Ron -
Apparently it doesn't take much off n on stuff to lose the exhaust seal at the exhaust port. Took it apart - it looks like the half C split sections are worn just enough to allow lateral pipe movement.
Time for new split sections, a new gasket, one new stud etc then it will seal up more solid.
Later, the plan is to get a new Cub exhaust system with the wide end (no more splits).
The loose hanging of the pipe on-the-mounting-stud, then alternating tightening of the new fasteners seems to be a good idea. Its off to the dealer to get / order parts.
Rob
--- In Honda-C70@yahoogroups.com, "rdwnj" <rdwnj@...> wrote:
>
> Hello Rob,
>
> Can't say for sure, but on my C200 the idea is, I think, to hang the muffler on the frame mount(s) and position on the exhaust port bolts and in exhaust port, as best as you can first, holding by an exhaust port nut. The idea is to determine if some part, say the exhaust pipe is bent a little, or some such, which might prevent or make a good fit harder to attain.
>
> Good idea to get it in snug. Is the pipe flange hitting on the port walls, not allowing it to get to the gasket? Is the flange relatively smooth?
>
> And are the threads of the exhaust port studs and nuts clean? Sometimes from exhaust carbon, road dirt oil etc, the threads get so dirty, you can't feel what you are tightening, all you feel is the dirty threads, so you can't tell how hard to tighten. When you have things all clean, try the nuts on the bolts first, with no muffler to make sure everything is smooth. Sometimes one nut 'wants' to be on one bolt only.
>
> Now hang the muffler on the frame mount(s) with loose nut holding on so you can guide the flange in parallel to the port and gasket, then tighten the nuts alternately a little at a time, so as not to 'tilt' the flange in the port, perhaps wedging it in the port wall giving the appearance/feel of being 'in' when it isn't. The feel is in the hands. Maybe torque wrench to make sure not too tight? Don't know, never done it! Then snug up the frame mount (s) of the muffler. Good to clean those threads too.
>
> Others may comment on whether this is good advice, but kind of works for me :)
>
> Hope this helps, let us know what you find out.
>
> Ron in NJ
>
> --- In Honda-C70@yahoogroups.com, "zjwqtpng" <zjwqtpng@> wrote:
> >
> > Hey all - no doubt some owners have experienced this most frustrating problem; a leaking exhaust pipe at the head outlet.
> >
> > 1. Had my C70's exhaust pipe off several times due to a persistent exhaust leak. Removed old stack of exh. gaskets, cleaned the port ridge area then replaced with a new OEM gasket ring. Was quiet-er for a few days.
> >
> > 2. Recently I took my bike to a shop where the tech tightened the exhaust pipe after a rear tire change - no more exhaust leak! My C70 was whisper quiet!
> >
> > 3. Yesterday I installed a new center stand and re-aligned rear wheel & chain. Took exhaust pipe off, re-installed it using two C half-circle wedges; now it leaks again. Rats ...
> >
> > So what's the "quiet pipe" secret?
> > Does one have to replace the gasket ring every time the pipe comes off?
> > Does the pipe get pushed up moderately hard into the exhaust port and then re-tightened?
> >
> > Rob
> >
>
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:
http://www.shlaes.com/Vehicles/Scooter.htm
http://www.velodrome.com/HondaC70/HondaC70.html
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