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Okay.. First Off I have rebuilt a lot of small engines over the last 20 years and I have never had a problem like this. did a complete rebuild on a 1985 wheel horse with a K17 engine 17hp. the problem is it pops sometimes at idle through carb, doesn't have power under load compression is low on number 1 cylinder excess fuel build up. Now I can't see how it could have gotten out of time.. but wouldn't both cylinders act up if it was out of Time? the valves were done at the machine shop. I have heard that a baffle in the muffler can block 1 side I don't think that to be the problem. I guess I question the timing or a valve but I think that I maybe over thinking it, so Id like to pick someone's else head and see what they think, oh fly wheel key seemed fine too. have not run engine much because of problem. any thoughts??? also the number 2 cylinder warms up like normal and the number 1 stays cooler.

I would start by finding the compression of both cylinders. If there is more than a 10 percent difference then I would follow that with a leak down test to find where the compression is being lost. You could have a exhaust restriction, but that wouldn't effect compression. Most likely a valve isn't sealing or maybe a broken ring, or faulty head gasket.

The very first thing I would do is a leak down test or compression test. Sound like a tight valve to me, have you checked the valve clearances. Isn't that the engine that has only one coil for both cylinders which fire at the same time ? So I don't see how it can be timing unless you have a bad coil. You did check the coil didn't you?

I agree, check the valve clearances first, even pull the head on the low compression side and look. Look closely at that intake valve.

Thanks for the reply's. Yes there is big compression difference # 1 is very little compression. and Yes reynoldston that is the engine that has one coil and from what I can tell is okay. Also if it was a bad coil it shouldn't affect the compression I wouldn't think. From my test the head gasket seems okay. Yes I have pulled the head I think I question the exhaust side more than intake. The valves were done at the machine shop and set I didn't see in my manual where it gave me the valve clearances. I thought it said non adjustable. I will re check. It has the original valves in it they were re ground. New guides. I keep thinking Valve issue too. they say if the timing gets 1 tooth off it will cause the 1 valve not to close tight, but again if its on 1 cylinder I would think it has to be off on the other. I will check deeper into the valves on that cylinder as soon as I have time.

It sounds to me like whoever did your valves didn't adjust them proper. Intake .003 to .006 Exhaust .011 to .014 They are adjusted by grinding the end of the stems. If they grind the seats and valves they must also grind the stems. Their valve grinder has a attachment on it for this but I have done it in my shop with a power sander but be very careful if you do it because you can grind them too much without trying.

Fish said:

I agree, check the valve clearances first, even pull the head on the low compression side and look. Look closely at that intake valve.

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Yeah, just check the valves first.

reynoldston said:

It sounds to me like whoever did your valves didn't adjust them proper. Intake .003 to .006 Exhaust .011 to .014 They are adjusted by grinding the end of the stems. If they grind the seats and valves they must also grind the stems. Their valve grinder has a attachment on it for this but I have done it in my shop with a power sander but be very careful if you do it because you can grind them too much without trying.

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Thanks again I will be checking into the valves This week. I did take a quick peak and it looks like there is no clearance in them. I have to wonder if the number 2 cylinder Valves are right too seeing this. I have never had the machine shop get them wrong before. as soon as I get time I will check them further .

Vintage Mowers said:

Thanks again I will be checking into the valves This week. I did take a quick peak and it looks like there is no clearance in them. I have to wonder if the number 2 cylinder Valves are right too seeing this. I have never had the machine shop get them wrong before. as soon as I get time I will check them further .

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We live a long ways apart and I don't know anything about the machine shop you used. I am just making a guess here. The reason I mention the coil is I had one in my shop this pass summer that ran like you described your ran and that had a bad coil but also that mower wouldn't run at all when it got warm. How did your mower run before you took it apart?

reynoldston said:

We live a long ways apart and I don't know anything about the machine shop you used. I am just making a guess here. The reason I mention the coil is I had one in my shop this pass summer that ran like you described your ran and that had a bad coil but also that mower wouldn't run at all when it got warm. How did your mower run before you took it apart?

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It ran and did have power but it was getting worse it was burning Oil as fast as you could put it in.. it didn't pop at an idle like now. It did start really hard when hot, but we assumed the condition of the engine was the cause of that. I have not ran it that long because of the problem now. I would assume if the coil was bad I would still have compression too. as far as machine shops there are very few around here anymore. I have only used this one 4 or 5 times but never had trouble with valves. the ones I used to use are gone. In fact there really are not any other ones around here now. there doesn't seem to be any clearance.. on either the intake or exhaust which would not be right.. I assume that I should get the clearance right first and see what happens. Not sure if we will try that ourselves or try the machine shop like I said my choices are very slim around here.

Go to TDC on each cylinder and check with a feeler gage. I sent the specs earlier. If they are tight you will have to remove heads and valves. When very carefully grind the valve stem ends till you get the proper clearance. I say be careful because its very easy to grind too much.

Thanks again ,and yes I did check them at TDC and I could not get a feeler gauge in there, I got the spec but I couldn't even get a lesser feeler gauge in them. Yeah I will have to carefully grind. I will wait till I got a little more time so I don't get in a hurry.

Vintage Mowers said:

Thanks again ,and yes I did check them at TDC and I could not get a feeler gauge in there, I got the spec but I couldn't even get a lesser feeler gauge in them. Yeah I will have to carefully grind. I will wait till I got a little more time so I don't get in a hurry.

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Grind them to the low number because you can soon grind too much. Been there and done that. You can get by a little on the loose side if you do grind too much.

reynoldston said:

Grind them to the low number because you can soon grind too much. Been there and done that. You can get by a little on the loose side if you do grind too much.

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Sounds Good and I was thinking the same thing when I get to low number just stop don't push it Thanks Again...

If there is a big difference in compression between the two cylinders, definitely look at the valves first. The Kohler KT 17, 19, and 21 engines used a valve rotator on the exhaust valve springs and if they stick, they may not allow the exhaust valve to close completely. A leak down test is your best option with out tearing everything apart. Another thing that hasn't been mentioned here is that the KT engines and all Kohler engines with a battery ignition system for that matter, need to have the ignition timed using a timing light. The ignition timing won't have anything to do with compression in the cylinders so you must address that issue first. One more thing that can cause a cylinder not to fire is the spark plug lead from the coil to the spark plug that is burned or broken inside the insulation. Just relaying some of my experiences with the Kohler twin cylinders back in the day!

cashman said:

If there is a big difference in compression between the two cylinders, definitely look at the valves first. The Kohler KT 17, 19, and 21 engines used a valve rotator on the exhaust valve springs and if they stick, they may not allow the exhaust valve to close completely. A leak down test is your best option with out tearing everything apart. Another thing that hasn't been mentioned here is that the KT engines and all Kohler engines with a battery ignition system for that matter, need to have the ignition timed using a timing light. The ignition timing won't have anything to do with compression in the cylinders so you must address that issue first. One more thing that can cause a cylinder not to fire is the spark plug lead from the coil to the spark plug that is burned or broken inside the insulation. Just relaying some of my experiences with the Kohler twin cylinders back in the day!

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I did try a different plug wire and yes we did try to time it with light but the way it was running may have to do it again.. But appeared right. The valves on the # 1 cylinder seem to have no Clearance at all... what is this rotator you spoke of? Regardless of that there should be the right clearance in the valves correct. # 2 Cylinder intake is in spec and exhaust is a little tight. Thanks for the input...

reynoldston said:

Grind them to the low number because you can soon grind too much. Been there and done that. You can get by a little on the loose side if you do grind too much.

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UPDATE!!! I ground them the best I could with what I had to work with and kept them at the minimal on number 1 and I touched up the exhaust on # 2 intake was in spec on 2... Seems to be running great now... it appeared they did the number 2 cylinder but not the number 1... anyways so far its running great... Thanks Again... never had that happen before with a machine shop.