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Engine Help => Kohler Engines => Topic started by: leadslead on November 21, 2013, 06:12:23 PM

Title: Ch25s v-twin
Post by: leadslead on November 21, 2013, 06:12:23 PM
So I just picked up a hor kohler 725cc what do I have to do to give it more hp ..thing wights a ton 1.?? Crank
No nothing about thies motors b&s easy but kohler no idea any info would be help full .. As for carb are they all single barrel ??
Title: Re: Ch25s v-twin
Post by: catfishdan on November 22, 2013, 01:36:03 AM
the 30hp twin is same block but runs 2barrel carb and intake. you will be suprised what these engines will do even with minimal work. they are heavy but when you look at parts you wilm understand why. they are built last
Title: Re: Ch25s v-twin
Post by: leadslead on November 22, 2013, 04:14:13 AM
Yea been in side a ole single ..... Yea very heavy so.  What would be a mild build  cam rods ... 30 hp dual carb
Title: Re: Ch25s v-twin
Post by: catfishdan on November 22, 2013, 05:07:19 AM
rods/pistons
solid lifter stock cam
valve springs
adjustable rockers
flywheel
good clean up of ports on heads
30hp carb and intake

cheap mild build that will be very reliable and perform well
Title: Re: Ch25s v-twin
Post by: leadslead on November 22, 2013, 07:23:56 AM
Stock pistons no good ???
Title: Re: Ch25s v-twin
Post by: catfishdan on November 22, 2013, 08:34:30 AM
they have huge dish. best to go with aftermaket
Title: Re: Ch25s v-twin
Post by: beezerboy on November 24, 2013, 02:54:51 AM
can you give us an approximate on the volume of the dished part on the stock piston?
Title: Re: Ch25s v-twin
Post by: flatlanderfornow on November 24, 2013, 05:06:52 AM
A graduated syringe and some rubbing alcohol will tell you very quickly. Make sure what
you're measuring is flat, put a measured quantity in the syringe (available at veterinary
supply places), fill the area to be measured till it JUST comes out, read what's left in the syringe,
and do the math.  Very helpful to know how to do this, works for heads as well and
allows you to cut them yourself and get them both the same.  6" tabletop belt sander works good
for cutting the heads down-thanks Paul!
Title: Re: Ch25s v-twin
Post by: PJG56 on November 24, 2013, 06:34:54 AM
A graduated syringe and some rubbing alcohol will tell you very quickly. Make sure what
you're measuring is flat, put a measured quantity in the syringe (available at veterinary
supply places), fill the area to be measured till it JUST comes out, read what's left in the syringe,
and do the math.  Very helpful to know how to do this, works for heads as well and
allows you to cut them yourself and get them both the same.  6" tabletop belt sander works good
for cutting the heads down-thanks Paul!


Your welcome Todd.
Title: Re: Ch25s v-twin
Post by: leadslead on November 24, 2013, 07:24:58 AM
Any way to shave weight off thies things like 50 lbs worth or are they just heavy no matter what
Title: Re: Ch25s v-twin
Post by: beezerboy on November 24, 2013, 02:36:29 PM
ya well, thanks, but I kinda all ready know how to measure them.... mine are unfortunately still in the engine at the moment. I'm just trying to do some planning before I tear it down (or not). anybody have some numbers? aprox is close enough to do some projections. thanks
Title: Re: Ch25s v-twin
Post by: flatlanderfornow on November 26, 2013, 05:29:54 PM
I got a pair out in the barn I'll measure this weekend if you don't mind waiting that long.
Title: Re: Ch25s v-twin
Post by: beezerboy on November 26, 2013, 10:22:07 PM
ya, nice! very helpful to know that
Title: Re: Ch25s v-twin
Post by: flatlanderfornow on November 27, 2013, 05:02:34 PM
Be best of course to make the volume 0 ;)
Title: Re: Ch25s v-twin
Post by: leadslead on December 08, 2013, 05:23:09 PM
If u put aluminum flywheel on gotta do any thing different with fire box be sides chuck it ???can u use same coils ??
Title: Re: Ch25s v-twin
Post by: cycloneracer on December 08, 2013, 05:49:26 PM
Zach Kerber builds a billet flywheel that uses the stock coils.

Link in my signature.
Title: Re: Ch25s v-twin
Post by: leadslead on December 08, 2013, 06:17:03 PM
Yea I got his number just haven't called yet
Title: Re: Ch25s v-twin
Post by: leadslead on December 12, 2013, 04:43:40 PM
What can I expect out of stock cam 4500 then noise after ?????those suckers are a lot off cookie dough to build
Gotta do it a little at a time so rods & wheel what's next after that for quick hp gain