Probably a one off, but if a heads up helps anyone ..
Had a meltdown couple of weeks ago (the 87 VR & me). Noticed the back half plastic fins on the right side-vent were warped. man was I pi@@ed, anyhoo, this was the only symptom of the motor overheating. it was extremely hot combined with city driving must have launched the motor temp. Temp gauge held steady slightly above normal on the green entire trip. (still don't understand why the temp gauge didn't redline) Didn't notice the fan cut in at any time, not to say it didn't, it is functional. There doesn't appear to be engine damage.
Long and short of it, found the top of the 2 part front cylinder head cover/heat deflector had come apart and partially slipped forward between the front cylinders and the rad fan. The upper cover is secured to chassis frame by friction fit and connect to each other by a rubber channel and a dozen interlocking male/female rubber prongs. Repositioned covers and end of problem methinks.
Checked front cylinder head covers this morning. Sure enough, they're separating slightly at the rubber channel. Reseated again, maybe zip tying them together would be one fix. Hope I'm on the right track here.
left fin in image is normal. tough getting decent pics of the cyl covers.