Kohler CV12.5: Difference iin Output

[charst]

Dear forum

I am currently restoring the 9 horse version of the above engine. It belongs to a JD STX30 lawn mower. I have read that the next larger model (STX38) is equipped with the same engine but has 13 hp output. Does anyone know the differences in the engine configuration? Is it perhaps different valve timing? Different carb?

Greetings from Germany

 

[ajwgator]

See if these answer your questions & welcome to the forum.

The first link for JD STX30 shows a Kohler engine CF12.5-1216-S and the HP at 9hp

TractorData.com John Deere STX30 tractor engine information

and the second for JD STX38 shows a Kohler engine CV12.5-1215 and the HP at 12.5hp

TractorData.com John Deere STX30 tractor engine information

I couldn't get Kohlerengine.com to come up with a manual for those models. Sorry not much help...

 

[charst]

..thanks anyway...

 

[ajwgator]

Charst, I still can't find a place to help you out with the differences, you might try asking some of these guys on this other forum. Even though it is an old post that is now a "sticky" post for a starter problem on a STX38, these guys are still around there. I find this site pretty useful too as I've been a member for some time there.

STX38 Starter Problem Fix - MyTractorForum.com - The Friendliest Tractor Forum and Best Place for Tractor Information

Octoberfest is almost upon us! Wish I could make it this year. Another week till then I think.

Cheers

 

[charst]

Thanks again. I'll give it a shot...

BTW, restoration is complete. Engine starts&runs well (see pics).

 

[ajwgator]

Great looking restoration job! I really like doing that stuff too. Knowing the ins & out of the mechanicals sort of gives one the feeling of being in control of it instead if it being in control of you. Good luck in your quest of learning the differences between the two models. Be sure and share it with us here too and any tips or sites that shed more light on things.

Cheers again
A J

 

[ILENGINE]

I did a part comparison between the two models listed, and found the only major difference is the carb.

 

[silver1]

Thanks again. I'll give it a shot...

BTW, restoration is complete. Engine starts&runs well (see pics).View attachment 27386View attachment 27387

I have a STX38 that is 13Hp, CV13-2150-09, SN=2704516 252, model CV13S. 398cc. There is difference by year/SN/export, etc.
my carb doesn't have the fuel cutoff solenoid. I see that the starter and other things are different .
Nice job on the restore!
Silver1

 

[bertsmobile1]

With most small engine makers, small differences in output power will be a bigger main jet.
It is silly but most mower companies want to start every model line with a "smaller" engine so they can "upgrade" it over the projected production life by fitting a "more powerful" engine.
hus you get blocks of engine outputs usually over a 3Hp range where the difference is nothing more than a bigger carb or in some cases nothing more than a bigger main jet.

 

[charst]

Thank you all for the information provided.
A difference in carburetor size was also my first thought.

I managed to sell that engine a couple of days ago. The new owner is fine with the output since he intends to put it in a STX30.

I also made sure not to get bored during winter and purchased an 1997 JD LX188, with little rust and broken cylinder head gasket (but still running quite nicely) for a very low price.
Will post some before-and-after pictures when the job is done.

Greetings from Northern Germany!