QuestionI have a B&S Model 31M777 Type 0234E1 Code 030206ZE that started backfiring through the carburetor. It had a slight oil leak around the OHV cover so I started there cleaning and I took off the cover to seal it with some “form - a - gasket.” When I looked inside I saw that the exhaust valve rocker arm was extremely loose. I found the valve stem cap/shim lying in the bottom and the adjustment nut was loose. It didn’t look like the push rod was bent so I put it back together. I cycled the engine through a few times to set the rocker arm to about what the Intake valve was set for. Changed the oil, gas, & filters and it runs OK at full speed but doesn’t idle very well it wants to sputter a little and misses every few seconds. I must say it’s run in a pretty dusty environment at times so I’m wondering about tune-up procedures and other tips.
1. Can you tell me what I should set the valve clearances for (and any tips or suggestions)?
2. Do you have any info/procedures for cleaning the carburetor or any other suggestions?
I think this is a great service by the way.
Thanks in advance,
Jeff
AnswerJeff
I have been pondering this question and here is some help for you.
The Spring Checkout
Assuming you have fresh or treated fuel installed in your engine, what other things are important that the homeowner can check before the Spring startup? Let's make a short list of things I consider important.
Thoroughly clean the unit. If possible learn how to remove the blower shroud, so that you can clean debris from the cooling fins. This is very important because the only way the engine can run at the proper temperature is if it can get good air circulation. Make a habit of checking on this during the season. You can either clean it with air or wash it with the garden hose. If you use water avoid getting it in the fuel tank. Engines with ignition points should not be washed until tune up time.
Remove the spark plug and examine it. A lot can be told from looking at the spark plug. A normal plug electrode should be dry and slightly tan colored. A wet oily plug could indicate internal problems causing excessive oil consumption.
After you have the engine clean, remove the air filter and replace it with an original equipment filter. Cheap imitations just aren't worth the risk of ruining an engine. If the filter is a foam type be sure to follow recommendations on oiling it. Be careful not to let dirt fall in the clean area of the carburetor air inlet. A faulty or improperly serviced air filter can ruin an engine in a matter of minutes. Once the dirt gets into an engine it forms a grinding compound in the ring and crankshaft area.
Change the oil, again being careful not to let any dirt enter the engine. Use the engine manufactures recommended viscosity for your expected temperature range. I usually use either 10w30 or 30w. Check the oil often during the season and change it when it looks dirty.
Check everything over for any loose bolts, dull blades or recommended maintenance in your equipment owners manual, including proper operation of all the control and throttle cables. A little WD40 can be helpful here.
For the most part good maintenance practices involve common sense and a picky eye to eliminate any potential problems during the season. If you find a problem that you are not sure about, check with a local small engine dealer. Most have been trained to spot and handle these problems. Sometimes what looks like a big problem is really not and can be resolved early before any major damage occurs. Proper governor operation is very important and if you suspect the engine is over speeding, get it checked immediately. Once again, CLEAN OIL and CLEAN AIR are the two most important things to an air cooled engines life
Now for the valves
You don't adjust OHV engines at TDC. You must bypass the compression release by turning passed TDC and letting the piston drop 1/4". Using a plastic ball point pen as a tool in your spark plug hole you can let the piston push the ball point pen out of the spark plug hole till it starts returning inside the cylinder. Make a mark on the pen so you can see the 1/4" drop of the pen. Then set your valves at 0.004 clearance for both IN/EX. Note: This is a general valve clearance specification that covers most engines today. Check your maintenance book or ask your local dealer for the info on the valve clearance for your specific engine
