Chain links

[Steve Minor]

I have a chain question....actually two. I'm working on a 1977 125 GS6 and need a chain.

(1) Is there a math formula to determine the number of links needed when I place an order? Like the overall length divided by some number = number of links required. Remember this is a long travel rear suspension.

(2) Once the number of links is determined, did this bike come with a 428 size chain? If not, what size is stock?

Thanks


Steve Minor
Wilmington, NC
1972 Six Day
1977 125 GS6
1977 400 GS6
1978 400 MC5

[Kip Kern]

May be a 520 as it is a later year, my 77 175 is a 520.  Contact Dennis Kirk and buy the longest they have in standard chain and then cut it to suit your machine!  Don't get a heavy duty or "O" ring as it will rub everything;)

[Steve Minor]

Thanks Kip...Any specific make you like? Does DID still make a decent chain?

Steve Minor
Wilmington, NC
1972 Six Day
1977 125 GS6
1977 400 GS6
1978 400 MC5

[slvrbrdfxr]

Steve and Kip,
I did a little research on 520 chains last summer when I was looking for a narrow width sealed chain to use on my Yamaha IT200. I needed to find something narrow enough so that it wouldn't rub the engine case at the c/s sprocket and suspect you will need something similar. I ended up buying an RK chain model GB520MXU which is a sealed chain that uses very thin flat rubber washers around each pin instead of the standard round o-rings. The overall width of the chain measured at the outsides of the pins was only slightly wider than a standard non o-ring chain and it worked great. They make this in a 120 link length which should be more than long enough to fit your 125GS. I bought mine at my local Cycle Gear store and it was a bit pricey but in my opinion was worth the extra money over the long haul. You can usually find them online for approx $80. Hope this helps.
Dave McCullough

[Steve Minor]

Thanks for the advice...As usual, POG members come through.

Steve Minor
Wilmington, NC
1972 Six Day
1977 125 GS6
1977 400 GS6
1978 400 MC5

[firstturn]

Speaking of Chains and sprockets here is some neat information that I think Bob Wordlow put up some years ago.  I know I had some of the same information back in the old days of Honda Technician training.

http://www.gizmology.net/sprockets.htm

Ron Carbaugh

[Kip Kern]

RK Standard Chain

[Darvin Jahnke]

quote:Originally posted by kip kern

RK Standard Chain

I agree. Think about how much h.p. is required to wrap an o ring or sealed chain as compared to a regular chain. In land speed racing we use plain old chain for this reason. Just replace it at regular intervals or anytime it shows stretch or wear.

[SouthRider]

Would never use o-ring chain on a 125 due to power loss.

_____________________________________________________________________________________

"We the willing, led by the unknowing, are doing the impossible, for the ungrateful. We have done so much, for so long, with so little, that we are now qualified to do almost anything, with nothing."

1972 Penton Berkshire 100
1983 Husqvarna 250 XC
2011 Jayco 31.5 RLDS
2009 Chevy 2500 HD Duramax

[BrianTaylor]

Here is the actual formulae

L=(N1+N2) /2 +2C+(N2-N1) squared /6.28 / C

L= Chain length in pitches
N1 teeth of small spkt
N2 teeth of large spkt
C= center distance in Pitches
any fraction is counted as 1 pitch

Brian Taylor

[brian kirby]

Modern o-ring chains have very little drag. If you are racing for money, or at a land speed event maybe a standard is the way to go, but for the pretend racing we do with these old bikes, an o-ring is the way to go, I have one on my 100 and it has not hurt HP at all.

DID makes a very narrow "T" ring chain with very low drag called the VT2.

//www.didchain.com/motoChains.html

Brian

[tomale]

My reasons for using a standard chain has little to do with HP, so why should I use a t ring chain? I don't mean to be contrary , I am just curios.

Thom Green,Still crazy after all these years!
76' 250 MC5 (orginal owner)
74' 1/2 440 maico
70' 400 maico (project)
72' cr125 Husky (project)
93' RMx 250 suzuki

[brian kirby]

The T ring chain is barely wider than a standard chain and any sealed chain will last 10x longer than a regular chain. The o-ring chain on my 100 has been on there since '08 and after the first couple rides, I have not even had to adjust it in all that time.

Brian

[tomale]

My reasons for using a standard chain has little to do with HP, so why should I use a t ring chain? I don't mean to be contrary , I am just curios.

Thom Green,Still crazy after all these years!
76' 250 MC5 (orginal owner)
74' 1/2 440 maico
70' 400 maico (project)
72' cr125 Husky (project)
93' RMx 250 suzuki

[brian kirby]

They last nearly forever, especially in muddy conditions.

Brian