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Good morning!
My snow king has a HMSK 80 engine on it and it was running rough. It was not a smooth idle. The plug was getting black pretty quick. I bought it that way thinking I would just buy a new carburator, and the price was a real deal. New carb. and same thing. I'm now at the point it will only run on the primed gas. I started taking it apart to check valves and other things and this is the first "problem" I saw:
Is this a good indication of running poorly? I took my wire wheel to it and cleaned it up.
After I took the head off, my unexperienced eye thought the valves and piston look to be hardly used.
Any opinions and direction appreciated.
R&R

The new carb you installed should have a part number of #632334A. The valves and piston head look great, but did you check to see if the valves are closing tightly? Set the piston 1/4" down past TDC and check to see if you can twist either of the valves, they should be very tight. If they are, after reassembly with new gaskets here are a few things to check and some questions to help us help you. Also, set the armature air gap at .010.

1. Can you post the spec number?
2. Check too see that all gaskets are tight and not leaking.
3. Check too see if the tank, filter and lines are allowing fuel to flow freely.
4. Is your rough running surging (RPM's going up and down) or popping and missing.
5. Does it run rough at idle only?
6. Does it run rough at high speed only?
7. Does it run differently if you open or close the chock?
8. Your carb has idle and high speed adjustments. Have you tried changing either or both of them?

Remember, we are not standing beside you. You are our eyes, ears and fingers, please give us the best description you can, so we can help you out.

Here is a manual which may help you out.

http://www.mymowerparts.com/pdf/Tec...P-4-CYCLE-L-HEAD-FLAT-HEAD-ENGINES-692509.pdf

Rivets, you've already helped me out! Great questions.
I'm heading out for the evening, but will respond to questions 1-8 shortly . You didn't mention the nasty rust on the armature. If I had done everything "right" would the very rusty flywheel metal cause any possible problem? I'm not trying to sound like I'm taking a shortcut. I'm trying to add to my "man cave" education.
Thanks for responding.
And it's yard king, not snow king:ashamed:
By the way that manual is outstanding! I printed it from a different post yesterday.

In my opinion the rust is a non issue. I didn't bring it up as not many on this forum agree with me on that point. That's why I just pointed out to set the air gap properly.

Is this the spec number? sorry it's blurry, it's the best of the three I took!
View attachment 25163
The carb I bought came from China. It has the same number you gave me. I'm not a price shopper, but I figured even if I bought from a US supplier it's probably the same thing? Please correct me if I'm wrong.

Valves are very tight at 1/4 down from TDC. I tried seeing light through the valve's and don't see anything FWIW. I'm going to take the valves out this weekend and lap them per a video I saw on you tube of a guy redoing his HMSK 80. I've never done this on an engine, and I'm going to try it. Looks pretty straight forward...?
Haven't checked all the gaskets. Intake, exhaust, and head looked good...
3. Gas running freely. Even took the gas cap off in case it was venting issue.
4. engine was popping and missing when it was running. If I increased the idle, (which I thought was too high) it hardly missed.
5. I don't remember if I got a good idle or not. I did adjust the main first at high speed, and then the idle circuit.
6. answered in 4&5
7. choke would "drown" it out.

I will pay closer attention after it's back together and report back. The snow in Illinois should just about be done for the year by the time I'm finished..

Please type in the spec number, attachment would not open. When reassembling, please use a new head gasket. I'll watch for your post after reassembly.

Hopefully this time it will work.
Thanks for the help Rivets. I have a few new gaskets coming in the mail.

Happy weekend to all!
To those following this thread, I'm happy to report that my snow blower is now running. It's not running as well as I would like it too, but if N.Illinois gets 6 inches of snow tomorrow I think it will do the job and save my back.:thumbsup:
Here's what I've done, and how it's running:
I took the head off and lapped the valves. They didn't look bad to me, but this is my first experience in doing it. I looked for burn marks, pits, anything abnormal in the "seat" or valve. I do have one question though for the pro's, The intake valve keeper has a right and wrong way to install it. I tried finding a picture on line of the correct way. One side has more rubber, or seal to it and that side went up. I figured the spring should push against all metal instead of the rubber seal. I hope thats not too confusing. I didn't realize there would be a difference.
I cleaned up one rusty magnet on the flywheel and reset the gap. .010 is very small, and it was hard to get it exact. It seemed as the magnets passed the pickup coil I got different measurements. I used the method I saw on line of folding a index card in half, centering the magnets on the coil and retighten. I checked the gap again after that.
Here's how it runs now on carb 3: Prime and full choke it started first pull. Major improvement.
I let it warm up and tried to adjust the main jet in the carb. Middle point between unscrewing jet and rescrewing jet as engine stumbles. I didn't think the rpm was very high so I increased the idle speed screw to a higher fairly steady idle with only an occasional "pop" from the exhaust. I then tried getting a low idle by adjust the rabbit to turtle lever, lowing the lever until it came to the indent. No change in rpm at all. when I adjusted the low speed jet the engine slowed down, but when I pushed to full throttle there was no change. I then adjusted the full throttle to a good running speed and let it run for a little bit and shut it down. Only a minor backfire.
I just pulled the spark plug to see how it looked, and it's wet, looking like it's running rich still.
2 more things. Gas cap is new, and spark plug is new.
Any suggestions greatly appreciated.

Ok, the first thing I would suggest is to reset the armature air gap with the single thickness of a business card, unless you are sure you have a gap of .010 inches. I don't normally recommend doing it this way, but in your case it may be best. Second, this is the procedure I always taught my students to adjust a carb with two fuel controlling needles.
1. Start the engine and move the throttle control to top speed.
2. Adjust the high speed needle (this is the one under the float bowl) clockwise very slowly until the engine starts
to bog down.
3. Back the needle out 1/8 turn, the engine should now run smoothly.
4. Now move the throttle control down to idle. If the engine stalls out turn the idle speed screw in one full turn,
restart the engine and bring the throttle control down to idle. If the engine is running to fast, turn the speed
screw slowly out until the engine seem to want to die and then in 1/8 turn.
5. Now with the engine running, adjust the idle needle out until the either gains in RPM's or starts to bog down. If
the engine gains in RPM's, continue to adjust out until the engine starts to bog down. At this time turn the
screw in 1/4 turn. Now the engine may be running to fast, so turn the idle speed screw out until you get an
RPM you like.
6. Now you must repeat step 5. If the engine bogs down right away turn idle needle back in to your starting point
and go to step 7. If it speeds up, repeat step 5 again.
7. Turn idle needle in until the engine bogs down and then out 1/8 turn.
8. Now the engine should run smoothly at all speeds.
9. To check, set the engine to idle, then quickly push the throttle control tohigh speed. If it dogs and does not
come to speed, open the idle needle 1/8 turn and repeat.
10. Set to go.

There are 2 reasons I have it done this way is, first the high speed needle controls the fuel going to the low speed circuit and second is that the idle needle controls how much fuel is used when going from idle to high speed. You should also review the section in the manual I posted before starting this procedure.

since I don't like wondering what the final results are, I continue.
I took the cover off the motor and re-set the magneto. I took it off first and cleaned the contact surfaces just for the fun of it.
I started the snow blower up and let it warm up. Started good. After going back and forth with adjusting the needles I had what I felt was a pretty smooth running snow blower.
After about 20 minutes I headed for the shed to put it away and out of my garage. As I was going into the shed (it's up about 6 inches) the motor died! I thought maybe it was out of gas, but I have clear fuel lines so I could see that it wasn't, although the fuel line wasn't solid gas. I pushed the bowl drain and I wasn't getting any gas coming out of it. I came back about 30 minutes later and pushed on the drain again and the gas came out. When it first died, I pulled the hose off the shut off valve and it didn't seem like it was a very good stream, but I thought plenty to run a 8 hp motor?
After doing a few searches, I'm going to take the tank off and clean it out. (It looked clean when I had it off to do the valves). Maybe change the shutoff... Glad I have a few months to figure out what's wrong..

Before pulling the tank try this. Run the unit until it stops. Immediately remove the fuel line from the carb and check fuel flow. If the fuel flows freely, the float needle is sticking. If the fuel flow is slow, then look at the tank for blockage. Is your fuel shut off mounted in the bottom of the tank or inline?

Originally when it quit I did pull the gas line on the "carb" side of my in-line shut off valve. It was flowing, but not like what I would expect. That's why I was thinking it was something with the tank. Thanks for the help so far.
R&R