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
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;)
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
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
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
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
RK Standard Chain
Quotequote: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.
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
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
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
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
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
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
They last nearly forever, especially in muddy conditions.
Brian
I've had several chains that seemed to be in ok shape until I check them for stretch and to me on my big bore bikes that seems to more important. I guess I am not sure how a o ring chain could slow down chain stretch, any ideas?
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
Chains don't really "stretch." For a chain to do that, the side plates would have to get longer, and this would change the pitch, and then the chain wouldn't fit the sprockets anymore. What does happen is the pins and rollers wear, and when that happens, the collective additional clearance of all the pins in all of the rollers adds up, and is what makes the chain get longer, or loose and sags as it sits on the sprockets. Compare a new chain to the pins and rollers of a worn out chain and you'll see what I mean. The big enemy of a chain is dust and dirt, and the o-rings and seals on the modern chains keeps the factory applied lubricant in the rollers, and the dust and dirt out. I don't ride anywhere near as much as some of you guys do, so I know I'll never wear out even a cheap, plain link chain, but I almost never hear of a chain breaking these days like you used to see it back in the day. This is one area where metallurgy and design has greatly improved and changes the old saying to, "They don't make them like they used to, they make them better!"
Type at you later,
Dan McEntee
Right, chains dont stretch, the pins and rollers wear. On an o-ring chain everything but the bushing/roller that actually sits in the sprocket valley is sealed and basically never wears. They still need to be lubed because that one roller/bushing isnt sealed.
Brian
For my vintage bikes that don't get ridden that much, I just use a good quality standard chain and keep it in good shape. On my modern bikes that I use more often, definatly a good o ring. Don't care about the newer x ring types as I have found they drag are stiff enough that it seems that I have the brakes on when moving it around.
'12 Husaberg TE300
74 Yamaha TY 250
84 Yam IT200
75 Jackpiner w/ 250 eng.
82 KTM GS250II (import)
82 KTM 495 (2)
98 KTM 300mxc
04 KTM 125 SX
00 KTM Duke 2/rd. racer
06 KTM 950 Adv.
08 Suzuki DR70Z
For my vintage bikes that don't get ridden that much, I just use a good quality standard chain and keep it in good shape. On my modern bikes that I use more often, definatly a good o ring. Don't care about the newer x ring types as I have found they drag are stiff enough that it seems that I have the brakes on when moving it around.
'12 Husaberg TE300
74 Yamaha TY 250
84 Yam IT200
75 Jackpiner w/ 250 eng.
82 KTM GS250II (import)
82 KTM 495 (2)
98 KTM 300mxc
04 KTM 125 SX
00 KTM Duke 2/rd. racer
06 KTM 950 Adv.
08 Suzuki DR70Z