James S - I hope alot of the guys respond to your question about whether to use genuine Kohler parts or aftermarket parts in your K321 rebuild. One thing for certain is that the genuine parts have a proven history while aftermarket parts may still be proving themselves. I think for the most part you can still find genuine Kohler K321 parts although it might take some searching since I don't think Kohler is producing most if any of them anymore, but not completely sure. However, there are many dealers out there with alot of NOS parts. I've never done a complete rebuild on my own. I've always had a pro do it or assisted someone I consider a pro. My comments are based on this experience, what I've been told by these pros, and what I've seen when assisting them in doing it. When it comes to the rings, piston and connecting rod, I certainly lean towards Kohler, and even for the head gasket. I don't think the price difference between Kohler and aftermarket for just these parts is more than $100, which is probably worth the peace of mind knowning they should be good for 10-20 years of use. The pros will likely want to stick with Kohler for these parts as well unless they can see the aftermarket part and have some sense that it at least looks good and will work. It's a touchy feely thing - if it looks good and feels good it probably has a better chance of actually working good. May sound strange but I've seem some aftemarket rings and got strange looks and comments doubting if they really work. Going on to other items, if you're looking for a new crankshaft I don't know if they are available aftermarket except from someplace that does them special for puller engine use and they are pricey. I have heard/seen NOS cranks around that could be had for not to great a price. In my view when it comes to a crank I have to think they could be found in used condition, and machined to re-useable spec's, which is the only thing I've ever done. As for main bearings, I've heard 2 stories - that they are always pitted and need replacing, and the exact opposite, that most guys almost always reuse them. They are so substantial they almost never fail anyway so I lean to the latter for my use. And when it comes to the other things like gaskets and seals, well, aftermarket will likely work ok. I don't have a specific preference just a matter of whether they are actually good quality. I've not really had that many engines completely overhauled and I never kept and used any long enough to have developed a known history. About the best I can say is that for the few I've had completely rebuilt I never heard of the next owner having a problem. My Kohler 341A sitting in my 169 in the garage has a Kohler .003 oversized piston, Kohler .010 over-sized rod, original crank ground .010 under, original main bearings, and the remainder of the gaskets, etc all original Kohler items. It doesn't have more than about 10hours run time in 10 years so it's not really a good example except to say it's all original parts. There certainly has to be some guys on here that can speak from their actually experiences using long hour rebuilt engines, so lets see what they have to say. My son is getting close to having a couple engines rebuilt so I'd like to hear the latest recommendations myself. With regard to the sponsors, I think at least most can provide genuine Kohler parts, and at least 1 or maybe 2 is a Stens dealer as well, and has that aftermarket brand available. In my view it's always worth speaking directly with them to get some history of their experience using these parts in their shop if they have one, and their customer feedback if they do and don't have a shop. I don't know of any particular brand or part that has a reputation for being a problem. I have heard alot of the aftermarket head gaskets are not up to the quality of Kohler, and they use cheap materials that don't hold up resulting in what should be called premature failure. Things like the gasket itself coming apart, the holes not located quite where the bolts fit, basically poor quality issues, so this is the one specific item I have used many times and do stick with Kohler. I haven't purchased one for sometime but Kohler used to package what was called a "Renew the Power Kit". It had the points, points push rod, points cover gasket, valve cover gaskets and breather filter, and the all important head gasket. Basically a major tuneup kit so you would use when de-carboning the head and piston, replacing the points, and adjusting the valves. I discovered the price for this kit was about $5 more than the price of just the points with a push rod - almost a no brainer. It's kind of hard to find a dealer that carried it but if you can't and want one shoot me an e-mail and I'll see what I find in my records. Hope this helps and the other guys post their experience and recommendations.
Hydro Harry
Old Cubs Never Die (and having their Kohlers reworked helps)
