So after reading this thread I am guessing that a good city/highway mix with little to no hills would be 18/32? I will be doing about 20 miles a day highway and 10 city one way. Sorry for the broad question first bike.
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changing sprockets
- Thread starter bradshaw106
- Start date
18/32 is exactly the same numerical ratio as 17/30 - your choice. Either way, it's fairly high gearing, even for relatively flat terrain. Depends somewhat on what your rear wheel diameter is, 16 or 18 inches. I'm not sure you would be satisfied if you have an 18 inch rear. I 've got 17/31 now with 18 inch rear wheel and am considering going back to stock 34 rear, even with flat terrain around here.
Aldo, love your bike! I'm grinning thinking how long it'll be before you change back to 17/31 from stock gearing.......
It's an easy mod to do and to be able to see the change immediately....easily reversible except when you have to remove a couple of links in your drive train.
Some other stuff I want to do before changing a sprocket - need new exhaust system. Anyway, playing a bit with pamcopete's excellent rev chart program, it looks like changing from a 31 to a 34 rear would raise my current rpm about 300 at 50mph and 360 at 60 mph - that's my usual cruising speed range on my 650 - still a bit lower rpm's than what they'd be with a 16 inch rear wheel. I try to keep my carbs synched real closely to minimize vibration, so I don't expect that another 300-360 rpm would change how it feels now very much. Like you say, easy to do and undo if it doesn't work out.
I will go from 17/34 (stock) to 17/31. Someone said in this thread that 17/30 was equal to 18/32, but with a 17 instead of an 18 it would be easier on lower gears in the city. I'm going 31 because I like to drive more active or with a passenger sometimes .
But I assume it's all comes down to a vere subjective combination of personality, load, bike and area....
I read somewhere that when going from 34 to 32, you don't have to shorten the chain. Does anyone know if that goes for 34 to 31 as well? I would prefer not to shorten it, if I would like to go back to 34 later. Or would it be okej to use two chain locks? I have a 530 chain, 104 links i recall.
M
XS 650 -75B
M
XS 650 -75B
Simple. You won't have to shorten it if you have enough adjustment left. If you run out of adjustment then you have to shorten the chain. I went from stock 34 to 32 with no prob. 31 might be close to pushing it, but I doubt it. Only way to find out is to try it. Not much work.
Yes, I understand the trial and error method. 
When you adjusted the chain, did you end up in the middle or at the end?
The reason i asked was that I wanted to know before ordering from abroad. Would prefer not to shorten it, since changing back could mean that I would have to use two chain locks. And if 32 doesn't make such a big difference compared to 31, I could go for that.
I just preferred to know my options before paying, since I can't return it.
M
When you adjusted the chain, did you end up in the middle or at the end?
The reason i asked was that I wanted to know before ordering from abroad. Would prefer not to shorten it, since changing back could mean that I would have to use two chain locks. And if 32 doesn't make such a big difference compared to 31, I could go for that.
I just preferred to know my options before paying, since I can't return it.
M
I can say that the 17/30 combo will require 2 links to be removed but the 18/32 combo does not, and they are essentialy the same end ratio.
Some remove the shift shaft guard when running the 18 front sprocket and some don't.
I'm running 2 bikes now with the 18/32 combo and if I had a third bike it would be running it also. For me, it's perfect for the hills, hollows and the highway.
Some remove the shift shaft guard when running the 18 front sprocket and some don't.
I'm running 2 bikes now with the 18/32 combo and if I had a third bike it would be running it also. For me, it's perfect for the hills, hollows and the highway.
Just reading through everyone's posts about sizes and their ride feel... It seems like you all are riding with little to no freeway time. I have a question though, as I hit the freeway for about 10-15 miles to get into town were I ride with friends. I live in the cuts...
I ride in the Santa Cruz Mountains, and up and down the California Coast. I also ride in the foothills around my area. I love the feel of a responsive throttle around the backroads, but I want to cruise with my friends at 80mph along the highway when we go on longer rides... Then there is the fact that to get to my friends I always have bout 10 extra freeway miles to and from home.
I don't take passengers on this bike. Not to mention I haven't even run this bike yet. This is also my first XS650. I've got a '79 special, it has 17/34 gearing. Anyone have suggestions of what I should do about the ratio? I want to cruise with ease on the highway, and feel a good and responsive pull in the hills. Based on what I'm reading, would it be as simple as just putting an 18T gear on the motor and leaving the rear at 34T...?
Thanks for the input.
I ride in the Santa Cruz Mountains, and up and down the California Coast. I also ride in the foothills around my area. I love the feel of a responsive throttle around the backroads, but I want to cruise with my friends at 80mph along the highway when we go on longer rides... Then there is the fact that to get to my friends I always have bout 10 extra freeway miles to and from home.
I don't take passengers on this bike. Not to mention I haven't even run this bike yet. This is also my first XS650. I've got a '79 special, it has 17/34 gearing. Anyone have suggestions of what I should do about the ratio? I want to cruise with ease on the highway, and feel a good and responsive pull in the hills. Based on what I'm reading, would it be as simple as just putting an 18T gear on the motor and leaving the rear at 34T...?
Thanks for the input.
Before replacing/changing any sprockets the first and obvious thing to do is to check your chain and sprockets for wear.
Any wear then it is best to replace the lot, sprockets and chain.
If you haven't run the bike then you will never really know how different one set is in relation to another. Relying on others for input is varied and depends on preference, riding style, and the area they ride.
I used to do a lot of 2 hour trips with 17/34 on the highway/main road, (not expressway), a lot of flat and some rolling hills and a couple of twistys and i would cruise at 120kph, 75mph and thought it was comfortable enough. 17/32 and 17/34, (standard size sprockets), will take the same chain 104 links. There is a 33T rear sprocket as well.
The only way to really tell for your self is to spend the money on the different sized sprockets and a chain.
if i am reading it right nj1639 says he runs a standard 104 link chain with an 18/32 combo effectively a 17/30, so you may also find an 18/33 suits.
If you buy 32T, 33T rear and a 17T and 18T front then with the combinations above you would find your nitch. And a 104 link chain of course
Any wear then it is best to replace the lot, sprockets and chain.
If you haven't run the bike then you will never really know how different one set is in relation to another. Relying on others for input is varied and depends on preference, riding style, and the area they ride.
I used to do a lot of 2 hour trips with 17/34 on the highway/main road, (not expressway), a lot of flat and some rolling hills and a couple of twistys and i would cruise at 120kph, 75mph and thought it was comfortable enough. 17/32 and 17/34, (standard size sprockets), will take the same chain 104 links. There is a 33T rear sprocket as well.
The only way to really tell for your self is to spend the money on the different sized sprockets and a chain.
if i am reading it right nj1639 says he runs a standard 104 link chain with an 18/32 combo effectively a 17/30, so you may also find an 18/33 suits.
If you buy 32T, 33T rear and a 17T and 18T front then with the combinations above you would find your nitch. And a 104 link chain of course
That sounds like a good idea. I think I'll buy an 18 front and a 32 rear. That will give me a place to start experimenting. Then if needed I can look for a 33.
The sprockets on the bike are in great shape, and there is no chain. That goes on the list.. I still haven't researched, but I'm sure there is a thread on here about all the best chains on the market. I'll have to look into them soon.
The sprockets on the bike are in great shape, and there is no chain. That goes on the list.. I still haven't researched, but I'm sure there is a thread on here about all the best chains on the market. I'll have to look into them soon.
There are 520 and 530 sprockets and chains. Will have to figure out what your existing ones are and match with the new. 520 is narrower than 530
80brat
XS650 Addict
any advice on changing to 520 chain ,
Today, there is no reason to use a 530 chain on a 45-60 hp bike. Older aircooled Ducati 900s use 520 chain, and they have 75-80 rwhp stock, and up to 100 rwhp when seriously modified. Going from 530 to 520 saves weight, and possibly cost also.
The secondary gearing is a tricky issue with our XS650's, limiting the selection of alternative rear hubs/wheels, causing problems with chain rub when using longer shocks to improve handling, 18 t fronts causing shifter axle issues, and so on.
I am a bit amazed that there is so little focus on the rolling diameter of the rear wheel, as a larger rear wheel would both raise the gearing and alter the steering geometry towards less rake. A 4.00-19 has around 3.85% larger diameter and rolling circumference than a 4.00-18. Low profile tyres may have larger or smaller circumference, depending on width and ratio.
Today, I am so pissed off at myself for having my new disc brake rear wheel built with a 2.50-18 rim. I definitely should have gone for a 2.50-19 instead. I guess you all call that 20/20 hindsight.......
The secondary gearing is a tricky issue with our XS650's, limiting the selection of alternative rear hubs/wheels, causing problems with chain rub when using longer shocks to improve handling, 18 t fronts causing shifter axle issues, and so on.
I am a bit amazed that there is so little focus on the rolling diameter of the rear wheel, as a larger rear wheel would both raise the gearing and alter the steering geometry towards less rake. A 4.00-19 has around 3.85% larger diameter and rolling circumference than a 4.00-18. Low profile tyres may have larger or smaller circumference, depending on width and ratio.
Today, I am so pissed off at myself for having my new disc brake rear wheel built with a 2.50-18 rim. I definitely should have gone for a 2.50-19 instead. I guess you all call that 20/20 hindsight.......
After shift, while working on my cylinder head, I thought about this some more. What is the general consensus regarding gearing with rephrased engines?
I am particularly interested in experience with altered gearing from bikes with 277 rephase, 750 kit, and hotter cams. Most engine tuning moves the power curve up in the rpm band, and for normal street riding, raising the gearing then seems counterproductive, more power at rpms that you never use. Any other thoughts on this?
I am particularly interested in experience with altered gearing from bikes with 277 rephase, 750 kit, and hotter cams. Most engine tuning moves the power curve up in the rpm band, and for normal street riding, raising the gearing then seems counterproductive, more power at rpms that you never use. Any other thoughts on this?
A larger specialty rear rim and specially made spokes to suit is a lot of extra money that could be spent on a 5th gear overdrive or even a set of racing primaries. Most go for an 18" front wheel for lowering the rake. Readily available
your last post kind of contradicts your first as it seemed you had the run down on gearing so i don't know how to answer
your last post kind of contradicts your first as it seemed you had the run down on gearing so i don't know how to answer
650Skull,
The smallest sprocket that fits my new rear wheel is 36t, so a 19" wheel would give me more scope for higher gearing. With 18 front and 36 rear, the highest possible gearing is the same as 17/34. Regarding cost, a high primary gear set costs more or less the same as my new rear wheel built on a Talon MX hub, with a 250 mm ISR disc and alloy 520 sprocket. This wheel also saves a lot of unsprung and rotating weight as well, and would have cost more or less the same with a 19" rim as a 18" rim. Most of the cost is in the hub and labor anyway.
The smallest sprocket that fits my new rear wheel is 36t, so a 19" wheel would give me more scope for higher gearing. With 18 front and 36 rear, the highest possible gearing is the same as 17/34. Regarding cost, a high primary gear set costs more or less the same as my new rear wheel built on a Talon MX hub, with a 250 mm ISR disc and alloy 520 sprocket. This wheel also saves a lot of unsprung and rotating weight as well, and would have cost more or less the same with a 19" rim as a 18" rim. Most of the cost is in the hub and labor anyway.
Here's another perspective, suitable for flogging by all interested members.
Horsepower requirements for top speed are generally a function of speed-cubed. All else being equal, especially aerodynamics, horsepower increase required to go from 100 mph to 200 mph is roughly 2 cubed, or 8 times more horsepower.
If you figure that a 650 upped to 750 gives a 16% boost in power, that should increase top speed 5%.
After I modified mine to 750, I put on a 18 tooth front, kept the rear at 34 tooth. A 6% change in gearing. Power had generally the same useability as it had with the 650cc/17T combo.
Of course, many changes occurred later, and it could use a 32 tooth rear now.
Horsepower requirements for top speed are generally a function of speed-cubed. All else being equal, especially aerodynamics, horsepower increase required to go from 100 mph to 200 mph is roughly 2 cubed, or 8 times more horsepower.
If you figure that a 650 upped to 750 gives a 16% boost in power, that should increase top speed 5%.
After I modified mine to 750, I put on a 18 tooth front, kept the rear at 34 tooth. A 6% change in gearing. Power had generally the same useability as it had with the 650cc/17T combo.
Of course, many changes occurred later, and it could use a 32 tooth rear now.
