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Engine machining and material question

I currently have a Kohler twin cylinder air cooled engine torn down on the bench. It's not well supported by the factory, overpriced parts ect. I'd like to put valve seat inserts in it. It's a cast iron jug.. Thinking bore the hole using a mill and then turn the insert to fit. Turn insert .003 under size, press fit. Any thoughts on expedient material for insert, this is non critical lawn & garden application. Anything else I'm missing here?

Also the jugs have worn a taper at the upper end, normal repair is bore oversize, use new piston. No way am I paying $116 each for new pistons on this beast. Old pistons are serviceable, looks like a dry sleeve would bring it back to standard. The lower part of the bore is not excessivly worn. Federal Mogul has a 9" sleeve that would do the trick. Do I bore .003 over the sleeve size,? Can just the tapered part be sleeved and rebored/honed to spec? Any words of wisdom appreciated.

DE

Reply to
DE
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"Also the jugs have worn a taper at the upper end, normal repair is bore oversize, use new piston. No way am I paying $116 each for new pistons on this beast."

The old way is bore out most of that taper and knurl the pistons, isn't it, to reestablish the fit?

I've never done this... I gas-ported a small engine piston once. You can buy oversized rings cheaply and grind the gap with a gap grinder to make them fit the new bore.

It has something to do with piston slap, I think.

--Doug

Reply to
DGoncz

No way am I paying $116 each for new

wow you can get new ones made for less. thats a real rip off.

Reply to
Erik Litchy

I've rebored small outboard motor engines by mounting the block on a face plate, indicate for runout, and then bore with a boring tool. Then hone with a homemade emery cloth flapper mounted on a stick chucked in a power drill.

I've done a 4HP Evinrude two cylinder block on a Southbend 10L.

Tony

Reply to
Tony

What model engine is it. If it is a old model then there's a good chance that aftermarket parts are available. I can look them up with the model number.

As to the valve seats check the size of the valve OD and seat ID. I might have some seats that will work.

Seats should be made from the hardest steel possible for long life but softer steel will work for a while.

Wayne Cook Shamrock, TX

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Reply to
Wayne Cook

That's pretty normal for OEM small engine parts. It's ridiculous but there's not much that can be done in some cases.

Wayne Cook Shamrock, TX

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Reply to
Wayne Cook

It's a KT17QS, there were aftermarket parts until a year ago, now the only thing available is rings in std. I've had this since '81 and it's been a decent unit. I've been scrounging parts for the last year off ebay. I've got a good extra sets of jugs w/pistons but they're both for the left side. The only difference between the left and right is the hardened seat in the exhaust valve. I figure to put a seat in the intake side and use it on the right side. It'll work fine. The lower end is tight ,it just has excess blowby.

The other option is dry sleeve the old jugs, the taper is at the usual area where it makes compression.

Seat ID measures 1.240 valve face 1.380 i've done this on auto application years ago with a neway setup. I suppose it could be farmed out but since I have this milling machine........

I guess I could just use the cast seat and do valve job but I think I would be sorry.

Reply to
DE

Reply to
Eric R Snow

Ok. I finally got a chance to check. That's not one of the old cast iron engines so parts aren't as available. One company did show a aftermarket standard sized piston assembly but it was expensive as well.

Possible but a lot of work.

Ok. Unfortunately the seats I've got are to small. They're 1.125 ID and 1.340 OD. I had hoped that they would work since I've got a bunch of this size.

It would work just not as long as a good hard seat.

Wayne Cook Shamrock, TX

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Reply to
Wayne Cook

On Fri, 11 Feb 2005 11:34:25 -0600, Wayne Cook wrote: .

I appreciate the search, the long block is back together with the salvaged parts. Left the exhaust valve on the cast seat, time will tell on how it lasts.

DE

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Reply to
DE

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