So I've had my XTZ for coming onto 2 years now and I started to hear just a little rattle in the valves and started looking into the best and easiest method to adjust those clearances. In reading the manual to see what they recommend I saw how slick AC's valve adjustment tool (part # 375-1000) looks to be. And then I found that the best price I could find it is being sold for is $112 at Country Cat. In looking at it for a while and doing some thinking about it I decided it shouldn't be to difficult of a DIY project and have just finally got around to tackling it...........here I will try to share the resulting efforts.
1st to find the size of the essentials. The lock nut is 8mm and I finally found that actual square head adjustment screw is 3mm. Finding a 3mm square driver was next impossible and then I found that it turns out that a Robertson (square) #2 screw head is 3mm!! This was making it tooooo easy.
So I gathered the parts.......here is a photo of the parts collected:
1 - 8mm deep 1/4" drive socket (I had a cheapie laying around but could find one at the pawn shop for a buck or 2)
1 - #2 Robertson (square) wood screw (left overs lying around)
1 - 1/4 bolt long enough to extend through the socket. Mine was long enough to cut off the NC threads so I could rethread it to 1/4-28 fine thread (in my screw drawer - no cost)
1 - 1/4-28 jam nut - (Happened to have a bunch of them from building airplanes......Lowes in Canada sells them 4 for $2)
1 - 1/4 rod ~6" long (I had some in my small scraps bin)
1 - 1"dia X 5/16"L Round Brass rod.......(a couple bucks at the scrap bin of a metal fabricator's shop)
I should 1st note that I decided right at the start on a few things that would make this project perhaps a bit longer to complete, but to me would have me end up with a tool that would be less "DIY Looking", and I wanted to be able to assemble the unit without welding spatter all over my shaft knob assembly. So Instead of welding the adjustment knob to a shaft I decided to make it threaded. I also was going to thread the lever handle into the socket, but found the socket too hard and didn't want to break off a tap trying to thread a hole, so I press fit my lever into a hole in the socket and then welded it. I also decided not to use loc-tite on my threaded knob, but to use a jam nut instead. This then added me not wanting a "nut looking" jam nut and so a little more lathe work.
I 1st took the 1/4 bolt, cut off the end with the threads and then with it in my lathe I faced the end and drilled a hole a bit over 1/2" deep. This hole was sized to be a press fit for the diameter of the screw shaft. I then cut off the screw at the appropriate length and then pressed it into the hole. I bevelled the end of the hole to allow the tapered head of the screw to fit snug. After I pressed the stub if the screw into the bolt I put the bolt into my lathe and turned the screw head down to a diameter that would fit inside the 8mm socket.
I could see that I had to drill the centre of the socket out to 1/4" so that the bolt would be able to pass through it. Even with the socket being 1/4" drive there is usually a smaller section right below the square part of the socket and this had to be enlarged. These sockets, even the cheap ones, are hardened and are pretty hard to drill out. I used lots of lubricant and it did the job.
I then decided to work on the adjustment knob. I turned a piece of brass down to aprox. 1" and then added the very important 8 marks for the adjustment increments. I had to think for a bit as to how to do this accurately and quickly came to a very accurate method using my lathe. I printed a circle with the 8 increment lines on it. I actually printed 16 increments but decided to use only the 8 as AC does. I then cut this out and glued it to the back of my lathe chuck. I then lined one of these marks up with a sharpened 1/4 rod pointer mounted to my lathe with a tiny rare earth magnet. Like this:
Then with the lathe spindle engaged in a low gear (so that it wouldn't move) I used a fine sharp cutting tool in my tool holder and then moved the cross slide to have the cutting tool hard against my brass and then dragged the cutter across the face of the brass. I repeated this drag 3 times for each line. I then rotated the spindle to the next correct mark and dragged the new line, and repeated for all the lines
Then before parting the piece off to it's 5/16" length, I added the knurl to the edge and bevelled the outside edges and drilled a hole with a #3 bit (7/32 will be close enough) and tapped the 1/4-28 threads. I then parted it off and faced the backside it for a nice finish.
Next I reinserted the bolt with screw in the lathe and using a 1/4-28 die I made the threads to match the knob. I made these threads long enough to be the combined length of the knob and a jam nut. Also, the 1/4 bolt I used was a tad too large of diameter to thread and so had to turn a few thousands down to be able to die it properly.
I then tackled the socket/lever assembly. As mentioned above, I found the socket too hard to want to tap. In fact, if doing so again I probably wouldn't even drill a hole to fit my lever into. Instead I would have concave shaped the end of my lever to match the socket and just welded it. Drilling holes in a socket isn't much fun ether!!! I couldn't find specs as to the length of the handle, so tried to guess by photos. Mine is just under 6 inches long. I did attach the lever on a bit of an incline..... Not sure that is necessary.
The last thing I did before final assembly was decide on what to do with my jam nut. I didn't like the look of the jam nut on top. It again looked too "DIY er"
So I tried it on the underside and still not 100% happy, and so ended up putting the jam nut on the end of a bolt and turned it to a bevel. I liked the look of it now and it actually gave kind of a bushing surface to turn on..
So the only thing left is to paint all the parts black.....Except for the brass knob!! Hope you all could enjoy the fun I had making this tool. For a couple hours work I had a lot of satisfaction and not bad hourly rate!!