Wade's Ratbike Page

INTRODUCTION
Rather than take the easy route and buy an SV650 or other newer bike to race, I've taken the path of modifying my EX-500 to accept decent tires. There are numerous ways to do this, but in my case it meant putting a late 80's Kawasaki Ninja ZX6-swingarm and early 90's Honda F2 (CBR600) front end on my EX500 frame. The details of the suspension modifications can be found on the Rear end and front end information pages.

THE FRAMES
I stripped down two EX-500 frames: one silver, one black. Actually, I stripped three, but one of them didn't sit even close to square on the floor, and I couldn't bolt the right-side frame rail into it without using a come-along to pull it into shape, so I decided to retire it from active use and instead use it for welding practice. Then I cut the rear subframe off one of them (the silver one) with my little air-cutter and trimmed the seat-braces to fit the new shorter tail. This process took the better part of a whole day, much of which was deciding which parts I *really* wanted to cut off and measuring things from side-to-side (I kept reminding myself to measure twice and cut once....)

Here's my newly nearly finished ratbike, before any painting...It has a ZX6 swingarm, penske shock, F2 wheels, tiny rear caliper from a dirtbike, an abbreviated (sub)frame, cross-bracing on the top frame-spars (under the fuel tank), F2 forks, GP shifting pattern, slightly abbreviated wiring, pod filters, and muzzy exhaust.

The frame was abreviated with a die grinder / cutoff wheel. Pieces cut from the discarded portion of the frame were welded in as braces for the seat. No EX is complete without a piece of wood on it somewhere. I used wood in the tail-support, since that was the easiest thing to shape to fit the tail. A small Rubber-Maid jug is strapped under the tank-mount, with hoses routed to it from the radiator overflow, carbs, crank breather, and battery. A sheet of rubber is tied to the top of the seat-bracket to reduce cracking of the tailsection as I move around on the seat.

I cut several sections off the now useless tail, and practiced welding them to a twisted/dead frame that I had in the garage. There were LOTS of ugly welds, but they eventually seemed strong enough to do the job: now I can't knock them off easily. That's a plus. With my little Mig, using Ar-CO2 gas, and 0.24 steel wire, I need voltage on HIGH (4 of 4) and the wire feed at about 3.5 (on a scale of 1-8, I think).

Here's the angle-iron I welded across the top frame spars.

I'm particularly happy with my GP shifter: I had to cut the top arm off the shift-lever, and weld it onto the bottom (at an angle). Some bikes only require that you flip the arm on the transmission shaft over, but the EX frame got in the way of that simple method.

Most solid motor mounts that I found for sale were of the two-piece variety, replacing the each long bolt in front/rear with two shorter bolts. This design strikes me as producing extra stress on the case bosses, so I decided to make solids that use one long bolt. This required fabricating a fairly precise spacer to fill the gap between the motor-case bosses in the front and the lower rear bolt location. I discovered that not only were the facing lands inside the bosses *not parallel*, the gap between them varied from case to case, so that I was forced to fabricate custom spacers for each case I intend to run. This variability makes mass-produced single-bolt solid mounts essentially impossible, IMO. The second set I made required about 1 hour of lathe time, and 20 minutes of filing and fitting for final assembly.

A picture of my little lathe / mill unit

Things I've learned about my lathe (or any lathe):

Make sure you turn the switch for the jaw-drive the right way, otherwise the piece rotates backwards, and interacts with the tooling in an odd fashion.
Little chips are easier to clean off the part/tooling than big spirally things.
Chips stick to greasy ways and drive-screws very well.
I have a Morse-Taper #2 in the lathe tailstock and the turret.
There's very few choices for #2 Morse-Taper tooling. Much hunting through tooling catalogs was required, but I have found and ordered end-mill holders for three common sizes.
The T-slots in my table are very small.
The clamp-set for my very small T-slot table is twice as expensive as buying a set in the typical Bridgeport table size.
Metric measuring tools work best to make parts to metric dimensions.
Good light is important.
Lathes are pretty simple: they can be disassembled and reassembled easily.
Moving the tooling very slowly makes smaller (more manageable chips) and a much nicer surface finish.
Three-jaw chucks have to be assembled correctly in order to center the workpiece.
Make sure the part is really tight in the chuck before you apply serious bit-force to it....D-oh!
Table-mounted toolposts on combination machines have less flexibility than toolposts on true lathes.
Buy a live center, and toss the dead-center that comes with the cheap tooling package.
Drill bits in large metric sizes are hard to find.

Anyone buying a mill/lathe should consider the cost of tooling. The larger industrial sized stuff (R8 spindles and #3 or 5 Morse Taper) are much cheaper than the #2MT stuff my machine came with, as a result of volume, I presume. I think anyone will eventually want:

a live-center set (with several tip styles)
a 1/2" drill-chuck
a decent boring head with bits
some end mills (I bought only a couple sizes 1/2, 3/8, and 1/4 I think, so that I only needed to buy a couple of collets...these were pretty expensive for the #2MT and took some hunting to find)
a set of carbide bits (Mine required BIG 3/8" or 1/2" square bits)
a set of clamps for the mill-bed (the T-slot size is important here, standard Bridgeport stuff is cheapest, but doesn't fit mine, so my clamp set cost $74 instead of $23
a spindle extension so that an end mill in the spindle can reach the table (I still need one of these, if I want to mill something thin, I have to clamp it on top of a 6" I beam so the mill can reach it).

-------------a colorful spacer bar-----------

| TOP | HOME |

Last modified on 05MAY2000