Changing Sprockets

Bike mechanical/electrical modifications and general wrenching advice.
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Champ87
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Changing Sprockets

Post by Champ87 » Thu Mar 14, 2019 2:44 am


A few months back I bought front and rear sprockets to change the gearing on my SE. My aim is to bring rpm down for a more comfortable cruise and maybe increase tank range. It might hurt acceleration but that’s not always the case. With plenty of available power and ECU flashed by vcyclenut, I think the bike has enough guts for any acceleration loss to be minimal and only be noticeable under timed conditions (if at all).

My target is to bring the rpm down to 5,000 rpm at 85 mph – the maximum that cruise control will hold. That's a drop of around 500 rpm. For the front I went +1 with a 19T Vortex sprocket from vcyclenut. At the rear I’m going 2 teeth less with a 42T steel sprocket from SuperSproxUSA.

I’d hoped to change the front sprocket and try it out before winter but, when I went to make the change, I found out that changing sprockets on this bike is not the quick swap that I’m used to. There is a guard around the engine sprocket. To remove that requires the clutch slave cylinder to be removed which, in turn, requires the water pump cover to be loosened which, in turn, requires the coolant to be drained…… I didn’t have enough time for all that, so I left it alone and put the sprocket cover back on. I revisited the task last weekend.

If the description below looks long that’s because it is - the whole process took about 2 hours (really did!) and I started with the left fairing already removed for another project. I haven’t had a chance to see what it feels like to ride with the new front sprocket but I’ll share the experience of fitting it. When I get around to changing the rear I’ll provide a write up for that too. Meanwhile, here’s Champ87’s suggested sequence for front sprocket removal:
  • Remove the engine sprocket cover
  • Flatten out the lock washer and loosen the engine sprocket nut. I put the bike on the sidestand, in gear with a tie to hold the front brake on. I stomped on the rear brake while leaning across the bike to use a big breaker bar. No surprise, it took some serious grunt to break it loose, but break loose it did. A one man job but it would help to have a friend available to hold the bike and stomp on rear brake
  • Drain coolant – there is a drain bolt on the water pump cover. Not much coolant will come out until you release the radiator cap. I collected 1.8L. Leave the bike on the sidestand. You’ll get slightly more out that way – less to spill on the floor when you remove the water pump cover
  • Put the bike on the center stand/paddock stand and loosen the chain to maximum slack
  • Remove the shift lever
  • Loosen water pump cover. You can leave the hoses attached – the cover just needs to be moved to get to a bolt
  • Remove clutch slave cylinder. The service manual says pull the clutch lever while holding the piston then tie the lever back to bar to prevent piston from coming out. I did that but still felt nervous about the piston creeping out, so I also used a clamp to hold the piston in place
  • Remove the bolts holding the engine sprocket chain guard. Remove the clutch slave cylinder holder and lift the chain guard away
  • Replace the sprocket. Refit the lock washer and nut. Torque to correct setting and bend the lock washer tab into place
  • Replace the chain guard and slave cylinder holder. Service manual says to use thread locking agent on the holding bolts. Torque the bolts
  • Refit clutch slave cylinder. There is a gasket – the service manual says to fit a new one, but it looks like it would be reusable. I had a new one to hand so I replaced anyway. Use thread locking agent and torque the bolts
  • Refit the water pump cover. There is an O-Ring in a groove in the water pump cover. I bought a spare just in case. New O-Ring works better on the bike than in the packet, so I fitted new. Check that locating dowels are still in place before positioning the cover. Torque the bolts
  • Refit the shift lever using the indent mark to align the lever on the shaft
  • Replace the engine sprocket cover
  • Adjust chain
  • Refill coolant. Run engine up to normal operating temp to purge air from cooling system. Allow to cool down then check coolant level
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JonTheChron
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Re: Changing Sprockets

Post by JonTheChron » Thu Mar 14, 2019 6:14 pm


Thanks for the info, I have the same 19/42 setup as you but I haven't tried it on the streets yet. This definitely gives me a good impression
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Re: Changing Sprockets

Post by Champ87 » Mon Mar 18, 2019 7:14 pm


My next step is rear sprocket change, so I looked at the service manual to see what’s involved. Like the front sprocket, changing the rear is a lot more work than I’d expected. On my previous bike, Triumph Sprint, the single-sided swingarm made rear sprocket change easy. I didn’t even need to remove the wheel: simply removed the sprocket holding nuts and replaced the sprocket.

The same cannot be done with the H2 SX. The sprocket holding nuts are on the back side of the carrier so the whole coupling assembly must be removed. To do that, the wheel must be removed which requires muffler removal. I don’t know why Kawasaki didn’t design it with the nuts facing out. The way they’ve done it maybe looks neater, but it makes a lot of work. Replacing sprockets is something most of us do at some time so I’ll follow with details when I get time to change the rear sprocket.

Single-sided swingarm allowed Sprint ST sprocket to be changed without removing wheel
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Re: Changing Sprockets

Post by cOoTeR » Mon Mar 18, 2019 11:04 pm


Would the method below work on our bikes? Seems like it could save time. I haven't really looked into it yet. Check out post #4. I think a ratcheting wrench might work as well.

https://www.ninjah2.org/forum/ninja-h2- ... pics/23385

EDIT: I'm trying to post a screen shot from the post but it doesn't seem to be working.
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Screen shot from post #4.
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Re: Changing Sprockets

Post by Raddy47 » Tue Mar 19, 2019 12:02 am


Help me understand.. I’m coming from a 600cc gsxr that had 520 race gearing setup. Great for acceleration but was a nightmare at hwy speeds cruising. Lots of vibrations at hwy speed. My se+ is a dream 30-80 cruising. I start to feel that higher vibration like the bike is on the fence of let’s go or back it down 85-95. Everything else is cloud like to me. Super smooth. So if you aren’t trying to get better acceleration or a better top end speed. I think changing up the gears is a waste. If you do 85 everywhere I don’t know what to tell ya. Seems like a headache when you could just slow down 5 or speed the hell up. Just my opinion. Do what suits your riding style needs best though.
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Re: Changing Sprockets

Post by Champ87 » Tue Mar 19, 2019 12:37 am


cOoTeR wrote:
Mon Mar 18, 2019 11:04 pm
Would the method below work on our bikes? Seems like it could save time. I haven't really looked into it yet. Check out post #4. I think a ratcheting wrench might work as well.
Thanks for that

Yes, I was wondering if I could get a wrench behind the carrier. I do have a set of ratcheting wrenches so I will investigate. If it works then my only reservation would be that I won't be able to torques the bolts. Stuff like that bothers me. It shouldn't because I spent enough years without worrying about torque settings if I needed to change a sprocket quickly between races.
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Re: Changing Sprockets

Post by Champ87 » Tue Mar 19, 2019 1:19 am


Raddy47 wrote:
Tue Mar 19, 2019 12:02 am
Help me understand.....
A look into the mind of Champ87........ :wtf:

If speeding up or slowing down was what I wanted to do then I'd.......simply speed up or slow down. That's fine for general riding but, on a road trip, that may not be the best option. On my last road trip (not this bike) I covered 6,500+ miles in two weeks. That involved a lot of mileage between various place I visited. Using cruise control really helps comfort. I'd like to be able to use it at any speed up to the maximum it can be set - 85 mph. I agree that the bike "is a dream 30-80 cruising" but at 85 mph it feels a little busy to me so it makes sense (to me) to change the gearing to suit what I want. That will give me a more enjoyable ride and a lot less fatigue over a long day.

Not everyone will agree with my approach but there are plenty on this forum who will change sprockets themselves, if only to replace worn originals. Sharing the information may help some and definitely won't do any harm to those who don't care.
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Re: Changing Sprockets

Post by Snakes709 » Tue Mar 19, 2019 1:52 am


Think you over thinking the rear sprocket. Here is a video of EC’s hyper drive on the H2. Same steps for changing sprockets

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Re: Changing Sprockets

Post by Champ87 » Tue Mar 19, 2019 2:15 am


Snakes709 wrote:
Tue Mar 19, 2019 1:52 am
Think you over thinking the rear sprocket. Here is a video of EC’s hyper drive on the H2. Same steps for changing sprockets
No, for H2 SX the steps are different because our bikes have a different axle arrangement.
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Re: Changing Sprockets

Post by Snakes709 » Tue Mar 19, 2019 2:25 am


Champ87 wrote:
Tue Mar 19, 2019 2:15 am
Snakes709 wrote:
Tue Mar 19, 2019 1:52 am
Think you over thinking the rear sprocket. Here is a video of EC’s hyper drive on the H2. Same steps for changing sprockets
No, for H2 SX the steps are different because our bikes have a different axle arrangement.
The hub assembly should come off the same way thought, shouldnt it?
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