in your rebuilt K321 with the rebalanced crankshaft?  I believe the K321and k341 used the same crankshaft.  My vote is to leave out the balance gears and rebalance the crankshaft.  Bill

Definitely still know its a big thumper, but it vibrates MUCH less than a standard K series, especially at rpm. Not as smoothe as a counterbalanced engine below about 2 grand, and probably smoother at 3600-3800.

The front end still bounces up and down while spinning her over to fire up, which is kinda cool

 

 

[Greentored 3,214]

The thing to keep in mind is, a single cylinder engine will never be balanced perfectly. Without getting super technical, the counterweights on the crank are designed to offset the up and down motion of the piston and rod.

Thats great for up and down, but now when those counterweights are at 3:00 and 9:00, there is nothing to offset that (well, the big end of the rod does, which is much lighter than the entire piston/rod, but lets keep it simple)

SO- if the counterweights match the piston/rod weight, there is little vibration 'up and down', but a serious imbalance 'back and forth'.

Making the counterweights lighter lessens the 'back n forth' imbalance, but makes the 'up and down' worse.

The goal is to balance (no pun intended haha) the up/down and back/forth vibrations and make them as equal as possible, thats the best one can do without adding a balance shaft, gears, etc....

Kohler seemed to have favored light counterweights, meaning less back/forth at the expense of more up/down vibrations. My guess is this was not by accident- perhaps the up/down was thought to be less perceived by the operator? Or maybe easier on parts? I dunno.....