# Is my rusted flywheel causing slow starts?



## rdan (Aug 22, 2005)

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


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## mikemerritt (Dec 6, 2004)

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


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## bugman (Aug 12, 2004)

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.


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## bbnissan (Nov 7, 2004)

mikemerritt said:


> 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.


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## mikemerritt (Dec 6, 2004)

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


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