Looking to change the sprocket on my GS 450 for more acceleration. Bike is a 6spd and 99% of the time I'm in town or on a 50mph highway.. I have 0 idea what to change it too. First bike...yadda yadda.
Thanks.
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Jan. 22, 2012 3:02 p.m. AutoXR HalfDork
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Jan. 22, 2012 3:33 p.m. 44Dwarf Dork
go down 1 tooth on the front or up three on rear. What year GS?
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Jan. 22, 2012 4:02 p.m. Taiden SuperDork
go for something about the size of a pizza pan
The thing about sprocket changes is this...
As 44dwarf has stated, generally speaking 1 tooth down in the front is about the same as 3 teeth up in the back. There are pros and cons to each method.
1 down in the front:
Pros: generally can use the same chain length as stock
Cons: higher chain wear at the front sprocket, generally harder to change3 up in the back:
Pros: reduced chain wear over stock, generally easier to change
Cons: may need a longer chain -
Jan. 22, 2012 4:21 p.m. AutoXR HalfDork
it's an 1980... Thanks for the advice - Will order new chain too!
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Jan. 22, 2012 4:43 p.m. Taiden SuperDork
Alternatively, tell us what RPM you would like to cruise at at 50mph, and what RPM you currently cruise at, as well as your front and rear sprocket size and we can probably come up with an exact number to start with.
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Jan. 22, 2012 5:00 p.m. 44Dwarf Dork
Allways change all 3 at same time to avoid wearing the new parts out faster. I'll look on the shelf and see what i have for made in the usa NOS steel sprockets. Still have a hunred or so. but don't have decode book so only know the 1 or 2 model listed on the boxes so can't cross ref.
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Jan. 22, 2012 5:14 p.m. Zomby woof SuperDork
The JT sprocket site can be used for cross referencing. It also has a pic of each application, with dimensions.
I would do the front, and if everything is in decent shape, nothing wrong with just changing the sprocket.
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Jan. 22, 2012 7:00 p.m. Curmudgeon SuperDork
If you supply the stock gearing and RPM you want, don't forget that tire outside diameter is important too. If you go with a taller rear tire it's like going smaller on the rear sprocket (the taller tire will turn fewer RPM per mile).
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Jan. 22, 2012 7:11 p.m. Taiden SuperDork
PS: I did not have sexual relations with your wheels. (But would certainly like to.)
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Jan. 22, 2012 8:35 p.m. nicksta43 Reader
Taiden that is weird,I heard a news story on the radio about people that want to have sexual relations with vehicles. It's more common than one would think.
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Jan. 23, 2012 12:52 a.m. Appleseed SuperDork
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Jan. 23, 2012 9:34 p.m. AutoXR HalfDork
why is the principal of sprockets so different then logic?
Take your bicycle to example ..the smaller the rear sprocket the quicker you accelerate, but also the quicker you run out of breath and need to shift..
So why do I go larger in the rear and not smaller when it comes to increased acceleration? I see the stunt guys and their rear sprockets are massive...
I have no doubt u guys are right ..just need to understand it.
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Jan. 23, 2012 9:43 p.m. Taiden SuperDork
Your sprockets make up your final drive ratio
Larger rear sprocket means more accel less top speed.
Opposite for the frontI think your bicycle example is backwards in your head.
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Jan. 24, 2012 7:42 a.m. 44Dwarf Dork
you've got it backwards. Smaller rear gets you closer to 1:1 ratio if you want to acell quicker you want more of a ratio. if you want speed you want closer to 1:1
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Jan. 24, 2012 7:54 a.m. Taiden SuperDork
Think of It like this. The rear sprocket is a torque arm. With a larger sprocket you'll have a longer torque arm. It's like a breaker bar vs a stubby wrench
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Jan. 24, 2012 8:17 a.m. AutoXR HalfDork
makes sense now - thanks guys
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Jan. 26, 2012 2:43 p.m. TuffWork Reader
I used to ride BMX when I was younger. It was kinda opposite in my head too. My bike that I still ride with my son from time to time has a 9 tooth in the back. However, you have to realize that a motor makes power using revolutions. Your muscles do not. The faster you move your legs the harder you have to work. The faster a motor is running it has an easier time pushing the weight. That's why peak horsepower as at the highest usable RPM (or thereabouts) for an engine. The goal of changing the sprocket is to be at a higher RPM in all gears and thus be closer to that peak horsepower. However, the sacrifices are gas mileage and top speed. That's why you see stunters with huge rear gears. Those bikes could easily go 170+ but they are trying to use all that power to just go 20 in a parking lot and do some cool circle wheelies.
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Jan. 26, 2012 4:45 p.m. 44Dwarf Dork
My old Sunstar book show stock would be 45 rear 16 front it also shows front from 13 to 17 the only front i have is a 16 (got two of them) I don't have a rear at all.
