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Small engine repair question

DaveNay

DaveNay

Klaatu barada nikto
Last winter I picked up a riding mower with a 14.5HP B&S engine. I only paid $100 for it, because it was very difficult to start. Today, I am trying to tune it up, with no success. Here's my problem....I put a new battery in, and it turns over a little better, but it will only turn the engine about one turn, then it binds up and struggles through about 1/4 turn, then turns freely again. I changed the spark plug, with no difference. I then removed the spark plug entirely, and cranked it, and it easily spins the motor with no problems.

So here it is...

  • New Battery
  • Electric Start
  • Fuel flow confirmed to carb
  • Very difficult cranking under compression (plug in)
  • Cranks easily with no compression (plug out)
  • Plug has fuel odor on it after removing - fuel making in to cylinder.
Any help is appreciated.
 
Pull the flywheel and replace the index key. Sounds like a sheared key that is causing the timing to be off. You will need a special tool to remove the recoil mechanism from the shaft, or you can try to "shock it loose" with a flat blunt object such as a large bolt. Strike against each rib until it comes loose. Be careful not to break the aluminum casting. The tool is about $20. The part was also about $20 the last time that I needed one, so it is a gamble. I now own the tool... Junk...
 
Junkman said:
Pull the flywheel and replace the index key. Sounds like a sheared key that is causing the timing to be off. You will need a special tool to remove the recoil mechanism from the shaft, or you can try to "shock it loose" with a flat blunt object such as a large bolt. Strike against each rib until it comes loose. Be careful not to break the aluminum casting. The tool is about $20. The part was also about $20 the last time that I needed one, so it is a gamble. I now own the tool... Junk...
Click to expand...

Thanks Junk, I will certainly inspect that key....no recoil mechanism, it's electric start.
 
Junkman said:
Pull the flywheel and replace the index key. Sounds like a sheared key that is causing the timing to be off. You will need a special tool to remove the recoil mechanism from the shaft, or you can try to "shock it loose" with a flat blunt object such as a large bolt. Strike against each rib until it comes loose. Be careful not to break the aluminum casting. The tool is about $20. The part was also about $20 the last time that I needed one, so it is a gamble. I now own the tool... Junk...
Click to expand...


No joy...when I removed the fly wheel retaining bolt, I could see that the key is still in perfect condition and alignment.

Something seems wrong with the compression to me....I checked closer, and it will crank easily about 1-3/4 turns, and then has difficulty for 1/4 turn, then repeat.
 
See if it changes when the plug is in and the plug wire is disconnected. If it spins easily. The put the plug wire back on, and if it is again "tight", then it is a spark timing issue. Also try some ether and see if that will get it started. If it will run on ether, it should run on gasoline.
 
Junkman said:
See if it changes when the plug is in and the plug wire is disconnected. If it spins easily. The put the plug wire back on, and if it is again "tight", then it is a spark timing issue. Also try some ether and see if that will get it started. If it will run on ether, it should run on gasoline.
Click to expand...


This thread describes my problem precisely, and seems to have a solution. I just don't know if I can adjust the valves myself.
 
OK...adjusting the valves was easy....once I went out and bought a new set of feeler gauges. Why can I never find stuff like that when I need it?!

The engine now starts good, but now I keep blowing fuses. Someone has been messing around with the wiring on this mower because there are a few things I don't understand....notably, there is a small gauge wire that comes from the magneto and runs into the wiring harness. This is in addition to the AC and DC wires near the starter for the lights and charging. Also, there is a anti-aftifire solenoid on the carb, but it has been disconnected. There is also a wire near the starter solenoid that is not plugged in to anything. :confused:
 
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