Spocket/Chain Replancement

	Changing the Sprockets and Chain on 1997 Yamaha YZF 1000 ThunderACE



	Last weekend I changed the chain and sprockets on a fellow THUNDERACE List members YZF1000. It was good practice for the upcoming change I needed to perform on my own YZF1000. When doing my own, I decided to document the process so that others might follow along. Changing the original sprocket and chain is not a difficult process as long as you have the proper tools. Keep in mind, my bike has over 26,000 miles (approx. 36,000km) on the original chain and sprockets. I know this for a fact since I'm the original owner. Keep in mind that this bike has been ridden hard, participated in over 10 track days and generally been put away wet. I used to be very careful about keeping it as clean as possible but, I'm ashamed to say, that I have not kept up with it recently. Broken bodywork and a dinged frame has muted my desire for a meticulous looking motorcycle. I plan on restoring this YZF to it's former beauty soon. During this replacement, I am converting from the stock 532 size chain to a 530 size.
		The whole process starts off by removing the chain guard, shift lever and primary sprocket side cover. A 10mm box wrench is used to remove the shift bolt. Sharp eyed readers will notice that I have reversed the shift pattern. I don't necessarily recommend this pattern for the street but I like it for the track so I leave it that way for street duty.
		The primary cover is easy to remove with the exception of the middle bolt. My cheapie metric socket set was too large and wouldn't reach the bolt. I found a 1/4" drive socket that did the trick though

		This picture was staged, but I next removed the countershaft sprocket nut. A 3/4" impact driver helped to make quick work of this job. Without an impact driver, I could have used a ratchet and had someone stand on the brake to keep things from moving. In the picture at right, you'll notice the nut has a counter bore relief that allows the nut to hold the sprocket tight and still clear the output shaft.
		If you don't want to remove the swing arm, then the following steps are used to remove the chain. I used a large angle grinder (a drill mounted grinding wheel would work well also) to grind the heads off two of the chain pins. You'll notice that the chain looks pretty dry in this picture....that's because it is. I knew I was going to be changing the chain so I didn't use any WD-40 after the last ride.
		Since I'm building an airplane in my garage, I have all sorts of interesting tools that can help when removing the chain. I pulled out my 3x rivet gun and used it to drive out the pins. If you don't have a rivet gun or air chisel, then a good hammer and drift or punch would probably get the job done......eventually.
		With the wheel still on the bike, I used the impact driver to make quick work of the sprocket nuts. It's easier to remove these on the bike at this point.
		I then removed the rear wheel to take off the sprocket and install the new one. I got busy and before I knew it I was done and forgot to take any pictures. Sorry. While both sprockets were off the bike I took the time to examine and compare the condition of the sprockets. The rear sprocket shows obvious signs of wear as evidenced by the thinner sprocket teeth. I also took the time at this point to deburr the sharp edges around the teeth. I've chosen to stay with the stock size 46 tooth rear sprocket but the new one is made of aluminum instead of steel like the stock unit. The new sprocket weighs 1 lb 1.4 oz verses 2 lb 4.8 oz for the stock unit. That's a savings of over 1 lb 4 oz or more than 50%!!
		I chose to use a 16t front sprocket instead of the 17t stocker. You can see the difference between the stock (right) unit and the new one. The stock sprocket has some material bonded to both sides of the sprocket, I presume, to help cushion the chain and keep things smooth as it goes round and round. The replacement unit doesn't have this feature. My chain was so worn and was so rough that I'm sure it'll be tough to feel the difference. I didn't weigh the two sprockets (I forgot) but since they are difference sizes I'm sure the replacement is a little lighter although they are both steel sprockets. The picture on the right shows the extremely worn front sprocket. 125 HP tugging on that chain and sprocket for 25,000 miles can be tough on the sprockets. This is an extreme example of why you should change the sprocket and chain together.
		Even though my bike is not the best example of cleanliness, this is probably how dirty the counter shaft sprocket area will get on virtually every Ace out there. The shiny clean rear wheel sprocket looks out of place on my dirty bike. The sprocket has a relief machined in it so the proper number of threads will show when installing the sprocket nuts. I really need some new foot pegs and rear sets. Anyone have a set they want to donate to the cause?
		All that's left is to install the D.I.D ERV gold chain and and install the master link. My aircraft tools will come in handy for that task as well. The ERV chain is for racing and a step up from the street version. This version can be distinguished by the solid gold links instead of just the gold outside plates.
		This is a picture after the sprocket area has been cleaned up a LITTLE. I never knew there were plastic pieces in there. The wires go to the neutral indicator switch and the plastic piece on the shift shaft is just a spacer.
		This chain only came from this dealer in 120 pin lengths so I had to cut some of it off using the same technique I used to remove the old chain. You can see the grinder at work on the right picture. For me, it's just as easy to do the work on the sprocket. This way I don't have to try and balance the chain on the vise while I grind and drive the pins out.
		After shortening the chain I lubed the master link with the supplied white grease, installed the X-rings then squeezed the link together using my aviation rivet squeezer. I you don't happen to have a rivet squeezer handy you could use a sturdy C clamp or something. They sell a tool for this purpose but it's about $60 usd or so. Next you need to "spread" the master link. The master link pins are hollow at the end so I used my rivet gun (fancy air chisel) with a punch attachment and to perform this task. Notice that I used a bucking bar behind the master link to support the link, otherwise you'll tear thinks up. After I installed the chain I noticed a little wobble to the sprocket. I verified this by using a dial indicator on the sprocket. There was approx .010" run out on the sprocket so I removed it and cleaned off some some dirt under the sprocket and on the threads of the bolts. After that, the run out was only about .002". Adjust the chain so there is about 1" of free play, tighten the axle nut and adjusters and it's all ready to go.