I would carefully file it flat, fill the low spots with JB weld, then file again. It looks like someone chiseled the case halves apart. That hole looks like it could be an oil passage, so I would play it safe.
That's disgusting, isn't it? Man, POs can be incredibly barbaric in their methods... between half-destroying surfaces and covers to over-going the engine with mass amounts of RTV, they can be our worst enemy
I got this engine half disassembled with my first Nighthawk. Head and cylinder we're removed and the case was "split" with the rotor still attached and obviously the stator bolted on. Some peoples kids.
Yep... I hate to re-quote it, but the CMC video of the top end tear down on a DOHC 450 is a good example of how even those regularly involved in this stuff can take a wrong approach and use tools that one should never use on precision surfaces... so it isn't always the damn POs
I've been using J-B Weld High Heat Epoxy Putty for engine case repairs. Easy to slice a small amount off, knead to mix and apply. I found that a rough sizing part way through its cure works well then a final finishing after curing. It holds a very good edge.
I have a flat piece of granite from a sink cutout .... granite shops give them away.... and stick a round 12" disc from a disc sander onto the granite. The sanding discs are cheap and easy to find. Beats hand filing for accuracy and speed.
A forum community dedicated to Honda Twin cylinder motorcycle owners and enthusiasts. Come join the discussion about performance, engine builds, classifieds, modifications, troubleshooting, maintenance, and more!