How to Replace Motorcycle Sprockets and Chain

Tools needed include drill with grinder head, chain breaking and riveting tool (blue box in the centre), torque wrench.

I decided to replace my F700GS chain, front and rear sprockets myself. The OEM endless chain gives 31,600 km service, which wears faster than my expected 40,000 km service. I often ride two-up with my wife, and this load factor might reduce the lifetime.

To have a certified mechanics replace the chain and the sprockets would cost about $190 (i.e., a 2-hour job). To do it myself I bought Motion Pro's Chain Breaker and Riveting Tool for $160 (in Canadian dollar; it should be much cheaper if bought in US, even with US dollar). Wheel-bearing grease costs $6, and ceramics grinder head $6, so the saving isn't much if I intend to do it once. The saving I want to make will be realized if I replace the chain myself at least twice; it's both tool and skill investment.

I read this useful website to learn about chain replacement without sprocket replacement, in addition to information from the instruction manual of the Tool.

Other tools needed are goggle, grease, torque wrench drive, wrenches of required sizes, sockets of required sizes, ceramics grinder head, drill, screw driver. A caliper is optional, but it is essential if complete agreement between measured rivets' flare width and the chain manufacturer's manual is required.

The numbered steps below are chronologically arranged and do not give detailed step-by-step instructions which are provided by the Tool instruction manual. These 14 steps are proven to have worked for my case. They give the major steps and are best followed in conjunction with the manuals of your motorcycle, chain manufacturer, and chain breaking and riveting tool you use. They suggest that motorcycle chain replacement and sprocket replacement is a complicated procedure and may be best performed by a certified mechanics if you aren't sure.

First step: Open the front sprocket cover using Torx wrench.

1. Open front sprocket cover and chain guard to help smooth the chain removal process later. They are usually held by screws.

Count the number of outer side plates of your chain. Use a Sharpie marker to mark the chain numbers. There are two chain side plate types in a chain: outer (O) and inner (I). To verify your count, repeat your first count and accept the number if it is repeated. For BMW F700GS, the number of outer side plates is 58. There are therefore 58 inner side plates. There are 2 x 58 = 116 riveted pins therefore in the chain.

Rear (left) and front (right) sprockets are now exposed. Chain is crooked due to kinks.

2. Use the grinder head to grind off one rivet of any pin connecting two side plates of the chain. Only one rivet needs to be ground off for breaking the chain. This step reduces mechanical stress to the chain tool's breaking tip when pushing the pin. Wear a goggle to protect your eyes from flying steel debris.

Grinding to remove the rivet of a pin helps reduce the breaking tip's mechanical stress.

I find the grinding step indispensible to ease pushing the ground pin out using the Tool as described in Step 3 below. In my opinion, since my original OEM chain pins are slender solid steel rods, it would be impossible to push out the pin if its rivet is not ground off; it will rupture the breaking tip of the Tool.

The chain breaking & riveting tool here is configured to push out the unriveted pin.

3. Use the Motion Pro's Chain Breaker and Riveting Tool to break the current chain. Please refer to its instruction manual for more detailed step-by-step instruction on how to use the Tool to break the chain. Basically, its breaking tip, when the Tool pieces are correctly assembled, is used to push out the unriveted pin so that the chain links are broken and can be removed.

The pushed pin is visible on the upper left edge of the vice body. The pin can be pushed only after its rivet is ground off.

4. Remove the chain by rolling it off the front and rear sprockets. Be careful not to have your fingers caught between the chain and a sprocket.

5. Put the broken chain and the new chain side by side on newspaper sheets. This is to make sure that the length of the new chain together with the master link is the same as the broken's. The new chain is almost certainly longer than the broken and therefore needs to be cut to have exactly the same length. If a cutting mistake results in a shorter chain, a new chain needs to be purchased.

Repeat counting the number of outer side plates of the broken chain. The number should confirm the previous number from Step 1. 

There are two chain side plate types in a chain: outer (O) and inner (I). Their sequence in my new chain is I-O-I-O-I-O-I-...-O-I. (To form a chain, the first (I) and the last (O) side plate have to be different so that they can be linked together.) Because the master link is of type O and is initially separate from the new chain, the new chain needs to be cut to give exactly (i) the sequence I-O-I-O-...-O-I and (ii) one O-type side plate fewer than the number of O-type side plates of the broken (old) chain. The master link is then used to connect the resulting sequence I-O-I-O-...-O-I from the cutting in order to form a chain.

For example, my new chain has 59 outer side plates and 1 O-type master link. Because the broken chain has 58 outer side plates, I have to remove 2 outer side plates from the new chain to give me 57 outer side plates. The master link then makes the total number of outer side plates 58.

Note that both words "link" and "side plate" refer to the same object. The total number of side plates is therefore equal to the number of links in a chain. The number of pins is also equal to the number of links.

6. Grind off the rivet of the correct pin so that the cut new chain has (i) I-O-I-O-...-O-I sequence and (ii) one O-type link plate fewer than the number of O-type link plates of the old chain. Use the Tool to push the unriveted pin out, and thus cut the new chain into two parts. Discard the shorter part (and make a nice key chain out of it.)

7. Remove the current front sprocket from its shaft. It is usually held by a bolt which can be loosened using a torque wrench. Clean the area around the shaft to prepare for the new front sprocket installation. Install the new front sprocket by applying the correct amount of torque as specified by your motorcycle manual -if available- to tighten it using torque wrench.

Installing the new front sprocket. Washing the front sprocket area with water removes accumulating oil and dirt cakes. It's important to remove the water using oil penetrant so that water is not present in the crevices and there will be low corrosion risk.

Old (left) and new (right) front sprockets. The old sprocket's cogs are worn out.

8. Remove the rear tire (which includes the wheel, i.e., rim, that the rear sprocket is bolted to) as per your motorcycle manual. Make sure to properly disconnect speed sensor cable and to not scratch the brake disc by resting the tire flat on wooden bars.

Rear tire unit has to be removed so that rear sprocket can be accessed and replaced. Follow your motorcycle's manual on how to remove the rear tire unit.

Place the rear tire unit on top of wooden bars to prevent the brake disc from getting scratched.

9. Remove the rear sprocket from the wheel. Install the new rear sprocket by applying the correct amount of torque as per manual to tighten it using torque wrench.

New (left) and old (right) rear sprockets. 

10. Install the rear tire with the new rear sprocket back as per manual. At this stage do not tighten the rear axle bolt yet. You will need to push the rear wheel forward when connecting the cut new chain using a master link.

The rear wheel installation takes a lot of time for me due to aligning the brake disc, rear axle, and spacers. It is helpful to have another person help insert the rear axle. My son helped me in this step. We had a great father-son conversation (shop talk) while working together. Unforgettable!

11. Wrap the still-unconnected new chain around the new sprockets. Ensure that the upper part of the wrapped chain between the front and rear sprockets is as tight as the old one.

The chain breaking and riveting tool is now configured to push the master link's side plate.

12. Connect the new chain using the master link. This step also requires assembly of the master link's parts (o-ring seals, side plates) correctly, as per chain manufacturer's manual, when connecting the new chain. Use the Tool to press the master link's side plate. The Tool piece assembly for this step is different from the chain breaking assembly, as per the Tool manual.

It is best to press the side plate in several slow steps. That way you can inspect and slowly increase the amount of protrusions (flares) of the pins.

13. Assemble the Tool pieces, as per Tool manual, so that the Tool is now used to create rivets from the two hollow pins of the master link. The plugged end of each pin should be at the inside (facing away from you) of the chain. The open end which will be flared by the Tool to form a rivet, is at the outside (facing toward you) of the chain.

In my case the master link's pins have a pre-installed side plate, so I don't have to worry about identifying the plugged and the open ends of the pins.

This step is critical since the amount of flares determines the mechanical integrity of the chain. A flushed flare with the side plate may crack the pin. Not enough flare will not hold the side plate solidly in place. As an important option: use a caliper to correctly determine the amount of flare by taking the difference between the flared pin's diameter and the unflared pin's diameter.

Once the push bolt of the riveting tool feels tight, I apply 3/4 of a turn to produce each rivet. Repeat this step for the second pin. I press the riveting tool twice for each pin to produce the rivets on the two pins' heads.

This is the verbatim safety warning from the Motion Pro's Chain Breaking and Riveting Tool's manual:

* It is very important that chain master links be clipped or riveted properly. Improper installation can lead to great bodily harm or death. If you are unfamiliar or uncomfortable with this process, please have your work supervised by a qualified technician or bring your vehicle to a qualified facility for repair.

Quality of the rivets of the master link by following the steps outlined in this blog.

14. Turn the rear wheel to make sure that the chain runs through the sprockets without intermittency. Adjust the chain sag as per your motorcycle manual. Install the front sprocket cover and the chain guard.