I'm trying to replace the rear fender on my 1987 CBR1000F with that from a 1990. Does it fit on top of or under the frame rails?

 

The rear inner fender/battery box is under/inside the rear sub frame. Are you sure a 90 model will fit under an 87? I think they are different.

 

They are very different! But I trimmed the 90 model fender to get a good fit. I was able to keep the original 87 fender with a 170 rear tire but when I went to a 180 it would not work anymore. I will post some pics when I figure how to do it.

 

Fender mod completed some time ago but hadn't had a chance to post photos.

 

That is a neat looking job. Looks factory, well done.

 

It came out better than I thought after starting. I was hoping for an easy plug and play fit. But found myself hacking/cutting and drilling with time constraints (work, daylight and weather). No garage working outside ☀️☔️⚡️🌙💨⛅️.

I'm posting from my phone and I can't figure how to post more than one photo per post. Sorry! View under tail section.

 

So thanks Jarvid,
I wish I could have recorded the process to benefit others but it was a rushed project and I was figuring it out as I went.

One key point: the battery boxes are also different and complicates the process. The fender attaches to the battery box. I chose to keep my stock box, which necessitated some way to attach the front end of the new fender. I thought that was better than replacing it.

From there it's trimming (thoughtfully/carefully) enough of the sides from the fender, for it to tuck up inside the frame rails into the right position, and attach the back end.

Hope that helps.

 

Nice job.