Question for you experts.

[aka rotten]

Have a WHITE made by MTD,Need general engine ?.15HP,MOD.28707,TYPE,013701,CODE,940907.What would cause engine to turn very slow when trying to start. Cranks fast when plug is out?I,I,ve not seen this engine run myself,but lady that owned it said ran fine when she parked it do to front end problems last year.Been covered up since.Valves possabilly?Thanks.

 

[ironnut]

Assuming it is an overhead valve engine, check the valve lash. The automatic compression release lifts, I believe the exhaust, valve a tiny bit to reduce the compression. If the valve lash becomes excessive then the excess lash takes up the compression release movement and the valve doesn't actually. The starter typically struggles and batteries and starters get replaced and the problem persists. My neighbors JD riding mower has a single cylinder OHV engine of a similar HP rating and it has had that problem a couple of times.

gordon

 

[DFB]

Starter relay specifically a poor frame ground. My twin cylinder MTD had similar problems battery was good, valve clearance ok bench tested starter that was ok too. Temporarily grounded relay with heavy jumper cable...zoom zoom! Saved me from buying a replacement part too!

 

[PILOON]

Check all battery contacts and all grounds. Corrosion has a nasty habit of affecting contacts = starting issues.
You want shiny metal to metal contact. Remove, sand paper and re attach especially grounds.

 

[SandburRanch]

Have the battery load tested. If it tests ok then check/clean the terminals if the problem persists.