854 hood vs 702 hood

[clueless 2,989]

I know the 854 hood is longer to accommodate the K181, but is the frame longer than my 702? I have a 702 and I'm thinking about putting a K181 on it and find a 854 hood to put on it.

[Pullstart 62,849]

I have never owned an 854, or the hood from one, but I loaned my front hanging weight to @PeacemakerJack and @Coulter Caleb for a plow day one year and it did not fit as easy near the bottom of the hood as it did my 502, sporting a ‘64 frame (604?) The frame holes were all the same however, but we never measured the length of the frames.

[Achto 27,570]

1 hour ago, clueless said:

I know the 854 hood is longer to accommodate the K181, but is the frame longer than my 702?

 

I believe that the frame is the same length. Diggin' deep into my memory bank here so I might be wrong, but I think that the lower mount on the hood is different to accommodate the longer hood.  I do know this for certain: The only reason that the hood is longer on a 854 is to make room for the thicker air cleaner on the K181. If you run a narrower air filter from a K161 you will not need the longer hood. The narrower air cleaner will not effect the way that the engine runs at all.

 

Edited February 13, 2023 by Achto

[squonk 41,099]

[Pullstart 62,849]

1 hour ago, Achto said:

the lower mount on the hood is different to accommodate the longer hood.

That might have been it!  The hood was long enough to interfere or almost at least with the hanging weight!

Picture for home made weight reference…

 

 

 

[Handy Don 12,217]

1 hour ago, Achto said:

f you run a narrower air filter from a K161 you will not need the longer hood. The narrower air cleaner will not effect the way that the engine runs at all.

Sorry @Achto, but I’m convinced that if there was no difference in performance then Kohler would not have used the larger air cleaner and WH would certainly have avoided the expense of the unique hood and altered hood mount. The smaller air cleaner significantly lessens the amount of permeable area of the filter. As the filter gets dirty, the difference would be even more pronounced.

I’ll grant that many users may never notice the difference, depending on how they use their tractor.  

Edited February 14, 2023 by Handy Don

[Pullstart 62,849]

I’d love to find a K161 filter element for Putt Putt.  I just crush a 2” K-181 element until the hood fits!  

[Handy Don 12,217]

4 minutes ago, Pullstart said:

I’d love to find a K161 filter element for Putt Putt.  I just crush a 2” K-181 element until the hood fits!  

Even with throttling the air intake from 8hp back to 6hp (?) when it’s wide open is still better than the original 5hp, right?   

[Pullstart 62,849]

6 minutes ago, Handy Don said:

Even with throttling the air intake from 8hp back to 6hp (?) when it’s wide open is still better than the original 5hp, right?   

Honestly, my butt dyno has never felt the difference…

[ri702bill 8,318]

13 minutes ago, Pullstart said:

I’d love to find a K161 filter element for Putt Putt.  I just crush a 2” K-181 element until the hood fits!  

I have used both a NAPA gold @squonk?? and a Fram round filter for a Cub, if my feeble memory serves me correct to replace the OE K161 filter...

[squonk 41,099]

The 8 filter is  smaller diameter but thicker . 7 filter is thinner but a larger diameter. Filter area is probably close to the same.

Edited February 14, 2023 by squonk

[ri702bill 8,318]

2 minutes ago, Pullstart said:

Honestly, my butt dyno has never felt the difference…

Seat o' the pants - wait for the dance. Often teamed up with the calibrated Eyecrometer....

[Handy Don 12,217]

1 hour ago, squonk said:

The 8 filter is  smaller diameter but thicker . 7 filter is thinner but a larger diameter. Filter area is probably close to the same.

Hmmm. I think that’s an optical illusion!

The filter specs I found had both filters at 4⅜" OD, 3” ID.

K181 is 2⅜” H

K161 is 1½” H (⅞” shorter)

So about 37% less filter surface--a non-trivial reduction.

Again, if a shorter but otherwise equivalent air cleaner had been available, I gotta believe it would have been used.

And, again, short of a dyno test or other side-by-side comparison at max loading, probably hard to discern. 

 

[Pullstart 62,849]

6 minutes ago, Handy Don said:

hard to discern

The amount of times my engine has actually hit the governor, is very limited.  Even while plowing, I feel like the K-181 could work harder if it wanted or needed to.  

[Handy Don 12,217]

1 minute ago, Pullstart said:

The amount of times my engine has actually hit the governor, is very limited.  Even while plowing, I feel like the K-181 could work harder if it wanted or needed to.  

Yep. Even 6hp is a lotta giddyap! Most of us never come close to really taxing our engines. 

I’ve never even been able to bog down the 6hp Tecumseh in my Lawn Ranger, though I have gotten it into the governor when pushing a blade load of gravel! The sound just gets a bit lower and louder. Not nearly as neat as the low snort Kohlers make when the governor kicks in!

[Racinbob 11,075]

I'm with the 'just put a K-161 filter on it' group. You'll probably need the K-161 cover too or modify the larger cover. The free air opening between the cover and the back plate is the same. You certainly won't throttle the engine back to 7hp. If the engine isn't getting enough air it will tell you. If you're concerned just keep alert to any signs of it running rich. You won't. 

Edited February 14, 2023 by Racinbob

[Handy Don 12,217]

8 minutes ago, Racinbob said:

 The free air opening between the cover and the back plate is the same.

Yes, the free air gap is the same but that is NOT the constraint on the airflow, which is the amount of filter element between the top and bottom rubber edges. That gap is at least ⅓ smaller.

Sure, it’ll run. Probably a bit rich unless you back that out at the carb. But it simply won’t breathe the same and is no longer capable of the full rated power at WOT (wide open throttle).

For a lot of users (maybe most), that reduction at the top end probably doesn’t affect how they use their machine but it is real. There is a reason NASCAR mandates restricter plates!

[pfrederi 17,738]

Looking at the K181 parts manual some spec numbers use the same air filter part number as the K161s...So I guess Kohler wasn't overly concerned.  Besides the amount of dirt in the filter probably makes for bigger variance in air flow than the size difference.

[Racinbob 11,075]

Very true Paul

Don, restrictor plates are on the 'bottom' side of the carb (when they used them). Similar theory but different. Engines with plates tell the carb they don't want as much air/fuel mix. Chokes are on the 'top' side and enrichen the mixture when needed. I like the idea of more filter media though. 

 

[Handy Don 12,217]

1 minute ago, Racinbob said:

Don, restrictor plates are on the 'bottom' side of the carb (when they used them).

Aha! So I learned something new today, thanks.

(I know I’m beating a dead horse here, but I have a lot of respect for the Kohler and WH engineers and designers so if they put in a distinction, it was for good reasons.)

[pfrederi 17,738]

Also maybe Kohler was trying to simplify.  The K 181 and the big blocks used in many spec the same air filter.  A K181 has only 10% more displacement to fill with air so why would you increase the air filter capacity by 37%..  Maybe so it could also work on big blocks???