Yeah ..the oil when hot, also gets thinner ..
thinner oil means, that it gets past the rings more easily
thinner oil ..equals less wear protection
burns off.....cokes up your valves...
overheating of oil ruins its make-up
all rubber changes with many temperature extreams...cracks and fails ..valve seals fail.
An oil cooler will keep the engine at a more stable temperature ..help components and limit expanding and tightening up and galling .
BTW ...my posts seam to be taking sometimes over 24 hours to appear here
all the best...markj
________________________________
From: Dallas Denny <aegis@mindspring.com>
To: Honda-C70@yahoogroups.com
Sent: Monday, June 18, 2012 1:43 PM
Subject: [Honda-C70] RE: Oil Cooler
>Re: Oil Cooler?
>
>Posted by: "RICHARD RIPLEY" mailto:rlripley%40prodigy.net ip_95141_3
>
>Sun Jun 17, 2012 2:30 pm (PDT)
>
>
>Ok, why do you think you need an oil cooler?Â
>10s of millions of  C70s seem to be goin'  ok
>without one. My old Gunny said "If it ain't broke, don't fix it"
>What's your opinion, Mike?
>Richard
Air-cooled engines run hotter than water-cooled
engines, and so don't last as long. Motors run
hot when the bike is standing still or moving at
low speeds, especially on hot days. So yeah, it
is kinda broke, and why NOT fix it?
Lowering the oil temperature a bit would make for
longer engine life, so installation of a cooler
would ultimately be cost-efficient. (The new
Triumph Bonneville [I want one SO badly!] is
air-cooled, but with a stock oil-cooler, quite nifty).
In 1969 I bought a new CL70 (same engine as C70,
according to Wiki) for I think $430 and drove it
long distances daily at high speed (about 50
mph). It was my only transportation. I changed
the oil every 300 miles. Every 10,000 miles or so
the engine would lose compression and I would
rebuild the top end. It cost only about $30 back
then, and took only about an hour, since I didn't
have to remove the engine from the frame, but at
43,000 miles the connecting rod broke and came
through the engine case. My Honda dealer told me
I could get a new engine for $200, but that was
all the money in the world back then, and that was the end of my CL70.
43k is fabulous longevity for a 70cc bike, but
I'll bet if I had had an oil cooler I would have
gone the entire 43k without a rebuild-- and who
knows, maybe the rod wouldn't have broken.
When Honda introduced the CX500 and Gold Wings
with water cooling, shaft drives, and tubeless
tires, motorcycles became a lot more reliable,
going to and even beyond 100k without any engine
work. I don't expect my CL70 to reach that level
of reliability, but with the oil 20 or 40 degrees
F cooler, I would feel I was treating my engine more kindly.
My first bike was a 1967 Honda C100, the 50cc
Cub, which was a fabulous bike-- so I understand
why everyone on this group loves their C70s.
Dallas
[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:
http://www.shlaes.com/Vehicles/Scooter.htm
http://www.velodrome.com/HondaC70/HondaC70.html
