I have a suggestion that makes this simple and much more accurate. If you have a Harbor Frieght store close by they have a micrometer that is longer than most swingarms for $10. Use it to measure from center to center of the axle and the swingarm bolt on the chain side. Then take it to the other and make them match. Under load of course which makes it somewhat of two person operation but easy and effective.
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From: Mike Gladu <firstname.lastname@example.org>
Sent: Tuesday, October 18, 2011 10:33 PM
Subject: Re: [Honda-C70] Drive chain tension problems
At 10:17 PM +0000 10/18/11, danhubin wrote:
>I have an 81 C70, and am having issues with the drive chain. I keep
>trying to tension the chain correctly, and on the center stand it
>seems great (about 1/2 inch play up and down with the tensioners
>pushed as far back as they can go). Once I start riding though it
>starts making a lot of noise and when I check the chain, sure enough
>it's laying on the bottom of the chain guard.
>I tried breaking a link out of the chain, but then even with the
>axle all the was forward it's too short to connect. I've noticed
>that the left tensioner, even adjusted to push the axle as far back
>as it will go, doesn't move the axle all the way to the back of the
>frame cut out.
>Has anyone else dealt with this issue?
Chain tension set with the wheel off the ground will be too tight
when bike weight and rider weight are added.
Add to that, when the chain is over tightened and you go for a ride -
it will can pull the axle forward, damaging the adjusters and
sprockets, and possibly stretch the chain.
Check chain tension again after an adjustment with the usual riders
full weight on the seat. If you need to make it looser - do so. Also,
make sure the adjuster nuts have been snugged up against the end of
the swingarm after the axle nut has been tightened. If left loose,
the axle can work its way forward on the chain side even after a
[Non-text portions of this message have been removed]
1970-73 C70 Honda Service Manual: http://tinyurl.com/6ebwtw
1970-73 C70 Troubleshooting Guide:
http://tinyurl.com/6ebwtw (scroll to sec.7.1 page 101.jpg)
1980-83 C70 Honda Service Manual: http://tinyurl.com/hu42c
1980-81 C70 Troubleshooting Guide:
http://tinyurl.com/hu42c (scroll to sec.18-1 page 170.jpg)
1982-83 C70 Troubleshooting Guide:
http://tinyurl.com/hu42c (scroll to sec. 20-28 page 205.jpg)
1980-81 C70 Maintenance Schedule: http://tinyurl.com/z4zn6
1982-83 C70 Maintenance Schedule: http://tinyurl.com/hw35c
More resources for C70 Passports and Cubs: