K301 vs K321

Thu Nov 14, 2013 1:58 pm

I'm sure one of you guru's know the answer to my questions. (I could spend hours looking up online) If I were to find a K321 engine, having a starter-generator, what are the possibilities that the components off my K301with a geared starter and charging system fitting? Concerned with starter mount, back plate, flywheel, oil pan.. Yes Cadet application. Thanks!

Re: K301 vs K321

Sat Nov 16, 2013 12:34 pm

Don't know for sure, never tried changing over all of the the parts mentioned. But, basically the same engine block, so, thinking, if you wanted to go through the process, should work.

My thought, if the K321 had the starter/generator attached, I wouldn't bother, just use the S/G.

Another thought. If the K301 needs to be rebuilt, cheapest way to go.

I have two narrow framed Cub Cadets that have been upgraded to the K321. The two additional horsepower makes for a nice performance increase. One of the K321s had a K301 shroud and engine serial number tag. I didn't know it was a K321 until I rebuilt the engine.

Re: K301 vs K321

Sun Nov 17, 2013 6:55 am

I'm lost, again. I thought the 301 and 321 both used the same starter.

Re: K301 vs K321

Sun Nov 17, 2013 9:29 am

randallc wrote:I'm lost, again. I thought the 301 and 321 both used the same starter.
Single cylinder Kohler engines, including the K 301 and K 321, have several different starter systems: starter/generator, compact starting motor (bendix) two different mounting styles, and two different makes of retractable starters.

Re: K301 vs K321

Mon Nov 18, 2013 4:17 pm

Thanks, guys. My CC is a quiet line, so the starter/gen probably won't fit within the side shields.. I never had a warm, fuzzy feeling about them anyway..
My K 301 was bored 40 over last time I rebuilt it. and have pulled the guts out of it with a 50' deck ever since.. It could use more HP, for sure. Maybe a balanced single would be better, though... less vibration... Thanks again!

Re: K301 vs K321

Mon Nov 18, 2013 5:08 pm

You're not wrong. All of the K-series engines used the same starters, when in Cub Cadets. Your difference is that your looking at an older K-321 engine block than the K-301 AQS engine in your quiet line tractor. The older engines on Cub Cadets used the Delco starter/generator. The newer AQS Kohler K-series engines used the flywheel driven Bendix style starter, with a stater around the flywheel as the generator.

I think that most of your parts will switch over, as the blocks are both the same, and as a matter of fact, the 301 and 321 blocks are virtually identical, except the 321 is bored bigger. There are some other minor changes between the old and AQS engines, including compression release at startup, but some of the older K-series engines even had that, so it's hard to tell if your older 321 block will have it or not. One thing that may be a problem is the bolt holes on the side of the block where the starter generator bracket is, and where you will need the Bendix starter to bolt to the block. I think they are the same holes, but without seeing one side by side, I cannot be certain.

Another change is the fully enclosed tin work and exhaust "box" on the newer AQS engines, which made up part of the "quite line" specs. I'm not sure that all of the tin work will bolt up on the older engine, as I don't think all the holes are present on the older engines. Again, I'd have to see them side by side to be sure.

Regardless, I'd still go for the higher hp engine if you're trying to run a 50" deck. You'll need it!

Re: K301 vs K321

Tue Nov 19, 2013 7:43 am

No worries about the exhaust box and tinwork... That stuff vibrated to pieces decades ago. Yes, I've replaced numerous isomounts and pilot bearings to keep her smooth!
I appreciate the info!
Regards, Stan

Re: K301 vs K321

Wed Nov 20, 2013 7:07 am

Did you sleeve the 301 that you bored to .040?
I have one that was bored at 020, but with the scratched cylinder wall probably need to go a bit over .030 to get there, so looking for a place to by a sleeve to take it back to standard.

Re: K301 vs K321

Wed Nov 20, 2013 9:38 pm

i JUST HAD MY 301 BORED OUT TO A 321. Thats an eighth of an inch isnt it? Isnt an eighth of an inch a hundred and twenty five thousandths.