Kohel kt series question

[Ex wh1257 61]

Hello everyone, I just had a question about a Kohler KT 17 engine. I would like to convert it to a KT 19 engine. Now my question is whether the crankshaft is the same thickness. I already know that the bore is the same and I found out that the connecting rod a 19 hp engine is shorter than a 17 hp engine, this is the only difference, wondering if anyone can help me with the correct information

[Ed Kennell 41,765]

I don't have an answer to your crankshaft question, but I am curious as to what else is different between the 17 and 19 HP engines to create the additional 2 HP?

[953 nut 59,716]

5 hours ago, Ex wh1257 said:

connecting rod a 19 hp engine is shorter than a 17 hp engine

The connecting rods is shorter on the 19 HP because the throw of the crank is longer resulting in 6.7 : 1 compression ratio as compared to the 17 HP having 6.0 : 1 compression. Crank and rods are the only difference.

[Ed Kennell 41,765]

2 minutes ago, 953 nut said:

throw of the crank is longer

Thanks Richard.  So the block and head are the same.

[953 nut 59,716]

18 minutes ago, Ed Kennell said:

Thanks Richard.  So the block and head are the same.

Everything on the K Twins is interchangeable except the crank and rods. I just looked it up, the crank throw on the KT- 17 is 2.75 and on the 19 it is 3.062. The magnum twins run a bit lower compression ratio  and the heads have a different part number which probably is the reason for the lower compression.

[Ex wh1257 61]

6 hours ago, 953 nut said:

Everything on the K Twins is interchangeable except the crank and rods. I just looked it up, the crank throw on the KT- 17 is 2.75 and on the 19 it is 3.062. The magnum twins run a bit lower compression ratio  and the heads have a different part number which probably is the reason for the lower compression.

so the conclusion if I want to change it I need a different crankshaft and different connecting rods, the connecting rods alone are unfortunately not enough

[Ed Kennell 41,765]

4 hours ago, Ex wh1257 said:

so the conclusion if I want to change it I need a different crankshaft and different connecting rods, the connecting rods alone are unfortunately not enough

Yes, I was sure only changing to a shorter rod would actually decrease the compression and the HP. 

Richard had the answer that the larger throw of the KT19 crankshaft is what increases the stroke, the compression and the HP.

Edited April 17, 2024 by Ed Kennell