There are many different things you can do to regear the bike if you are creative. The stock setup is 30 tooth front and 70 tooth rear. The belt is 144 teeth, 14mm pitch, and around 2cm wide (needs confirmation). Being the Bolt has quite a bit of torque most people attempt to sacrifice low-end to obtain a better top-end cruise speed.
Things to consider. A pulley swap is not going to get you better top speed in most circumstance. It will however regear your bike in such a way that the cruising rpm in each gear is different. Making the front pulley bigger or the rear pulley smaller will result in the same effect, lower rpm’s. Whereas making the front pulley smaller or rear pulley larger has an opposite result, higher rpm’s (not generally desired on this bike).
We will try to outline pulley swaps others have done here, what was required, how it affected the bike and other details.
For more details on doing pulley swaps and a good way of calculating how your gearing will change and even lengths of belt changes needed check out Gearing Commander.
Stryker front pulley (31T) #
Part Number: 27D-17651-00-00
This is by far the most common pulley swap that people do on the bike. The 31 tooth front pulley from a Yamaha Stryker fits on the Yamaha Bolt. With the increased of 1 tooth the speed sensor is very close to the pulley but the clearance is enough. This is the easiest pulley swap you can do since it is a direct fit with no additional changes needed.
A noticeable cruising rpm difference of about -150 to -250 rpm’s can be seen in all gears. This means that there is a sacrifice of the low-end. Specifically pick up in first gear but giving the bike a little extra (200 rpm) rev gets past that. Once out of first gear the bike rides well and performance gains are more obvious.
Road Warrior front pulley (32T) #
Part Number: 5PX-17651-00-00
The Yamaha Star Road Warrior pulley is not quite as simple but should not be overtly difficult either. It is 32 tooth. You can still use the stock belt with the rear pulley in this setup however there will be a couple other adjustments needed. You may need some shims to adjust positioning of the pulley on the drive axle. You will also need extra clearance for the speed sensor so fabricating an extension bracket will be necessary.
Cruising rpm difference will be about -400 to -600 most likely.
Raider rear pulley (66T) #
Part Number: 5C7-25466-01-00
The Yamaha Raider had a 66 tooth rear pulley and seems like it might be one of the only Yamaha models that had a 66 tooth rear. Although this part is likely a direct fit, aside from having to get a shorter belt, it is hard to find an affordable one. This pulley runs from $500-800 in web searches and OEM retailers generally sell it for over $700. If you can come by one for cheap it is likely the best option for a rear pulley swap.
Dyna rear pulley (66T) #
A Dyna rear pulley is 66 tooth. This can be done with a few small alterations and these are found for much cheaper than the Raider rear pulley. The pulley has to be mounted backwards due to the concave shape. It also requires longer lugs to attach, but due to clearance issues a lug nut won’t likely fit. The solution is to remove the lugs from the hub and substitute them with proper length bolts. Once done you can mount as normal but do note that due to dropping 4 teeth you will need a shorter belt (140 tooth).
Shorter belts #
It seems that most of the belt driven production motorcycles share similar or at least very close specs on belts. The Bolt has a 144 tooth / 14mm pitch / ~2mm width belt. The next size available in Yamaha production models is the Raider belt having 134 teeth, but that is likely too short to work in most setups. A 140 tooth belt is likely the best solution.
Harley belt #
There are Harley belts available that are very close in size but offer a shorter length when dropping teeth. Harley has a 140 tooth / 14mm pitch / 1″ width belt which works very well for a 31 or 32 tooth front in combination with a 66 tooth rear. Prices for this belt are around $150.
Speedometer accuracy? #
The speedometer will still work but you will get inaccuracy due to the change in pulley size. A pulley change is essentially like changing tire size. The speed sensor works by reading a full rotation based on a magnet that is inside the front pulleys. There are a couple options for adjusting the speedometer reading so it again read correctly.