Honda 200m Exhaust valve seal

[BarnBoy]

My 200m is burning some oil when it starts up. It goes away after a few minutes though, so I think that the valve seals need to be replaced. I am pretty sure it can be done without removing the head. How do I go about doing it? How long would it take; how much work is involved in doing this?

[barnett468]

More than likely the rings are worn also . . as far as I know, the head needs to be removed to replace the seals st which point you might as well check the valves to see if they are leaking and check the guides to see if they are worn and check the csm and rockers to see if they are excessively worn.
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[YTZ drew]

I don't know of any way to change them with the head still on. You would need to take the top cover off the head, which requires removing the 4 acorn nuts that hold the head to the jug, so air pressure could not be used to hold the valves in place like you do when changing valve springs and seals on car engines. Heads got to come off, but that's not a bad job. It takes longer to pull the engine out than to pull the head and put it back on. You may even be able to get the head off in the frame, not sure if there's enough room on that model.

[BarnBoy]

Well, to the best of my knowledge the top end has been rebuilt. That was probably 10-15 years ago though, but it has not gotten very much use since then because it was sitting in a barn for 10 years. They fixed it all up and then it just sat there. I think the seal may have gotten hard or dried up. I thought it would be possible to change using air to hold the valve in, but I guess not. Is this a very time consuming job, or could it be done in a day or so? Thanks.

[BarnBoy]

Also, when I first started using it after I got it, it would only smoke for a minute at the most and then stop. Now it smokes for 3-4 minutes. It used to only smoke when I first started it up in the morning, and the only a little bit again if it had been sitting for an hour or 2. Now it smokes more when it starts up and if it has been sitting for 5-10 minutes, it still smokes a lot. The engine is still warm though if it has been sitting for only 5 minutes, so that is why I figured it was the valve seal that needed to be replaced.

[YTZ drew]

It does sound like the seals. Sometimes when people "rebuild" these engines all they do is toss in a new piston and rings like you would on a 2-stroke. Often the valves and seals get ignored due to lack of experience with servicing them, or lack of the appropriate tools. The head is easy to remove and tear down, I just did one a week ago, and its still on my bench waiting for a new rocker arm. If you have to pull the engine out, that will take about an hour, but the whole job is definitely doable in a day.

[BarnBoy]

Ok, thanks a lot. Hopefully the engine does not need to be taken out though, but I will have to see. I don't need any special tools, do I? It also leaks oil from the CDI. I am assuming that it is leaking from the seal around the shaft (not sure what it is called; cam shaft?).

[barnett468]

No you do not need special tools other than a torque wrench

The top end can be removed with the engine in the frame.

Yes its called a camshaft and there is a seal that is replaceable.

If you want to remove the valve spring yourself you need a small valve spring compressor.

After removing the head, put carb cleaner in the ports then lift the head straight up and look around the valves for moisture/leaks . . if there are any it should be repaired.

A shop will need to check the valve clearance and measure the cylinder for taper and out of round . . the piston should also be measured.

Post photos of anything you want . . photos of the piston might be helpful.

[ps2fixer]

Sounds like you will need #2, #10, and #11 in the diagram below.

http://www.partzilla.com/parts/searc...TOR/parts.html

If you have a top end or complete engine gasket kit, it should have the o-rings and gasket, #10 might not be in the kid though. #6 isn't a bad idea to change too, but it is more or less a dust seal.

[BarnBoy]

Ok, thanks for the advice. I don't plan on digging into it that far. I just want to fix the leaking and smoking.