Best way to measure for a new chain..

[Guest]

Ok so i am at a bit of an impass here with my cafe project...totall newb in this respect. 77 750B I have a 630 sprocket set, the front is the stock 15, the rear is a 52 tooth. I am switching from the standard swinger to an alum swinger, about 2 inches longer than stock, how do i measure for the new chain length? Anyone? Thanks!

TCK

[earlfor]

A #630 chain on a stock (15/42) GS750 is 96 links long. Probably the easiest way would be to wrap your old chain around the countershaft sprocket and onto the rear sprocket. Count the remaining sprocket teeth not covered by the old chain and and add that to 96 to get the total number of links you will need. (make sure your rear axle is near the center of the adjustment range before doing this)

You can also draw it out and measure your drawing or calculate it.
What is the distance between the center of the countershaft and the center of the rear axle when the axle is centered in the adjustment slot?

Earl

Ok so i am at a bit of an impass here with my cafe project...totall newb in this respect. 77 750B I have a 630 sprocket set, the front is the stock 15, the rear is a 52 tooth. I am switching from the standard swinger to an alum swinger, about 2 inches longer than stock, how do i measure for the new chain length? Anyone? Thanks!

TCK

[chef1366]

Your stock setup is a 15 teeth counter sprocket, 41 teeth rear sprocket and a 630/96 link chain.
I personally would lose that 52 teeth rear sprocket and go closer to stock or have a top speed of 55 mph. :shock:

With the setp you have now I'd add 11 links for the large rear sprockets and 2 links for the extra two inches. I'd get this and remove the extra links not needed.

[TheCafeKid]

Your stock setup is a 15 teeth counter sprocket, 41 teeth rear sprocket and a 630/96 link chain.
I personally would lose that 52 teeth rear sprocket and go closer to stock or have a top speed of 55 mph. :shock:

With the setp you have now I'd add 11 links for the large rear sprockets and 2 links for the extra two inches. I'd get this and remove the extra links not needed.

Yeah ive been lookin for a more mild rear sprocket...need to find a middle ground. That 52 tooth rips ass off the line, but like you said, it winds out FAST. i have a 41 tooth i may go with for the time being, unless i can find like a 45 tooth or something inbetwixt.

[Mark M]

I don't have it handy at the moment, but go to a couple of chain manufacturer's web sites and they will have the formula for calculating chain length for any center distance/sprocket size/chain pitch you can name. Way easier than hacking in the garage and guaranteed to to get it right the first time...

Maybe even google chain length calulator or similar.

Edit: I just googled it and a bunch come up...

http://www.machinehead-software.co.uk/bike/chain_length/chain_length_calculator.html

Mark

[TheCafeKid]

Thanks Mark! That should come in handy

[chef1366]

I am a hack...........:-D

[TheCafeKid]

Whatever Bill! You know and i dont! Well..didnt, now i do That chain calculator is for a bike chain tho..i wonder if it will make a difference? Arent the chain links themselves longer on motorcycle? Or maybe they just look that way.

[mriddle]

A #630 chain on a stock (15/42) GS750 is 96 links long. Probably the easiest way would be to wrap your old chain around the countershaft sprocket and onto the rear sprocket. Count the remaining sprocket teeth not covered by the old chain and and add that to 96 to get the total number of links you will need. (make sure your rear axle is near the center of the adjustment range before doing this)

You can also draw it out and measure your drawing or calculate it.
What is the distance between the center of the countershaft and the center of the rear axle when the axle is centered in the adjustment slot?

Earl

Do what Earl said .. can't go wrong.


Mike

[Mark M]

Whatever Bill! You know and i dont! Well..didnt, now i do That chain calculator is for a bike chain tho..i wonder if it will make a difference? Arent the chain links themselves longer on motorcycle? Or maybe they just look that way.

The formula holds for any pitch/center distance/sprocket size combo you can have. You do need to know the basic dimensions of everything to make it work.

In the chain number, the first digit is the pitch distance in 1/8's of an inch. So 6XX chain has a 3/4" pitch (6x1/8) and 5XX chain has a 5/8" pitch distance.

So you need to measure the center distance between your front sprocket and the rear sprocket, with the axle centered in the adjusters. Remember to measure with the front sprocket, swing arm pivot and axle all in line (usually with the suspension more than halfway compressed), that is the longest distance possible for the chain run.

Then work out the number of links you need with the formula. If you end up with a half number (I think it is) then you need to go up to the next full number of links.

Mark