125m/70 conversion chain issue

[DDQ]

I just put a 125m motor in an 85 70 chassis. I did a lot of research on here before doing it and everything I read said I could run a 428 chain with the 420 rear sprocket. That is absolutely not the case. I bought a new chain from parts unlimitted and have tried it with three different atc70 rear sprockets and it will not work.

Can anyone tell me if I can get a 428 rear sprocket that fits the atc70?


http://i130.photobucket.com/albums/p275/nissan11/Mobile%20uploads%203/20170226_143249_zpscyrszhs2.jpg (http://s130.photobucket.com/user/nissan11/media/Mobile%20uploads%203/20170226_143249_zpscyrszhs2.jpg.html)

[fabiodriven]

I'd like to see where you got that suggestion. That makes absolutely no sense.

[big specht]

Who ever said that had never tried it that's for sure. As for a sprocket I'm not sure you could make a hub that uses a 110 sprocket that way you would be back to 428 tooth

[DDQ]

I emailed dratv and he sells a 428 42t rear sprocket that will fit the 70 so I ordered one.

[shortline10]

The only difference between a 420 and a 428 is the width of the chain , a 428 is just a little wider , the spacing is the same . Your chain must be the wrong size .

[BOB MARLIN]

Change the front sprocket to a 420 ?.

[briano]

Looks like you have a 430 chain. I've done several 110 swaps into a 70 and just use the 110 chain which is a 428. As shortline said, the only difference is the width.

[fabiodriven]

The only difference between a 420 and a 428 is the width of the chain , a 428 is just a little wider , the spacing is the same . Your chain must be the wrong size .

You learn something every day!

[DDQ]

This is what I ordered and what I received. It fits the front sprocket fine. Something in this thread doesn't add up ...


http://i130.photobucket.com/albums/p275/nissan11/Mobile%20uploads%203/Screenshot_20170226-171139_zpsavnbte2k.png (http://s130.photobucket.com/user/nissan11/media/Mobile%20uploads%203/Screenshot_20170226-171139_zpsavnbte2k.png.html)

[DDQ]

After some research, it turns out there is more difference between the chains than just width like some of the members here claim...


The roller diameters of the 420 and 428 chains are different. The 420 roller is .306 in or 7.77mm diameter and the 428 chain is .335 in or 8.51mm diameter so the rollers will not go down to the 420 sprocket.

[Dirtcrasher]

Well, I'll be a son of a trailprotrailprotrailprotrailprotrailpro.....

[fabiodriven]

The frig Shortline! Get your crap together!

[shortline10]

Right lol , I've done the 428 to 420 chain switch a few dozen times , never an issue . The specs are less than 1mm difference and your talking half of that on a round roller .

[DDQ]

Right lol , I've done the 428 to 420 chain switch a few dozen times , never an issue . The specs are less than 1mm difference and your talking half of that on a round roller .

The fact remains that the 428 and 420 chains have more of a difference than just pin width. I am glad you have been able to get by using a 428 chain with a 420 sprocket but it does not work for me and apparently it does not work for a lot of others.

I bought a 428 rear sprocket from dratv and it works great so I am back in business.