Small Engine Help

pacodiablo · July 21, 2003

As some know I have an old McCulloch 2 stroke engine. It is a miracle the magneto even pulls (this engine sat for 10 years - nobody even pulled the chord), but I got it running...sort of. I originally used silicone to seal the carb, but the gas ate away at it because I used the wrong kind (it was just laying around). After that I ordered a rebuild kit. I installed the kit, but lost one screw that holds part of the carb together. I found a similar screw that had a different head and thread pattern. I filled the tank with 20:1 and pulled the chord. Nothing happened. I repeated until it did, and it ran good, but it would die within seconds of being cranked. Could the incorrect screw cause this? I think it is a possibility...maybe it did not hold tight enough allowing gas to leak through the gasket? I used starting fluid, which helped a little. Could the gas have been bad? The gas has sat for some time, but no more than 5 or 6 months. The magneto pulls fine, I have had the throttle and choke on. What could be the culprit of this engine's failure?

MCourson · July 21, 2003

Sounds to me like it could be an oil fouled plug. I have always used 32:1 and it still fouls em.

pacodiablo · July 21, 2003

Nope. The plug is new and as clean as can be, I checked it out.

MCourson · July 21, 2003

Ok well there isnt too much that can go wrong since small engines are fairly simple. First we already know it is has spark so that part should be ok. Second I would check whould be the carb. Gotta have fuel for it to run. If the carb is fine you need to go deeper into the engine. Is the ring sealing? Do you have good compresion?

Do you know if this is a reed valve or a piston port engine?

My best guess is it is the carb.

pacodiablo · July 21, 2003

No clue. Tomorrow I will go in search of the proper screw and try again. I think I will also buy some engine gasket sealer stuff and make sure that the carb is sealed.

The SPEEDY · July 21, 2003

Haha, I knew Paco was back when I saw that topic. Sorry I can't help, not to good with two strokes, but the three most important things are, spark, fuel, and air. Make sure you have all of those.

timk49 · July 21, 2003

Yes of course gas can go bad. Six months is a long time in a can for gas. You can usually smell the lacquer smell when it goes bad. You know you messed up the carb seal and the screw. fix that first.

Good luck hope it works.

MCourson · July 21, 2003

I got this from a local karting site I frequent. Though it uses a kart racing reed valve it might help.

http://www.nfkc.org/2strokeexplained.htm

WEFs99 · July 21, 2003

The gas cannot go bad in that short of a time even with a 2 stroke. If it starts and runs momentarily then the carburetor is not supplying the fuel. Some engines have a Hi and a Lo speed mixture screw and some only have one. The basic adjustment is 1 1/2 turns counterclockwise from closed. Be sure your float level is correct.

JonesNTN · July 21, 2003

Sounds to me like it is running too lean. The carb is allowing more gas to pass through than is being supplied by the tank. Check the fuel line for leaks, pinholes, or trash in the line. Also if there is an In-line filter, make sure it is clean.

WEFs99 · July 21, 2003

Sounds to me like it is running too lean. The carb is allowing more gas to pass through than is being supplied by the tank. Check the fuel line for leaks, pinholes, or trash in the line. Also if there is an In-line filter, make sure it is clean.

This is a good point about the fuel line on an elderly engine. Homolites were infamous for getting pinholes in the fuel line with age. They would get enough fuel to start but not keep running. Paco....buy something new!