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Duraforce Rebuild

4475 Views 12 Replies 6 Participants Last post by  LawnBoyDoc
As I was telling Sharkey earlier today, I am knee deep in my Duraforce rebuild. Its all apart and cleaned and I am just about to do a very very light hone on the cylinder for the new rings with my Flexhone (4 passes and one or two fast for cross hatching). I have pics I'll post later tonight, but it appears that the motor sat in a very humid environment or it was watered. Seems the bottom crank bearing had a bit of rust on the lower outside of the crank lip and partially on the bearing casing-couldn't see any on the ball bearings. I cleaned and oiled the crank bearings (both top and bottom ball bearing); the top crank bearing is butter smooth, the bottom crank bearing turns easliy-but it just has a "feel" to it. No where near as smooth as the top bearing.

What to do? It appears the Duraforce crank is ONE STOUT piece. BIG ball bearings!!. And although the bottom one seems a little less smooth it has no more free play than the top one. I don't think I could bend or hurt these bearings with a sledge hammer. Has anyone heard of a Duraforce crank bearing failure??

Also appears that the bearings and crank are one unit. Bearings are not...sold separately ($80.00 for the whole unit at mowpart). Anyone have any experience you can put me at ease or tell me to take out the wallet. :crybaby:
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I would put it back together and give it no more thought if they are tight enough to please you. DF cranks are tough units, it's the rod bearings and aluminum rod that concerns me. The DF mains are an improvement over the F series IMHO. After honing, check for burrs on the port edges as they can rough up a new set of rings and piston if they have a burr or sharp 90 degree edge. A wide port can have a ring bulge out into it a tad and catch the sharp edge. A small riffler file will do the trick of knocking off the sharp edge. Good luck!
Nice pics, I don't see any deal breakers there, steel wool with do a good job of removing surface rust. The piston is not that bad either, but I like fresh ones with new rings and seals. You should have a runner there soon. Keep us informed.
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