TT250 rear sprocket, etc fun

mtiberio · 09-25-2016, 05:22 PM

So I'm experimenting on gearing for my TT250. Stock 50 tooth rear is too short, and I'd like to maximize highway speed with minimal revs. I purchased a JTR269-49 and a JTR269-47, I also purchased from PBI in Aluminum, a 3041-46 and a 3041-48. Together, I now have from 46 through 50 to choose from. I first tried the 47. Great reduction in revs at top speed, but I felt like top speed was compromised. Now trying a 48, and haven't had a chance to do any extended top end runs. Will report later...

A couple of things. Given the offset in the stock sprocket, and the fact that all my alternative sprockets are flat. I was thinking, why not stack two sprockets with appropriate spacers, to give you multiple choices in rear gearing with nothing more than a axle loosen and chain adjust? Leave both sprockets mounted, and just move the chain side to side. Either sprocket would be no more off centerline that my current flat ones are relative to the stock offset. Just a thought. Currently I have run the 50, 48 and 47, and haven't shortened my chain. Once I decide on gearing I'll get a quality o-ring chain of the right length. Still I might have a dual rear sprocket setup in the future...

Lastly, not chain or gearing related, but I noticed that one of the rear brake hoses holder clamps was secured by the caliper retention bolt. Since I haven't figure out how to remove the rear wheel without pulling the caliper from the caliper hanger, I wanted to remove the clamp to simplify bolt tightening. When I did this, the bolt stuck through, and rubbed the disc at its high spot. Solved with a washer, but a word to the wise...

culcune · 09-25-2016, 07:44 PM

Interesting experiment with trying all the different sprockets. Not sure about mounting two side by side, and I am sure someone with more knowledge on why that can or cannot work will chime in.

I believe for street duty, you probably want a 17 countersprocket. Not sure if you already changed this and mentioned it in a different thread, so if you have, sorry for repeating it, but if not, you should play around with front sprockets, too, to see if you can find a 'sweet' setup.

kohburn · 09-25-2016, 07:56 PM

i tried the 47 and ended up at 43. with the 43 it sits right at peak torque at highway cruise speed of roughly 65. when following other cars/trucks or with a tail wind i've hit 70 so I suspect a few mods to open up the top end a little would take it there also.

43 is too long for much technical off road i think, but would be fine for fire roads and maintained trails.

i've done the stacked sprocket. i flipped the stock 50 to the inside and put the smaller one on the outside and it works fine. from what i can tell the chain is actually better aligned with a flat sprocket than with the offset.

darmst6829 · 09-25-2016, 08:53 PM

43 tooth works great for me. I have done some heavy duty trail rides without to much trouble.

mtiberio · 09-25-2016, 11:02 PM

looking forward to try the 46...

'16 TT250 · 09-26-2016, 02:07 AM

You really want the chain to be straight which can't be done with two sprockets to swap back & forth between. That said, it may not be a huge deal on a low power bike, but it' not ideal for it to be at an angle. Also, an o-ring chain has more drag so you'll lose some speed/efficiency over a non-oring chain. If you want low drag and low maintenance get an automatic luber. I don't mind chain lubing at all; disable the side stand switch (if it has one) or put it on a stand, run the engine in gear and spray.

09-25-2016, 05:22 PM	#1
mtiberio Join Date: Jun 2016 Location: Arlington, VA Posts: 258	TT250 rear sprocket, etc fun So I'm experimenting on gearing for my TT250. Stock 50 tooth rear is too short, and I'd like to maximize highway speed with minimal revs. I purchased a JTR269-49 and a JTR269-47, I also purchased from PBI in Aluminum, a 3041-46 and a 3041-48. Together, I now have from 46 through 50 to choose from. I first tried the 47. Great reduction in revs at top speed, but I felt like top speed was compromised. Now trying a 48, and haven't had a chance to do any extended top end runs. Will report later... A couple of things. Given the offset in the stock sprocket, and the fact that all my alternative sprockets are flat. I was thinking, why not stack two sprockets with appropriate spacers, to give you multiple choices in rear gearing with nothing more than a axle loosen and chain adjust? Leave both sprockets mounted, and just move the chain side to side. Either sprocket would be no more off centerline that my current flat ones are relative to the stock offset. Just a thought. Currently I have run the 50, 48 and 47, and haven't shortened my chain. Once I decide on gearing I'll get a quality o-ring chain of the right length. Still I might have a dual rear sprocket setup in the future... Lastly, not chain or gearing related, but I noticed that one of the rear brake hoses holder clamps was secured by the caliper retention bolt. Since I haven't figure out how to remove the rear wheel without pulling the caliper from the caliper hanger, I wanted to remove the clamp to simplify bolt tightening. When I did this, the bolt stuck through, and rubbed the disc at its high spot. Solved with a washer, but a word to the wise...
	0

09-25-2016, 07:44 PM	#2
culcune Join Date: May 2006 Location: Yuma, Arizona Posts: 9,035	Interesting experiment with trying all the different sprockets. Not sure about mounting two side by side, and I am sure someone with more knowledge on why that can or cannot work will chime in. I believe for street duty, you probably want a 17 countersprocket. Not sure if you already changed this and mentioned it in a different thread, so if you have, sorry for repeating it, but if not, you should play around with front sprockets, too, to see if you can find a 'sweet' setup. __________________ "They say that life's a carousel, spinning fast you got to ride it well..." TGB Delivery Scooter 150 TMEC 200 Enduro--carcass is sadly rotting in the backyard
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09-25-2016, 07:56 PM	#3
kohburn Join Date: Dec 2015 Location: Coastal NC Posts: 537	i tried the 47 and ended up at 43. with the 43 it sits right at peak torque at highway cruise speed of roughly 65. when following other cars/trucks or with a tail wind i've hit 70 so I suspect a few mods to open up the top end a little would take it there also. 43 is too long for much technical off road i think, but would be fine for fire roads and maintained trails. i've done the stacked sprocket. i flipped the stock 50 to the inside and put the smaller one on the outside and it works fine. from what i can tell the chain is actually better aligned with a flat sprocket than with the offset. __________________ -whatever you do, just be awesome. - 2008 Kawasaki Versys - 2016 CSC TT250
	1

09-25-2016, 08:53 PM	#4
darmst6829 Join Date: May 2016 Location: Redmond WA Posts: 42	43 tooth works great for me. I have done some heavy duty trail rides without to much trouble.
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09-25-2016, 11:02 PM	#5
mtiberio Join Date: Jun 2016 Location: Arlington, VA Posts: 258	looking forward to try the 46...
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09-26-2016, 02:07 AM	#6
'16 TT250 Join Date: May 2016 Location: Hacienda Heights, Ca Posts: 281	You really want the chain to be straight which can't be done with two sprockets to swap back & forth between. That said, it may not be a huge deal on a low power bike, but it' not ideal for it to be at an angle. Also, an o-ring chain has more drag so you'll lose some speed/efficiency over a non-oring chain. If you want low drag and low maintenance get an automatic luber. I don't mind chain lubing at all; disable the side stand switch (if it has one) or put it on a stand, run the engine in gear and spray.
	0