QuestionQUESTION: I have had a Toro S-200 since it was new in 1978. About five years ago I overhauled it. The only real problem I found was that the hole between the decompression reed valves and the exhaust was completely plugged with carbon. While I was at it I replaced the rings. It ran better than new, blew snow like crazy -until last year when it developed a frequent miss. Still started on first pull, but lost most power when missing.
I just took it apart expecting a carb or decompression problem again. I cleaned the decompression reeds, they still appeared good and the passage was wide open. I removed a small amount of carbon from the exhaust in the cylinder port. I cleaned the carb meticulously, verified that ALL the passages were fully open using water and a syringe, all three idle holes were wide open as was the main jet. Rinsed out the carb with gas to remove water. The float valve seated tight. O Rings and gaskets were good. Spark plug is new and has a HOT spark. I cleaned the gas tank and filter, and replaced the fuel line. Gas flows easily to the carb and the primer bulb works normally. I preset both mixture screws at one turn, ALWAYS careful not to damage the seats.
Gassed it up with fresh gas and it started on the first pull. BUT when it warmed up enough to adjust the idle, it began to miss again, frequently and badly. I was able to blow wet snow OK, but not nearly as well as when it is not missing. ---When running I can turn the idle screw in until it seats and it still idles the same.--- Power screw has to be out over a turn before it has any power. It smokes slightly when it is missing, but clears up when not missing. At times it runs great, about ten percent of the time when idling, the rest of the time it misses, even stalls occasionally..
( I am sure I didn’t confuse the mixture screws, the idle screw, closest to the cylinder, has a knurled screw end and the needle end has a step in it. The power screw has a tapered end. Right?)
I will do an overhaul again this summer. For now I just want it to run decent enough to get through the SNOWY winter. Last overhaul I did was in minus 20 weather, no fun. I didn’t have a rebuild kit this time so I reused all the old gaskets, all appeared to be in great shape and I soaked them in oil before reassembly and socked everything down tight without warping anything.
Only thing I was unsure about is the adjustment of the coil spring and lever adjustment on the throttle which counters the vane. I have it set with slightly more tension than where it was. I am not sure if the throttle plate fully closes when idling. It was dark tonight when I finished reassembly.
Any ideas what to look for? How do you explain the apparent rich mixture? I maintain 12 small engines, they always work well when I do that much work on them. This one has me losing sleep. Any suggestions would be appreciated.
ANSWER: Hello Ed:
Send me the Model Numbers Off the Unit, Please. With these I can Locate the Proper Manual and Better Assist you. **If you Need Assistance in Locating the Model Numbers, then You can Go to this Site Addy; https://lookup3.toro.com/partdex/default.cfm and Select Step 1.** From your Description it Sounds like the Valve Clearances are too Close or the Carburetor is Not Completely Clean. If the Engine is Starting and Idling Good Until it Starts to Warm Up and then Starts to Miss, this is Usually a Good Indication that the Valve Clearances Require Setting. As the Engine Warms Up the Metal Expands. This Decreases the Space Between the Valve Stem and the Tappet. Some Toro Units Use a Kohler or Briggs Engine that Uses Hydraulic Lifters Instead of the Solid Tappets. If this is True for this Engine and it Uses Lifters instead of Tappets, then a Hydraulic Lifter May be Bad abd require Replacing. Thanks. Also, I have Never had Any Luck Cleanign Carburetors as you Described. I have Found that Soaking the Carburetor in Cleaning Solution Overnight is Best. Using a Breakdown of the Carburetor at the Site I Provided, Most People can Disassemble and Assemble the Carburetor (and other Engine Components) with Little to No Problems. The Cost of the Cleaning Solution I Use is $30.00us @ Gallon (I Use Gunk). The Gallon Can Comes with a Tray for Small Parts and the Carburetor Fits Nicely. Most Times a Carburetor can be Soaked and Cleaned and with the Float, Needle Valve and Other Carburetor Components being Soaked in the Cleaner with the Carburetor Body; there are No Parts to Replace on this Carburetor. If you Soak and Clean this Carburetor and the Float Needle Valve Still Does Not Stop the Gas Flow Properly, then Purchase a Needle and Seat Kit and Replace it. The Following is a Basic File I Made for Cleaning Carburetors. Any Input is Appreciated. Even though the Carburetor Looks Clean, the Internal Passages May be Restricted with Varnish that Gas Causes to Build Up over Time. Spray Cleaners Remove this Varnish in Layers, so Soaking is the Only Sure Way to Remove ALL this Varnish. I Suggest you Make Sure the Gas is Free Flowing to the Carburetor Inlet Port (if the Model does Not have a Fuel Pump). If the Gas is Free Flowing to the Inlet Port, then **Remove, Disassemble and Soak the Carburetor Overnight in Carburetor Cleaner (I Use Gunk). I have Found that Most People can Use a Breakdown/IPL and Disassemble the Carburetor Enough for Proper Cleaning. You Only have to Remove the Bowl (if Applicable), Float Pin (if Applicable), Float (if Applicable), Needle Valve and Needle Valve Seat if Applicable. This is a Flat O-Ring Located in the Inlet Port the Float Needle Rests in. Use a Strong Wire with a Slight Bend to Remove the Old Seat. Sometimes a Small Pocket Screw Driver can be Use Also. The New Seat will have a Slightly Beveled Side and a Flat Side. The Flat Side goes Towards the Carburetor Body when Inserted into the Inlet Port. Spray the Seat with Spray Lubricant to make Installation Easier. The End of a Drill Bit that is Slightly Small than the Seat can be Use as an Insertion Tool. Wear Gloves or Use a Rag when Handling the Sharpened End of the Drill Bit. Remove Any Adjustment Screws that Go Into the Carburetor Body. The Welch Plugs Do Not have to be Removed. If you are Able to Remove and Disassemble the Carburetor and Keep the Gaskets Intact, then Usually these Gaskets can be Reused. Even the O-Ring Around the Bowl can be Reused if it is Not Broken. The Only Parts you May Need to Replace is the Float Needle Valve (and Seat if Applicable). The Float Needle Usually is Not Replaced Unless it is Not Operating Properly (the gas flow not shutting off and the carburetor is Flooding). Do Not Remove the Main Nozzle. This is a Pressed Fit and Removal is Not Required for Cleaning. Soaking and Blowing the Carburetor Out After Soaking will Clean the Nozzle. Once Disassembled, then Soak the Carburetor Body and Parts in a 1 Gallon Can of Gunk Carburetor Cleaner Overnight. The Can has a Parts Tray Inside it for the Small Parts. Once the Carburetor and Parts are in the Cleaner, you can Replace the Lid for Safety and to Prevent Accidental Spillage. Then Blow Out the Passages with Compressed Air.*** (Do Not Use High Pressure Air for the Zama Carburetors, they have Check Valves for the Primer and these are Usually Blown Out of the Carburetor if Not Careful. Allow the Zama Carburetor to Set on a Drip Pan and Dry)***. ****All the Carburetor Adjustments are the Same for Lawn Mower and Trimmers. There are Several Location for the Air Mixture Screws. The Idle Air Mixture Screws are Usually Located at the Top of the Carburetor Bowl and the Top of the Carburetor Body. If the Main Air and Idle Air Mixture Screws are Side by Side on the Side of the Carburetor, then the Idle Air is Nearest the Engine. The Main Jet Air Mixture Screw is Located in the Bottom of the Carburetor Bowl or Beside the Idle Air Screw on the Side of the Carburetor Body. Some of the Older Model Carburetors have the Main Jet Mixture Screw Straight in from the Top of the Carburetor Body (this is Rare anymore). If you have Cleaned the Carburetor (Disassembled and Soaked Overnight in Carburetor Cleaner (I Use Gunk). Then Blow Out the Passages with Compressed Air and Install a New Kit if Required. Now Setting the Air Mixture Screws: ****Turn the Idle Air and Main Air Mixture Screws In Until SNUG **Do Not Jam** Then Reverse Both Screws 1 1/2 Turns. Holding the Throttle Full Open, Start the Engine. Turn the Main Air Mixture Screw Clockwise Until Proper Revs are Obtained. Occasionally you May have to Turn this Counter Clockwise to Achieve the Proper Revs. Now Allow the Engine to Idle. Set the Engine Idle Screw (Not Idle Air) so the Engine will Stay Running if Required. Now Set the Idle Air Mixture Screw so there is No Hesitation when Throttling from Idle to Full Throttle. Reset the Engine Idle if Required.**** If This Carburetor has a Single Air Adjustment (Except Tank Mounted 9200 Model Carburetors), Use the Section Above that Pertains to Full Throttle RPM Air Mixture Screw and then Adjust the Screw if Required to Eliminate Any Hesitation when Throttling from Idle to Full Throttle. For the 9200 Model Tank Mounted Carburetor Adjust the Air Mixture Screw Full In, then Reverse 1 1/2 Turns. Set the Throttle Lever to Full Throttle and Start the Engine. Now Carefully Use 1 Finger and Open the Throttle Plate and Over Rev the Engine Slightly. If the Engine Over Revs and Does Not Struggle to Over Rev, then the Carburetor is Set. If the Engine Struggles to Over Rev, then Turn the Adjustment Screw In 1/4 Turn and Repeat the Over Rev Test. If you Adjust to 1/2 Turns In and the Engine Still Struggles to Over Rev, then Return the Adjustment Screw to 1 1/2 Turns Out from Snug and Turn the Screw Out 1/4 Turn. Do the Over Rev Test. Continue this Process Until you have the Engine Over Revving without Struggle. By Adjusting the Carburetor on this Style Carburetor Until the Engine Over Revs without Struggle, you have Adjusted the Air Mixture to the Best Possible Setting. This file was Intended to Give you the Basic Carburetor Cleaning Instructions and May Not Reflect Your Carburetor Components. If you have Questions, Please Ask.
Respectfully
John
PS: I am Allowed to Answer 10 Questions a Day. If you See I am Maxxed Out, then Try Submitting your Question at or Just After 8pm EST (US). My New Day Starts then. Comments and Ratings are Greatly Appreciated. Thanks.
Respectfully
John
---------- FOLLOW-UP ----------
QUESTION: Thanks John, Here is the additional info.
Model Number of Toro S-200 (1978) is 38120-9000001 & up Engine is 2-cycle Tecumseh.
I tested the ignition and new spark plug with one of those cheap testers with two colored neon lights. The results indicated that the plug, plug wire, magneto and coil were all good.
I have had an almost identical problem on two different McCulloch chain saws. Replacing the carburetor on the first one cured it, but a new carb on the second saw had no effect.. The engine misses and sputters just as the Toro snowblower does and the mixture screws have little effect. I have worked on my own small engines for almost fifty years, never ran into this problem before. I use fresh gas. I always use StaBil in the last tank of gas, run the engines to circulate the StaBil, drain the tank and run the engines until they stall with the choke on. I ran the Toro snowblower for 25 years before I opened the carb. for the first time. I have never encountered a small engine with good compression which I could not get to run well before, now I have two! Have you encountered any possibilities other than the carb?
Thanks again, Ed
AnswerHello Again Ed:
Thanks for the Earlier Comments and Ratings. I have a Few Questions. Have you Replaced the Point Set and Condenser? Is the Base Cover Plate Tight and the Cover Plate Gasket Good? Is the Shroud Base Tight and the Shroud Gasket Good? Thanks:
Respectfully
John
PS: I am Allowed to Answer 10 Questions a Day. If you See I am Maxxed Out, then Try Submitting your Question at or Just After 8pm EST (US). My New Day Starts then. Comments and Ratings are Greatly Appreciated. Thanks.
Respectfully
John
