Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: version B 2.10.1 6/24/83; site hjuxa.UUCP Path: utzoo!watmath!clyde!burl!ulysses!mhuxl!houxm!houxz!hjuxa!gmp From: gmp@hjuxa.UUCP (PLEWA) Newsgroups: net.auto Subject: Re: Help with a lawnmower engine Message-ID: <142@hjuxa.UUCP> Date: Tue, 5-Jun-84 21:04:04 EDT Article-I.D.: hjuxa.142 Posted: Tue Jun 5 21:04:04 1984 Date-Received: Wed, 6-Jun-84 07:24:04 EDT References: <2091@ihnss.UUCP> Organization: Digital Equipment Corp., Holmdel, NJ Lines: 33 The problem you appear to be having is a generic problem with old "El Cheepo" Briggs & Stratton engines. There is either a large amount of carbon buildup around the intake valve, which tends to restrict the flow of carburated air from entering the cylinder. This in its extreme, will even prevent the valve from closing completely. The other cause way be just excessive wear of the aluminum cylinder wall. The determination of which is relatively simple. First remove the spark plug and squirt a small amount of 30w motor oil into the cylinder. Reinstall the spark plug (don't connect the plug wire) and pull the starter cord. If the compression (effort to pull the starter) has increased, than the problem is excessive cylinder/piston ring wear. If the compression remains the same then the problem is due to poor valve sealing. (The oil only tends to increase ring to cylinder seal) Excessive ring wear on this engine is cost in-effective to repair. Valve seal or restriction on the other hand can be repaired with out too much cost if you are willing to spend some time. The process consists of removing the head and valve tappet cover. Removing the valves and scrapping off all carbon build-up. The valve seats can be restored by "lapping" with lapping compound, which is an abrasive powder in an oily paste. The paste is applied to the seatting surface of the valve, and the valve is inserted into the port from which is was removed. The valve is then rotated back and forth 1/4 turn. This causes the mating surfaces to be polished to a positive fit or seal. When this has been done to both valves ALL traces of lapping compound should be cleaned from both the valves and the block. Alot of damage will occur to the remainder of the engine if this is not done. Reinstall the valves, reinstall the head and tappet cover, and your problem should be solved.