I have tested oil temps in a few scooters I have because I use a oil dipstick temp gauge. I know dratv sells one for the c70 engine also but have not yet got one
But here are some results
125cc forced air cooled scooter 210F
Same scooter with 155cc engine 220F
Same scooter with 155cc engine and oil cooler 180-185F
50cc water cooled scooter around 90C but since thats water cooled not sure if that applies
125cc lifan motorcycle engine air cooled 250F (very hot)
140cc lifan type motorcycle engine air cooled 250F (very hot)
Same 140cc engine with oil cooler 200-205F ( I now use cheap oil )
So we can see oil coolers really do bring down the temps
Now im using motul with ester I believe 5100 type oil for my c70
if you look at there chart online it protects the best at 250F
now that temp is still over the safe limit of motul but it outperforms normal motor oil at those temps
Since I cant say 100% yet what my c70 runs at im guessing around 250F temps
One day I will check but I figure using $10 quart motul is better protection then cheap motor oil because I have no cooler and I drive it hard and fast
Since I dont live in 3rd world conditions I will take advantage of the better oils available whether or not its really necessary
--- In Honda-C70@yahoogroups.com, mark jones <aboard_epsilon@...> wrote:
>
> Yeah ..the oil when hot, also gets thinner ..
> Â
> thinner oil means, that it gets past the rings more easily
> Â
> thinner oil ..equals less wear protection
> Â
> burns off.....cokes up your valves...
> Â
> overheating of oil ruins its make-up
> Â
> all rubber changes with many temperature extreams...cracks and fails ..valve seals fail.
> Â
> An oil cooler will keep the engine at a more stable temperature ..help components and limit expanding and tightening up and galling .
> Â
> Â BTW ...my posts seam to be taking sometimes over 24 hours to appear here
> all the best...markj
> Â
> Â
> Â
>
>
> ________________________________
> From: Dallas Denny <aegis@...>
> To: Honda-C70@yahoogroups.com
> Sent: Monday, June 18, 2012 1:43 PM
> Subject: [Honda-C70] RE: Oil Cooler
>
>
>
> Â
>
>
> >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
