Introduction: 1993 EX500 Race Bike - Complete Rebuild
Hey everyone, I picked up an 1993 EX500 in pretty rough shape at the beginning of last summer for a project bike and decided to document my progress. Here's the storyline of the complete overhaul, restoration and modifications.
It's a 1993 ex-race bike. It has an FZR600 front end and a 1986 ZX6 swingarm with an FZR600 18" rear wheel. The previous owner lost the ownership and the bike wasn't running when I got it but it would crank. It was a bit of a mess but I ended up getting the ownership for it and started the rebuild process.
Any feedback is appreciated!
Disclaimer: I should add that I am not a licensed mechanic just a backyard hobbyist. Read what you see here with that in mind. I assume no responsibility for your safety.
Step 1: Step 1: Teardown
The first thing I needed to do was tear the bike down to see exactly what I was working with. It was at this point that I realized how much of the bike wasn't stock.
FZR600 front end
1986 ZX6 swingarm
FZR600 18" rear wheel
Step 2: Step 2: the Chassis - Rear
After tearing the bike down I noticed how rough of a shape the rolling chassis was in. The swingarm had been fitted improperly and wasn't aligned, the dog bones had been cut and re-welded, and the front triple tree was bent.
After quite some research I found that the swingarm swap was a common one (although the 18" wheel in there wasn't) and found some information on how to do it properly. It turns out all the spacers needed were there but were just fitted in the wrong order.
Once I reinstalled everything in the right order and replaced the rear master cylinder and brake line the rear end was starting to look pretty good.
Step 3: Step 3: the Chassis- Front
On to the front end. Here we had the forks and wheel from an FZR600 and the original EX triple tree with the FZR step welded into it. In addition to this cacophony of parts, I noticed that the forks weren't parallel. Off comes the front end.
The first culprit was the triple tree. I was debating whether or not I should be trusting the welded stem when I realized that the lower triple was actually warped. This made my decision a bit easier and I tossed the whole thing. To replace it I decided to use a stock FZR triple tree and source the correct sized bearings to adapt it to the EX frame.
With all that installed I checked to see that everything was aligned and found that my forks were true and undamaged :)
Step 4: Step 4: the Engine
This was the most comprehensive top-end overhaul I had ever done. After reading a bit about these bikes I found out that they had a tendency to warp heads due to their thin design. What this meant was that if I planned on pulling the head it would have to be lapped. Since I had no idea what condition the engine was in I decided to go ahead with the whole top end rebuild including:
Cylinder lapping & Head lapping
Lapping involves using a lapping compound (abrasive paste) to bring the clearances between parts back to spec. For the cylinder and the head I used a large piece of scrap granite ($5 from a counter top installer) with a piece of plate glass on top (the flattest thing I could find within budget). I applied the compound to the glass plate and used that as my lapping surface. You're supposed to keep even pressure on the part you're working with and move it in a figure 8 pattern.
The valves are a bit easier. Just apply some lapping compound to the valve seat and twist the valve back-and-forth to re-cut a nice grove and improve the seal.
After doing this make sure to thoroughly wash all parts to remove all of the abrasive material. I found Varsol worked best.
Head gasket restoration
I had a head gasket that was in decent shape still so I just cleaned it up and reused it. I read a tip to spray paint both sides of the head gasket with some engine enamel to help create a slightly better seal. I'm not sure how accurate that is but I gave it a try.
Piston ring replacement
This is a fairly standard part of any top end rebuild. Replaced the piston rings with standard sized OEM rings.
I took the cylinder to the shop to get it honed.
Valve clearance adjustment
The EX500 uses adjustable rockers rather than the bucket+shim setup I was used to. I'm not a big fan of this because I always feel like I'm off by a bit when making adjustments. Basically the idea here is to loosen the locking nut, adjust the rocker position and re-tighten the nut.
More notes in the pictures :)
Step 5: Step 5: Custom Tail
At this point the bike was running well and I had the integrity of the chassis sorted out. On to the cosmetic.
In my opinion, one of the ugliest things about the older generation of motorcycles is the fat tail fairing. I wanted to do something about this for my project.
First I removed everything in the rear that could get in the way of me cutting and welding (wiring, wheel, brake lines, electronics, etc.) With that stuff out of the way, I started marking off different possibilities for the tail. I quickly realized that simply cutting the existing fairing would not work so I divided the task into 2 parts: Subframe Modification and Fairing Design.
I had never done any body work before so I was a bit apprehensive about diving into this head first but how else was I gonna learn :P I started with what I knew: Paper Mache! I bought some thin wire mesh that I cut and shaped into the generic shape that I wanted and coated it in a few layers of paper towels. Once I had a shape I liked I covered it in Bondo and started sanding away.
After the bondo phase I was left with a tail fairing that was close to what I wanted and weighed a ton. At this point I covered the whole thing in duct tape, coated that in some deodorant (cheap lubrication tip I picked up online to help separate the mold) and fibreglassed over top. At this point I just pulled out the mold from underneath the fibreglass (crushing it in the process) and was left with pretty much my final part.
This whole process involved a lot of experimenting and a LOT of work. I'm still not sure how to do this kind of thing properly but one suggestion I would make is to get one step perfect before moving on to the next. Little imperfections from the start build up rather than get cancelled out :(
This was the less reversible of the two tasks so I left it to the end. I basically just wanted to get rid of the lower subframe rails that sat reallly low (below the top of the rear tire even). I cut off the rear of the subframe, took out a section of the lower rail and rewelded them at a steeper angle to still support the weight of the rider.
Step 6: Step 6: Relocation
As a result of my custom tail I no longer had room for a LOT of stuff that was hidden under those huge panels. Time to relocate.
New Tail, New Tail Light
I had a sleek modern tail light lying around from another bike that I just knew I had to use. I fabbed up a few mounting tabs for it and it ended up working pretty well with the tail too.
The biggest issue was relocating all the electronics that were previously under the seat, between the two subframe rails or tacked haphazardly onto the outside of the bike with no regards for aesthetics. I cut off all the previous mounts for them and started looking for new spots to put them. Most of them ended up going back under the seat but they did require a few extra support beams.
Relocating Everything Else
With the electronics sorted I still had a few more things to move around. Since I used the FZR triple the ignition switch no longer fit properly and the coolant reservoir had no chance of fitting under the tail. I managed to relocate the ignition switch between the rails of the frame but for the coolant reservoir I needed to come up with something new. I ended up using an aluminum water bottle with a couple of fittings. It's not the prettiest solution but it's not terrible either. It'll serve the purpose for now.
Finally I needed to modify the airbox a bit because it no longer fit between the subframe rails. I marked the spot where it interfered and cut the section off of the covers. I made up a few pieces to close off the hole from abs plastic and glued them in place.
Under tail + Dash
I had no intention of keeping the ugly stock dash, birdcage, headlight assembly so I started coming up with a few ideas for a replacement dash using some paper card. I never ended up completing this but here's how my final design looked. I intended to use one of the small, digital Trailtech Vapor gauges (heard nothing but good things about them).
Finally with all the subframe modifications I needed a new undertail to cover everything up from the elements. First experimenting with some paper card, I eventually transferred my design onto some light gauge steel sheet. In the end I was planning on getting one fabbed up using some thicker material or maybe fibreglass but I ended up moving and selling the bike before I was able to finish that.
Step 7: The End
Well that pretty much summarizes my EX500 build/restoration. At this point I had a running bike on a nicely set up chassis. Considering the amount of modifications, it was a pretty unique bike too. Unfortunately I was moving and had run out of time to work on my project so I ended up selling it. Hopefully it's still out there somewhere in the hands of another gear head :)