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What magic is Kohler using to get different hp ratings on the same engine? Or….is it a Cub Cadet trickeration?

Probably a different jetted carb, as manufacturers can only advertise engine hp as appropriate. Today’s engines are designated by cylinder size. Changing jet size will change horse power.

Rivets said:

Probably a different jetted carb, as manufacturers can only advertise engine hp as appropriate. Today’s engines are designated by cylinder size. Changing jet size will change horse power.

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Thanks. (edit) 725cc 20hp to 25 hp.

My 651V Kawasaki is rated @ 21.5 Hp, & with carb tweak, it can become 691V @ 23 hp, & again tweaked further, it becomes the 730V @ 24 hp, same bore & stroke. And all 726cc. So mine is living easy imo.

• Displacement​

  726 cc (44.3 cu. in.)

• Bore x Stroke​

  3.1 x 3.0 in. (78 x 76mm)

Kohler did the same thing with the CH18-20-22 engines. The 18 had a screw next to the throttle butterfly lever that limited it to only opening halfway. the 20 had the screw removed which allowed full throttle plate movement, and then the 22 added spark advance smart spark.

Good answer. Even a lot of seasoned Kohler techs don’t know that info.

VegetiveSteam said:

Good answer. Even a lot of seasoned Kohler techs don’t know that info.

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We use to refer to it as the $130 screw because that was the price difference between the CH18 and CH20. But if you removed the screw on the CH18 you voided the warranty.

ILENGINE said:

But if you removed the screw on the CH18 you voided the warranty.

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I wouldn’t have denied warranty if that screw were missing.

VegetiveSteam said:

I wouldn’t have denied warranty if that screw were missing.

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You wouldn't had to make that decision. The Kohler distributor rep that had to sign off on the replacement short block or engine replacement would of had the final say.

As long as there wasn't an engine failure requirement a short block or engine you would of been safe though.

As a dealer no but as a rep I would. Paul and a lot of reps might not even know that screw was there. Typically, they would call me, before I retired, or one of my associates before signing off or denying a warranty. But all reps are different.

7394 said:

My 651V Kawasaki is rated @ 21.5 Hp, & with carb tweak, it can become 691V @ 23 hp, & again tweaked further, it becomes the 730V @ 24 hp, same bore & stroke. And all 726cc. So mine is living easy imo.

• Displacement​

  726 cc (44.3 cu. in.)

• Bore x Stroke​

  3.1 x 3.0 in. (78 x 76mm)

Click to expand...

Not that easy on some of those engines they limit the throttle opening with the lever on the carb throttle shaft. They may also be playing games with hp rating and just call it a different hp than it actually is. They can call it less hp and get by with it but not more hp.

I hear ya, I do know my 21.5hp Kawasaki won't bog down like the neighbors 25hp Briggs when we cut his same grass.

They also slip restrictive gaskets between the carb & the manifold
Honda do that on all of their engines
when carb jet size used to be done you could see from the IPL's that different engnes had different jets but now days looks like they only list a& sell the single largest jet
I came across that when I did a jet replacement on a badly corroded carb and the owner came back wanting to know what I had done because the machine now did things it could not do before

Craftsman use to be bad about listing hp of the engine different than the model no. of the mower have a Kohler that is a CV 20 that the mower said it was a 18.5

hlw49 said:

Craftsman use to be bad about listing hp of the engine different than the model no. of the mower have a Kohler that is a CV 20 that the mower said it was a 18.5

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Most of the ones on Craftsman that I saw were higher HP on the mower than what the engine said. which was the basis for the lawsuit over HP ratings. Craftsman was the primary defendant in the case followed by Briggs. Kohler didn't have to change how they rated their engines since they were not playing the HP game.

Anyone remember the 11, 11.5 12 and 12.5 HP briggs flathead engines that basically identical?

If my memory is any good, those where the engines which got Briggs in trouble and started the questionable hp lawsuits.

There was a lot of shenanigans going around with HP ratings. Craftsman with using higher HP ratings on mower claiming to use a different rating system. Like the hood said 23 hp but the Kohler command under the hood was a CV22. Briggs the engines listed above but also a case of a customer having a MTD mower with a 4.25 hp engine on his mower. the problem was there was also a 3.75 sticker under that sticker and was found when the top stick came loose. Heard a case of a Toro dealer ordering his spring stocking order and the model listed 17.5 hp Briggs engines but when they arrived had 15.5 HP engines. And when the dealer inquired about the engine change was sent replacement 17.5 HP stickers to replace the 15.5 on the engines.

I remember those stickers. Lucky the dealer I worked for only had four of those units.

CV20 off that Craftsman now sits on my 2000 X1901 Dixie Chopper

Rivets said:

If my memory is any good, those where the engines which got Briggs in trouble and started the questionable hp lawsuits.

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IIRC, Briggs was ordered to pay some money to owners, who bought the machines in the suit..

ILENGINE said:

Kohler did the same thing with the CH18-20-22 engines. The 18 had a screw next to the throttle butterfly lever that limited it to only opening halfway. the 20 had the screw removed which allowed full throttle plate movement, and then the 22 added spark advance smart spark.

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That's interesting. Side note, back in the late 1960's, Pontiac did the very same thing to the Firebird's 4 barrel carbs so the GTO with the same engine/transmission as the Firebird, would be a bit faster. They did it with the linkage to the rear barrels.

Back in the 80's they were putting BOP engines in chevy cars and then they put chevy engines in BOP cars. My mother had a Bonneville with a 400 Chevy motor in it and a friend had a monte carlo with a 3.8 BOP engine. Fun getting the right oil filter.

Hammermechanicman said:

Back in the 80's they were putting BOP engines in chevy cars and then they put chevy engines in BOP cars.

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I remember that.....

SamB said:

That's interesting. Side note, back in the late 1960's, Pontiac did the very same thing to the Firebird's 4 barrel carbs so the GTO with the same engine/transmission as the Firebird, would be a bit faster. They did it with the linkage to the rear barrels.

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Little more to it than just the carb linkage. 400CI Pontiac engines 1967 and up used the same block, but offered some different HP ratings for GTO, Firebirds and other models - such as HO and Ram Air type optional engines. All had 4 barrel Quadrajet carbs but used higher performance heads, intake manifolds, exhaust manifolds, and cam shafts, etc. May all look the same on the outside, but they are different.

This brings up a question I've had. What are typical jet sizes for Kohler and Briggs single lung engines. I have carbs that all look the same but some will surge and need the jet opened. I increase till it levels out, but would like to know what good sizes are.

I start will a #80 drill and work up. When I have to punch a jet the largest drill size I use is a #77 drill. That would be .018“. I do remember using a number drill #76, .020“, but I found out the hard way that it may be too much. Now I only do this if I have a spare jet on hand. I should add that the material used in today’s jets is not the same as when I started in the ‘70’s. I’ve found some to be harder and some softer. Anyone who attends punching jet nowadays should be prepared to purchase a new jet or carb before attempting to do this. Voice of experience.

Rivets said:

Anyone who attends punching jet nowadays should be prepared to purchase a new jet or carb before attempting to do this. Voice of experience.

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Thanks Rivets- Good advice.

I read this thread and am getting more confused.
Any expert info on this engine would be appreciated.

I have a 725cc Kohler on my 2008 727T6 Grasshopper that is supposedly 27hp .
DISPL (CC) 725
MODEL NO. CH740S
SPEC NO. CH740-0096
SERIAL NO. 371990010x
BUILD DATE 07/18/2007

IS it really 27hp, and can I re-jet or tweak it to get more hp?