Sprockets

[r80rt]

Not the best pic, but you can see the difference in the bolt hole sizes. The 8.5 size fit my bike perfectly and the 10.5 was sloppy and loose.

 

[r80rt]

Will do, thanks. Have you tried x-ring chain? Wondering if it will be too wide and rub the crankcase.

I didn't use an O or X ring chain, but It looks like there is plenty of room for one. I believe Migolito used one with no problems.

 

[Senior CTptmcd]

13 tooth alterative, this is my JT SPROCKETS p/n JTR269-42. Running this stock 14t countershaft sprocket with the 42t rear sprocket and using the stock 108 link chain is the same as putting a 13t counter sprocket with stock 39t rear. chain life is better in this mode. sprocket hub center bore and 8mm bolt hole circle's are the same. sprocket mounting area material is thicker. the stock 8mm with 14mm hex lock nuts will ramp up on the machined edge on the new sprocket, i replaced them with 8mm with 13mm hex stainless nyloc's (blue nylon insert) to cure the problem. i did not want to damage the surface finish on the sprocket. there are other ways to get the minor problem cured, i chose this way , i had the nuts in my parts stock. also stock 108 link chain is used. i could now install a 13t or 15t counter sprocket as needed. as others here have mentioned go to gearingcommander.com and you can play with tire sizes and front and rear sprockets to see an approx. performance result of combinations. Happy wrenching riders.

 

[Senior CTptmcd]

in order to run a 15t counter shaft sprocket and my 42t rear sprocket a longer chain will be necessary. i have not done this swap.

 

[r80rt]

Nice.

 

[Arkansas rider]

13 tooth alterative, this is my JT SPROCKETS p/n JTR269-42. Running this stock 14t countershaft sprocket with the 42t rear sprocket and using the stock 108 link chain is the same as putting a 13t counter sprocket with stock 39t rear. chain life is better in this mode. sprocket hub center bore and 8mm bolt hole circle's are the same. sprocket mounting area material is thicker. the stock 8mm with 14mm hex lock nuts will ramp up on the machined edge on the new sprocket, i replaced them with 8mm with 13mm hex stainless nyloc's (blue nylon insert) to cure the problem. i did not want to damage the surface finish on the sprocket. there are other ways to get the minor problem cured, i chose this way , i had the nuts in my parts stock. also stock 108 link chain is used. i could now install a 13t or 15t counter sprocket as needed. as others here have mentioned go to gearingcommander.com and you can play with tire sizes and front and rear sprockets to see an approx. performance result of combinations. Happy wrenching riders.

Will the chain drop off shield fit the new jt sprocket?

 

[r80rt]

It is spot welded to the factory sprocket.

 

[Spydie]

It is spot welded to the factory sprocket.

I wonder if he meant the chain guard?

 

[Senior CTptmcd]

it looks like no, the added thickness of the new sprocket mounting stud area would move the drop off shield into the rear chain guard mount. i'm sure one could work around all the trouble spots but not worth the effort to me.

 

[mars rover]

Yes, it's the same sprocket sizes that came stock on the CT90's. The CT125 comes with a sprocket ratio of 2.79 and these sprockets have a ratio of 3.00. For me it's the perfect set up. If I were going to stay on pavement I'd keep the stock gearing and tires. Here is a chart to help with sprocket gearing. These bikes have a bout 1.2 horsepower more than the old ones, it's not a lot, but on a motor this size it's pretty big. With the lower gearing the extra power is noticeable.
View attachment 170

Thanks r80rt- this is just what I needed. I am interested in increasing top speed by about 5 miles per hour. I know that 4th gear is an overdrive gear with a ratio of .94 if I am not mistaken. How can I figure the top speed with different sprockets ? I am asking you because you seem to be very knowledgeable abou this stuff. Thanks in advance. mars

 

[Spydie]

Thanks r80rt- this is just what I needed. I am interested in increasing top speed by about 5 miles per hour. I know that 4th gear is an overdrive gear with a ratio of .94 if I am not mistaken. How can I figure the top speed with different sprockets ? I am asking you because you seem to be very knowledgeable abou this stuff. Thanks in advance. mars

Higher top speed has not been possible with this bike. One guy tried a 15 front sprocket, but the engine runs out of power so it can't go faster. Dropping from the stock 14t sprocket to a 13 tooth decreases top speed about 2 mph, except in a wind or up a hill, then you can gain about 2 mph over the 14t. It's all about power. At about 8 hp, you just can't extract more speed from it. You can get more power, but speed is limited by the low hp. The only solution is a big bore kit.

 

[m in sc]

rode mine yesterday, have a bit over 120 miles on it but had my tb cam & efie in for the last 60, and top speed has increased to 57 tapping 58 indicated with no sprocket changes on flat land. so yes, more HP is needed to overcome it for sure. the intake and exhaust are the real bottleneck but it is what it is. I'm good with that on this bike. IF they ever make a less restrictive replacement intake tube that will fit like an oem one from the airbox to TB i'll probably be on board with that. I wouldn't be surprised if KOSO had one in the works.

 

[r80rt]

When I had the stock sprockets my indicated top speed was 56 mph, I haven't tried to see what it is with the 15/45 sprockets yet.

 

[r80rt]

Thanks r80rt- this is just what I needed. I am interested in increasing top speed by about 5 miles per hour. I know that 4th gear is an overdrive gear with a ratio of .94 if I am not mistaken. How can I figure the top speed with different sprockets ? I am asking you because you seem to be very knowledgeable abou this stuff. Thanks in advance. mars

Sadly there just isn't enough horsepower here for a top speed increase, these bikes are slow. For speed, the stock gearing is probably as good as it gets.

 

[m in sc]

i agree. the stock ratio is about as good as it gets for all around for street riding. as a side note, i weigh in at 210 lbs. prior my top speed indicated was about 52-53 and struggled up hills way more. but its also still breaking it. they do tend to loosen up at around 200-300 miles , at least that's what i saw from the grom motors. .02

 

[Spydie]

i agree. the stock ratio is about as good as it gets for all around for street riding. as a side note, i weigh in at 210 lbs. prior my top speed indicated was about 52-53 and struggled up hills way more. but its also still breaking it. they do tend to loosen up at around 200-300 miles , at least that's what i saw from the grom motors. .02

I saw mine hit a plateau for loosening up at around 500 miles. It was noticeable. I can't get the 56-58 mph you guys are getting, and I weight 130 lbs. But I'm at 4400 feet altitude and it seems that the guys that are getting higher speeds are at a much lower altitude, so I think that's what makes a difference. It's also hard to find a no-wind day, and even when a road looks level, it usually has some grade to it so that makes a difference which direction you are going. If you are hitting 57-58, then turn around and go the other way and 99 times out of a hundred, you'll see the speed drop, then you have to average the two.

 

[AZ7000']

Ordered a 13 on Amazon for $12 or so, didn’t show in 2+ weeks and contacted the seller, they sent me a refund and it showed up the next day with a label that looked to be erased by a belt or something.

The more I read the more I think I’ll keep it the way it is.. keep posting so we can all learn from ya!

 

[Spydie]

Ordered a 13 on Amazon for $12 or so, didn’t show in 2+ weeks and contacted the seller, they sent me a refund and it showed up the next day with a label that looked to be erased by a belt or something.

The more I read the more I think I’ll keep it the way it is.. keep posting so we can all learn from ya!

I went to the 13 and loved the power increase (you can see it on my YouTube channel) but then I switched back to the 14 and the sluggish take-off and time to get to speed killed me, so I went back to the 13. I hate losing 2 mph on top end but the power increase is plus. I also hate the high RPMs. But the 14 is such a dog. I have ordered a 41t rear so that should give me the best of both worlds. The stock gearing is 2.79, the 13t front gives 3.00, but the 14t front and 41t rear will give 2.93, or I can put the 13 on the front and get lower off-road gear of 3.15.

 

[mars rover]

Thank you all for your knowledgeable replies. I have asked questions on other forums (not about the CT125) and waited days and weeks for a reply. This os a GREAT forum.
I guess that I will leave the sprockets alone and get a big bore kit later.

 

[Spydie]

Thank you all for your knowledgeable replies. I have asked questions on other forums (not about the CT125) and waited days and weeks for a reply. This os a GREAT forum.
I guess that I will leave the sprockets alone and get a big bore kit later.

This forum is not nearly as active as the Adventure Rider forum, but a lot of the same guys are on both.

Honda CT125/ Trail 125/ Hunter Cub

at the moment theyre less than 100 quid over 2 grand in thailand 86000 baht - shipping would be 6-700 quid hmrc told me that its 10% duty on that...

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