I am in the process of pulling my flywheel to replace the ring gear on my 12.5 HP B&S. Before I bought the mower I think the previous owner let it set outside in the weather. The flywheel has a heavy layer of rust all the way around. Is this what is causing me to have to crank for a while before it starts. If I sand this off will I damage the flywheel and how would I readjust the gap between the flywheel and magneto? It seems like I remember years ago using a macthbook cover between the flywheel and the magneto to adjust them. Any help greatly appreciatted. Thanks rdan

Doubtful as far as the hard starts go. Rust has no affect on DC voltage. The only thing that can be a problem in that area is rust that has built up until it contacts the magneto. Even then it usually gets knocked off and isn't a problem. Sanding the flywheel is fine, set the clearance to .010 or a business card, don't look for this to help.

A few more details about how the engine acts would be helpful. Does it run fine once started? It could be that the choke is not engaging fully.

Mike

sounds like my oldy..... a little bit on full choke, and it'll start up, that is your using choke? the rust really doesn't do anything any harm...... except make it rusty.

Rust has no affect on DC voltage.

I think you meant to say rust has no affect on a magnetic field here. As any welder can tell you, rust does have an affect on DC voltage and amperage because it acts as a resistor.

No doubt you are right bbnisson. Wrong terminology but at least what I was attempting to get across was right. The rust on the magnets or magneto coil will not affect firing.

I will have to tell you, when it comes to electrical anything I don't follow it. I can read how the magnets pass the coil and it develops a field of some sort da de da....I can't see it, I can't follow it.

What is great about forums like this one is together we all = an expert.

Mike