Restoration Yamaha LS3 1972: January 2015

A while ago I bought two sets of cadmium plated spokes with chrome nipples. But I was still waiting for the spoke spanner so when it arrived last week it was time for a rear wheel make over. The rusty spoke nipples had been soaked with WD40 for a couple of days so with my new spoke spanner it wasn't to hard to take 'm apart. But... before I took the spokes out I made a couple of pics of the way the spokes were laced. Luckily I didn't took the front wheel apart at the same time. This way I could use it as a reference when lacing the rear wheel.

Checking the wheel for offset Yamaha 100cc LS3

Checking the wheel for offset (there's none)

Removing the old rusty spokes Yamaha LS3

Removing the old rusty spokes with a spoke spanner

Inner spoke (left) and outer spoke (right)

Wheel Yamaha LS3 dismantled

Some wheels have an offset; it means the hub is not exactly in the middle of the rim. The Yamaha LS3 wheels don't have an offset. If you take a closer look at the spokes you'll see that they are in groups of four, the LS3 wheels have 36 spokes thus 9 groups of 4.

First I started polishing the hub, way easier when the wheel is apart ;) First I sanded all the aluminium parts with 400 grit and used WD40 as a lubricant so the sandpaper wouldn't clog within a minute.To make things easier I put a spindle on my grinder so I could install buffing wheels. Normally you use those compound sticks but I found out that buffing compound which I used for cutting, buffing and polishing new acrylic paint works as well or maybe even better. Just put some on your buffing wheel and start cutting and polishing.

Hub rear wheel Yamaha LS3 1972

Grinder transformed into a buffing machine

Polishing the aluminium hub Yamaha LS3

Polishing the aluminium hub with Farécla G3 and G10

Now it was time for lacing the wheel... BTW I bought 2 new rims (original Yamaha) for only 40 dollar each. When I got them I was a bit disappointed because they weren't the original ones. There was no stamped name of the rim factory "Takasago" in the rim. Other than that the size is the same and the quality is very high. Re-chroming a pitted rim will cost you around 300-400 dollar if done properly. So I keep the old original rims and when I hit the jackpot I can always choose for the original option. Anyway..

New 18" Yamaha rim

New Yamaha LS3 18" rims

Start with the inner spokes on one side. The inner spokes have a around 45 degree bent while the outer spokes have a 90 degree bent. If you take a closer look at the rim you'll see the nipple holes are each in a different angle. Check your pics or reference wheel for the right one! After you've found the right one, count four holes and fix the second spoke and so on till all 9 spokes are in. As soon as you put the spoke through its hole-mate in the rim put on the nipple so it won't fall out. At first tighten all the nipples 3 threads, or 4 or whatever as long as you do the same with each spoke. This will be very handy when truing the wheel later on. After the first nine inner spokes are in, start with the nine outer spokes on the same side. Then flip the wheel fix the inner spokes and then the outer spokes on this side.

Old and new Inner and Outer spokes Yamaha LS3

First inner spokes are in, using front wheel as reference

First set of inner spokes are in

Halfway the second set of inner spokes

Rear wheel Yamaha LS3 with new spokes

Spoke nipples Yamaha LS3

Now start tightening all the spokes the same amount till you can't see any thread on the spokes. You can feel they're getting tight now. Time for some truing... Truing?? That's how they call taking out the vertical and horizontal wobbles. I found out that an axle stand has the same hole diameter as the axle diameter of a Yamaha LS3, so I could use this as a wheel stand.

Truing the wheel with a dial gauge

Using the spoke spanner (size 10) to tighten the spokes

Start with the vertical truing, this will make the horizontal easier. I used a dial gauge, but if you don't have one you can also use a piece of wire. Look for the lowest spot when turning the wheel and put the dial gauge at this point at zero. Now turn the wheel until you find a high spot, tighten the spoke on this high spot and the two spokes left and right of it, a 1/4 turn for each spoke. If the spokes are too tighten loosen the spokes opposite of the high spot. You have to do this for a couple of times till the max. plane is 1/16" (1.6 mm). I used masking tape to mark the high spot I was working on, this will make it easier to find it after turning and checking the progress. Now start with the horizontal truing. It's a bit time consuming but after a while you'll get the hang of it and know exactly what to look for.

A horizontal run out of 6.4 mm before truing

1.2 mm vertical run out

After truing an acceptable 0.4 mm horizontal run out

Truing explained in Service Manual Yamaha 100 LS3

After I took the bike apart I started to take all the rust and old paint off with a brass wire brush mounted on a grinder. A very slow and dirty job to do, it took me around 8 hours and 3 wire wheels to bring it all back to bare metal.

Rusty frame Yamaha LS3

Brass wire brush wheel

First parts Yamaha LS3 back to bare metal

Frame Yamaha LS3 back to bare metal

Finally all frame parts back to bare metal

I painted the frame with POR15, and on top of that a tiecoat and Hardnose, a two component coating (also from POR15). POR15 will prevent the frame from rusting again and the Hardnose paint is a tough UV resistant topcoat.The 2 coats of POR15 went on really nice and smooth, almost like a spray paint finish. The Hardnose paint also looks good but in some parts it was a bit too thick so I had to sand it back and repaint it. The trick with these moisture cured paints is to paint as quick as possible without going back to already painted parts. If you go back the paint won't flow very nice anymore, it will dry a bit bubbly and you'll see brush marks. It sounds easy but a frame has so many sides, corners and hard to reach spots that the reality a bit different. Also, don't use the cheapest brush you can find, believe me I've seen the difference in finish and you'll get way better results if you use a brush a bit more expensive.