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Fork Drain Holes

Drilling and tapping fork legs for drain screw installation for 94+ Concours:
Disclaimer: The procedures and suggestions presented in this article are solely those of the author. C.O.G. and Kawasaki Motors Corp. USA neither recommends nor endorses any motorcycle modification, which might adversely affect rider safety. Any modification that may be safety related should only be done by, or under the supervision of a qualified motorcycle mechanic.

Note: The recommended way to accomplish this is with the forks removed and completely disassembled so you can flush out any debris from the drilling and tapping of the holes.

I purchased the hardware and tap from my local hardware store. I don’t know if a Lowe’s or Home depot would have the hardware. I also considered buying the hardware from Kawasaki, but I figured the cost would be more than the $5 or so I spent. The screw is a pan head, 5mm – 0.80 by 10 mm long. The tap (same specifications) was a tapered tap, not a bottom tap. The drill bit called for the tap is an 11/64ths but I used a 5/32nds (next size smaller) to get a ‘deeper bite’ with the tap. I utilized a fiber/phenolic type material washer; 3/16 i.d., 7/16 o.d. 1/16 thick.

(I’ve been told a M5.0 X 0.8 and 10-32 are almost an exact match and can be used interchangeably. I personally have not verified this)

As an alternative, American hardware, an 8/32nds X 1/4" pan head screws could be used. An 8/32 tap calls for a # 29 drill bit.

I used a hand held cordless drill; a drill press would be more precise of course.

1. On level ground securely jack up and support (under the crankcase) the front end of the motorcycle with the front wheel off the ground. Make sure the wheel is high enough so it will clear the front fender once the axle is removed. Remove the front wheel brake calipers, brake line guides, speedometer cable from the wheel, the front wheel and the front fender. Remember to support the calipers with cable, string, bungee cord to keep them from hanging by the brake lines.

2. Turn out (counter-clockwise) the spring pre-load adjusters until they stop. There is a cotter pin internally on the end of the adjuster so it will not come all the way out. Prior to loosening the caps, make sure ALL the top pinch bolts are loose. These include the two (per side) top clamp bolts, and the Allen head cap screw in each of the bar risers. If these are left tight, the tubes constrict around the threads and keep them from turning easily and thread damage may result. Slowly remove the fork cap, use caution; it is under pressure from the fork spring. Remove any zip ties securing cable, lines or wiring to the fork tubes; remove the forks from the motorcycle. Disassemble the forks as per maintenance instructions.

3. Centered on the back side of the fork leg is a casting parting line; this is where I drilled mine at. From the bottom of the fork measure up 2 7/8", or 73mm for metric, and mark the spot. (I used one of those liquid paper correction pens to mark the spot.) 
Then with a flat file I filed the surface flat mainly to have a good surface to mark with the center punch and also to provide flat sealing surface for the screw.

Re-measure the 2 7/8" and mark/center punch for drilling and tapping.

Drill and tap the threads, flush out any debris from the fork legs.

4. Using some type of anti-seize or sealant such as Teflon liquid, a silicone or Permatex type 2 (non-hardening), now install the drain screw and washer. Utilize extreme care when tightening the screws, the fork leg is aluminum, the screw is steel. It would be easy to strip out the threads you just worked so diligently on.

5. Reinstall the fork tubes, fender, front tire, and add fork oil to the proper level as per the maintenance manual

Note: These next two steps are a great tip for anytime you have re-moved your fork spring caps and are reinstalling them. Reinstalling the caps sometimes can be "challenging", don’t be under a "time crunch" if possible. If you can’t get the threads engaged and you start getting frustrated, take a break and then come back to it. Those threads are a fine pitch and can get damaged easily. Though the cap is probably not too expensive to replace, the fork tube might cost a bit more, plus I doubt anyone has them on hand.

6. Prior to reinstalling the fork springs, make sure all the upper pinch bolts are loose, the lower pinch bolts should be tight to prevent the fork tubes from spinning. Begin to install the cap(s) (no springs or washers in the fork tube) and make a note where the threads just begin to engage (catch). Index this on the cap, with a magic marker line, to a fixed point of reference such as the split in the bar riser. Keep the cap(s) with the tube you indexed it on.

7. Replace the spring and washer. Using a speed wrench makes the installation of the fork caps relatively easy. Using the speed wrench, align your mark on the cap to your point of reference, turn the cap CCW about 1/8 of a turn. Then push down, and holding the cap straight going into the bore of the tube. Find your point of reference, slowly turn the cap CW until the threads catch (your mark on the cap and your reference point should be lined up) keep turning at least 1/4 of a turn past the reference point then carefully relax pressure slightly to insure the threads are engaged. If the threads are engaged, tighten the caps on down.

Vic Salisbury
Cog #3673
'99 Connie "Taz"

Article By: Vic Salisbury

Original January 2007 

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