Honda C50 top speed

**xww10** · 9th April 2008, 09:12

I've been told that my Honda C50 is too slow. It does 55-58kph in 3rd gear (it has 3 gears). Does this sound right or is my engine stuffed?

**F5 Dave** · 9th April 2008, 17:47

I seem to remember speed testing a mates as a kid, think we got up to high 40s, maybe 50mph. So 80k should be achievable. Google it, must be heaps of info on the web,

Hold on, good ol wikepedia
http://en.wikipedia.org/wiki/Honda_Super_Cub

**Motu** · 9th April 2008, 17:56

My '81 C50 would do 80kph - juuuuust able to go on the motorway.

**xww10** · 9th April 2008, 18:38

Damn... what's wrong with mine then? where do I start?

**xwhatsit** · 9th April 2008, 23:35

I dunno, it's pretty old, innit? See if you can nick some bastards compression gauge. Teh intarnets tells me that you need at least 100psi to consider your engine healthy. Not sure if that applies to tiny wee 50cc pots, though.

**marty** · 10th April 2008, 07:50

I had a C50 back in the 80's that ran on avgas, and would do 80km/h.

It would only do that for 5 minutes though, then it would thermally sieze....10 minutes later when it cooled i could kick it over again.

Another guy at work blew a hole in his piston using avgas, so he turned one down on the lathe. Out of an Oak branch. It ran for a year with a wooden pistion and no rings.

**kiwifruit** · 10th April 2008, 08:01

Originally Posted by marty

Another guy at work blew a hole in his piston using avgas, so he turned one down on the lathe. Out of an Oak branch. It ran for a year with a wooden pistion and no rings.

Classic!!

**xww10** · 10th April 2008, 09:52

Is there some kind of restrictor somewhere i.e. in the exhaust?

**F5 Dave** · 10th April 2008, 11:28

No, the restrictor is in the specification. But the usual suspects are compression & timing. Check both & maybe airfilter isn't clogged.

**Bonez** · 10th April 2008, 16:11

Originally Posted by xerxesdaphat

I dunno, it's pretty old, innit? See if you can nick some bastards compression gauge. Teh intarnets tells me that you need at least 100psi to consider your engine healthy. Not sure if that applies to tiny wee 50cc pots, though.

All depends on the compression ratio. Even old C50s that are looked after should be able to get up to 70kph on a good day. Had my '72 up to 50mph on a still cool summers morning not long after I got it. Could have gone a bit faster but didn't want to risk it.

Worshop manual is available here, not free but hey:

http://www.tradebit.com/tagworld.php/workshop+manual

**xww10** · 10th April 2008, 18:11

I'll check compression and get back ASAP. Mine maxes out at 58kph on a flat. Engine sounds like its going to explode at that speed. Just did the tappets and its got a new plug.

**Motu** · 10th April 2008, 22:47

They spin to 9,000rpm,and I don't think you can blow one up.Get an SS50 top end with the hot cam and big ports,valves and carb and it'll make more HP than a 70cc.Or put a 70cc top end on.Or go for a clone.As I mentioned in the other C50 thread - oil level is important,too much and the crankshaft drags in the oil cutting hp.....this is really noticeable on the C50 because you haven't got any hp to loose.I'm sure if you went to a 0/20 synthetic you'd pick up some power too.

**xww10** · 11th April 2008, 07:51

Thanks Motu. what sort of oil do u recommend? The previous owner left some 10w40 atv oil so i'm just using that. I've been eyeing a 110cc clone engine on trademe. Now that would be something...

**Motu** · 11th April 2008, 18:46

I don't think the oil matters - but it's just that I noticed they are suseptable to oil drag,something that would never be noticed on other bikes.I couldn't get up my drive in the mornings after an oil change.....but a few weeks later it was no trouble.It's a very small thing,and on a small bike it's the little things that matter.Just play around,it's half the fun.