Kohler 18 HP into a 20 HP??? same bore and stroke what do i need to do?

[spookum]

Hi guys! happy holidays. The kohler 18 HP and the 20 HP are the same bore and stroke (the 23 HP is a bigger bore... he he he) I think i may have a bead on a kohler that is in my price range. I looked up parts numbers and i cant find any discrepacies. So tell me, is it the carb? is it the exhaust? is it the timing? is is the cam? if i have to rebuild an 18 may as well make it a 20 right???? Thanks in advance and what are the part numbers?

[Hogneck]

Hi guys! happy holidays. The kohler 18 HP and the 20 HP are the same bore and stroke (the 23 HP is a bigger bore... he he he) I think i may have a bead on a kohler that is in my price range. I looked up parts numbers and i cant find any discrepacies. So tell me, is it the carb? is it the exhaust? is it the timing? is is the cam? if i have to rebuild an 18 may as well make it a 20 right???? Thanks in advance and what are the part numbers?

What is the displacement for 23HP? 18hp is 570cc I believe.

[spookum]

18 and 20 hp are 627cc...

[msafi65]

J dont you sleep? Idd print the parts pages for both engines and compare #s. I think its the carb. Guess who has a new 20hp carb on the shelf. 20hp mag. mod #M20S Spec #49521 Serial #2020110876 This one is a couple years newer than yours but will work. Merry Christmas

[Hogneck]

J dont you sleep? Idd print the parts pages for both engines and compare #s. I think its the carb. Guess who has a new 20hp carb on the shelf. 20hp mag. mod #M20S Spec #49521 Serial #2020110876 This one is a couple years newer than yours but will work. Merry Christmas

To whom are you referring about sleep? I worked midnights and am not smart enough to stay outta the garage and goto bed before I go back in for another one.
Would the 20 hp carb be for a Vangard? if so it should fit the 18hp I run with (2001).

[msafi65]

The carb is for a kohler magnum 20. I look at post times and see all hours day n nite. Spookum is building a magnum from parts.

[spookum]

goin to have to look at this deeper in detail, maybe even down in oregon! and as a side note, the max fired up, idled for a minute, then died. I was out of jumper pack so i had to call it quits. Oh well, it suprised me how easy it started!

PS im such a nite owl, especialy when i get a bright idea that wont allow me to go to sleep!

[spookum]

kohler 18 and 20 HP cam shaft part number: 82-755-13-S

kohler 18 HP carb: 52-853-23-S

kohler 28 HP carb: 52-853-27-S so very very close, and yet so far away!

governers are the same

looks like when i get back from oregon, i need to find out if they are the same carbs, as they are diffrent part numbers. how ever, number "3" and "11" are the same for both carbs . This means that the inflow and out flow have to be the same? i cant see having diffrent carb housings and the SAME gasket sets. what do you think oh wise buffalo truck buddy?

carb.jpg

[msafi65]

The carb body is is the same. It think the flow rateis different. We can check the bore size.

[spookum]

sounds good! If the bodies are the same, hopefuly it is the needels, i just hope like heck it isnt a venturi some where.... that would not be fun. Slapping a pair of calipers on a 18 hp and the 20 hp will tell the tale fast enough! Thanks for all your help!

but Kohler still calls for different part numbers? kind of weird!

merry x-mas... and yes, the only reason im up THIS early is because iv been up all night

[clasicplug]

Hi I have a 1990 18 HP Kohler in a 8x8 Argo. Could you let me know how it worked out with the carb as I might rebuild my engine and if I can play with the carb to get more HP now would be the time to do it.

[spookum]

welcome to the forums clasicplug. when i get more information, ill let you know. probbably in a few weeks. make sure that you subscribe to this thread so it will email you wen i post again! you could also go down to the local kohler dealer/mechanic in your neck of the woods. They should be very knowledgleble, and if you find out before i do, let me know.

[clasicplug]

Thanks for the reply spookum. I'll see what I can find out.

[spookum]

Yah, i have taken it as far as i can with out sitting down with a pair of calipers to compare the actual interior bore size on the carb. Bolth sides need to be measured, the intake and the out side. They are *diffrent* part numbers, how ever it could be that they are actualy the SAME carb bodies (as evidenced by the exact same gasket sets for mounting.) I dont want to have to spend money on a new carb body to get 20 HP if all it is is jetting! The cams are the same for sure, along with the valves. All it can be then, is the way the machine "breaths" The 20 HP kohler is just some how getting more air/fuel than the 18 HP!

----->>>Friggin public computer!!! i hate adds.... if there was a way to get rid of it, i would!!!!!!! im sorry to all who view this post!<<<---------

i killed it

[msafi65]

Hey Spookum I found a complete Magnum manual available throught the databases in the local library. I downloaded the manual and the 18 hp shows 691cc and the 20hp 769cc. Same bore different stroke. Dont know if the carb swap will help or not .