I purchased this 2013 DF175 with a damaged piston and cylinder head from a broke exhaust valve. The damage to the head can be repaired according to a few Machine shops I talked to but now I am looking into the actual cylinder which has some very light scoring on the cylinder walls. I have been looking around to see if it is possible to bore the cylinder and install a slightly over sized piston but it seems I can not find any details on doing such on these four stroke engines. It looks like the cylinders are cast iron sleeved but maybe they are nikasil and not able to be bored out? You can barely fill the scoring on the cylinder wall with your finger nail so it is substantial but possibly may could just be cleaned up with a light honing of the cylinder? I am not looking to take any short cuts and I want to get this motor going again so it will last so any advice would be great.
On another note, All the valves being white makes me think this motor was running a bit lean or maybe hot? The PO has not long replaced the water pump and done other services such as the internal anodes so maybe something failed and it ran hot? Motor only has 960hrs and the owner claimed it was serviced regularly but maybe not as it does seem there is a good bit of corrosion inside the water passages which may be way it ran hot. There is a layer of crust on the passages which may keep the water from contacting the aluminum to dissipate the heat correctly.
Thanks
Mike
On another note, All the valves being white makes me think this motor was running a bit lean or maybe hot? The PO has not long replaced the water pump and done other services such as the internal anodes so maybe something failed and it ran hot? Motor only has 960hrs and the owner claimed it was serviced regularly but maybe not as it does seem there is a good bit of corrosion inside the water passages which may be way it ran hot. There is a layer of crust on the passages which may keep the water from contacting the aluminum to dissipate the heat correctly.
Thanks
Mike
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