[Alain Ternet]

I would like to change my 49 tooth rear sprocket (for a 47 or 45, I can't decide) but I wonder if I can just change the rear sprocket without changing the front one and without changing the O-ring chain? I know it's best to change everything at once but the current sprockets and chain were changed by the last owner and they were used for 620 miles only. It is too late to change the rear sprocket ?

 

[admiral]

It's perfectly fine to change only one sprocket if you want to, especially with the low use/mileage you mention. The only issue you may have is if you change to a smaller sprocket your chain may be too long. Probably not too long if you change from 49 to 47 but you will most likely need to shorten (remove some chain links) if you change to 45. You won't know for sure until you change the sprocket and "test fit" it to make sure you have the proper length chain.

 

[SpeedyTide]

Not a have to do, if chain in good shape, but a good time to upgrade to an O or X-ring.

EDIT: Oops....you mentioned you already have an O-ring.

 

[PlacerLode]

Simply change your front sprocket to a 15 it’s cheap fast and you won’t have to cut your chain
One front tooth equates to aprx 3 1/2 rear teeth and you can get front sprockets from 11 to 16 tooth 14 being stock

I run a 16 tooth front from PBI sprockets I can still use the stock chain length and can change to any other front sprocket as a trail side swap

 

[GCFishguy]

I run a 16 tooth front from PBI sprockets I can still use the stock chain length and can change to any other front sprocket as a trail side swap

Okay, if nobody else is going to ask, I guess I have to.....

 

[Fred]

One might wish to decide how much of a gearing change one wishes to achieve. The change in ratios discussed so far range from a bit over 4% to a bit ovr 14%. Be aware that while a 16 tooth will have engine operating at about 14% less rpm for any given over the ground speed it conversely will not make the bike go 14% faster. Not sure if even the 4% gearing change of a 47 vs 49 tooth rear sprocket will permit a 4% increase in top speed. Wind resistance, or drag, increases with the velocity squared and unfortunately the TW power output does not even increase linearly approaching the redline.

 

[Alain Ternet]

Thank you all for suggestions!
About the choice of sprocket (47T or 45T), I read a lot of different points of view. My goal is to ride 95% on the road without hills (city) and I weigh 220 pounds. I would like to be able to ride at 60 mph without the rpm being too high... Is it realistic ?

 

[jamesroyster13]

Thank you all for suggestions!
About the choice of sprocket (47T or 45T), I read a lot of different points of view. My goal is to ride 95% on the road without hills (city) and I weigh 220 pounds. I would like to be able to ride at 60 mph without the rpm being too high... Is it realistic ?

Im sorta the same, I went with a 47 but wish id went 45 , jusayun

 

[Leisure Time Larry]

Alain, you already have a 47 tooth installed! I can tell from your picture. It is a JT Sprocket. The model number is stamped on it: JTR1842-47. JT is the manufacturer. R=Rear, and that 47 means it's a 47 tooth version of their model 1842. The 49 on there under the logo denotes that it is made from C49 High Carbon Steel. You better count 'em up!

Btw, for the record, none of the options, including the stock 50 tooth, would make your engine rpms "too high". Stop worrying. Just ride it! Put some miles on, or KMs since yoor a canuck, eh? After a few thousand, re-evaluate, but until then get you some smiles! As a noob, invest the money in good riding gear or a motorcycle safety course when the thaw comes. You won't regret it. Best-

 

[Rudolf]

I changed to a 47 and still run stock chain.

 

[elime]

Get a cheap tachometer and see how fast your engine is going. It may sound a lot faster than it really is going.

 

[SpeedyTide]

Alain, you already have a 47 tooth installed! I can tell from your picture. It is a JT Sprocket. The model number is stamped on it: JTR1842-47. JT is the manufacturer. R=Rear, and that 47 means it's a 47 tooth version of their model 1842. The 49 on there under the logo denotes that it is made from C49 High Carbon Steel. You better count 'em up!

Btw, for the record, none of the options, including the stock 50 tooth, would make your engine rpms "too high". Stop worrying. Just ride it! Put some miles on, or KMs since yoor a canuck, eh? After a few thousand, re-evaluate, but until then get you some smiles! As a noob, invest the money in good riding gear or a motorcycle safety course when the thaw comes. You won't regret it. Best-

Man, you must have a nice hi-res computer/laptop screen, or a large screen, and/or good eyesight!!

I do run my zoom around 80% on my 15.5" screen, but once I zoomed in....I could see it a bit better, just the clarity wasn't the best.

 

[PlacerLode]

15 tooth front equates to 46.5 rear
I think TW's should come with 15 tooth fronts it's the sweet spot for my style of riding which is fairly open 2 track desert

 

[Alain Ternet]

Alain, you already have a 47 tooth installed! I can tell from your picture. It is a JT Sprocket. The model number is stamped on it: JTR1842-47. JT is the manufacturer. R=Rear, and that 47 means it's a 47 tooth version of their model 1842. The 49 on there under the logo denotes that it is made from C49 High Carbon Steel.

Wow, you have a great sense of observation! I just counted and indeed, I have a 47 tooth sprocket. The guy who sold me the bike this fall told me he had changed the rear sprocket for a 49 and it was written 49 on it, that seemed logical to me! Thank you, I would have looked really stupid to change my 47 for another 47!

 

[Hazcat]

I would like to change my 49 tooth rear sprocket (for a 47 or 45, I can't decide) but I wonder if I can just change the rear sprocket without changing the front one and without changing the O-ring chain? I know it's best to change everything at once but the current sprockets and chain were changed by the last owner and they were used for 620 miles only. It is too late to change the rear sprocket ?

View attachment 233394

Here's a link to a calculator that will help you figure it all out Gearing Commander - Motorcycle Speed and Drive Train Calculator v7

 

[Dark Sol]

Nah dude, you thought you had a 49 so buying another 47 would have made a difference. A huge difference!

Placebo affect, ya know.

Seriously though stick with your 14/47, ride and enjoy. 45 or taller gearing isn't worth it and probably does the engine more harm than good despite allowing it to run a little slower. My bike bogged down big time especially 5th gear with 14/44 and 14/45. 14/47 was by far my favorite gearing for the 99% street riding I did. Also note I was only 130 pounds back when I had my TW, the tall gearing still totally sucked.

 

[Adam-n-nevada]

I've zoomed around on my first TW for thousands of miles at speeds greater than 65mph - with the rpms zinging over 9000rpms. I ran stock 14/50 then switched to 14/54 around 8000 miles. I had over 22,000 trouble free miles.

These little engines are durable and can take the beating. Although, I changed the oil nearly every 2-300 miles with that bike.

 

[JustPassinThru]

Simply change your front sprocket to a 15 it’s cheap fast and you won’t have to cut your chain
One front tooth equates to aprx 3 1/2 rear teeth and you can get front sprockets from 11 to 16 tooth 14 being stock

I run a 16 tooth front from PBI sprockets I can still use the stock chain length and can change to any other front sprocket as a trail side swap

That's exactly what I did. Changed the front sprocket, 14t, to a 15t. Subtle differences, but worthwhile, for a machine that sees 75-percent street use.

I didn't have to do anything to the chain.

I don't have an O-ring chain - because the dealer didn't have one in stock and couldn't find one with his parts sources. So I just said, fuggum, and got an allegedly-better-quality non-O-ring chain. Kept the sprockets.

Knowing that the chain and sprockets would wear much faster. Fine...the chain was cheap, and changing it once a year was cheap insurance, anyway. Made it easier - after the nuisance of opening the crankcase to get at the front sprocket, I could just use the un-clipped master link, to roll the new chain around the front, and then pull it back, break the new chain to length, and fasten it. Easy-peasy. Do it once a year; figure replacing sprockets every three years...done.

 

[WECSOG]

Thank you all for suggestions!
About the choice of sprocket (47T or 45T), I read a lot of different points of view. My goal is to ride 95% on the road without hills (city) and I weigh 220 pounds. I would like to be able to ride at 60 mph without the rpm being too high... Is it realistic ?

The rpm is not too high at 60 mph, even with factory gearing. Losing several teeth on the rear sprocket is actually harder on the engine because you are trying to get the same power at a lower rpm, which lugs the engine and is harder on the bottom end. I actually had to spend more time in a lower gear to compensate.